I talked with the Director of R&D at Mazda about dynoing the RX-8 on a chassis dyno. He said don't do it until well after 1000-2000 miles have been put on the car, and the engine brakes in. . . "Said" is even the wrong word, he "implored" me to brake it in first...

So, get out and brake those engines in, and then retest them at, say, 5000 miles.

-----

8/22/2003

Official HP Revision: See http://rotarynews.com/view.php?id=206

thanks for the info, how about the ecu does it make a chage over after x number of miles ?

Thank you!


Any specifics on why the break-in is so critical?

Originally posted by rotarynews.com
I talked with Kelvin Hirashi, Director of R&D at Mazda about dynoing the RX-8 on a chassis dyno. He said don't do it until well after 1000-2000 miles have been put on the car, and the engine brakes in. . . "Said" is even the wrong word, he "implored" me to brake it in first...

So, get out and brake those engines in, and then retest them at, say, 5000 miles.

On the latest dyno reported on the forums the car had 2215 miles on it but still came up with only ~180 rwhp.

Any info on the suspected XX,XXX miles ECU fuel mapping switch?

There may be a number of things that could account for the lower numbers.. These are some thoughts:

1. Did you hookup a wide band O2 sensor, and mionitor the A/F. It may be running rich to protect the engine durring break in

2. The tests have all been under warm/hot conditions. The "correction" might not be enough for a rotary.

3. The engines still may be tight and need to be broken in.


A little waiting and I should have more answers.

yes please stay in contact w/ Mazda to find out the real answer to the dyno question, and quell all these speculations/rumors

rumors are BAD mmmmmkay? :D

good stuff, thanks Dan. :)

Will do! Thanks!

Vince

This is definitely a step in the right direction.

Will await more detailed info from Mazda on this. Would really like to believe that their credibility is not at issue here...

Thank you rotarynews.com

Kind regards,
LK

Thank you, rotarynews!

I'm eagerly awaiting a definitive answer to this issue. Getting confirmation that this power loss is not a sign of a defective engine is pretty important to my decision whether or not to pursue getting the RX-8. I won't do anything until I find out the answer.

i just want to say you are really hardcore cuz instead of waiting for the dyno chart from Import Racer magazine, you guys take your own car out....

awesome

Guys:
Dan and I have been working on this since it first broke. We plan on getting the RN.com RX-8 on the dyno after a decent break in period. We want to give Mazda the benefit of the doubt here. Both of us drove PRODUCTION cars that actually felt faster and stronger then the PRE-PRODUCTION models, so we know the cars have the power.

In the background, I've been talking to folks and trying to get some valid information for you all. We know of a few other 8s that have been dynoed with similar results. Please look for an upcoming story on this at RotaryNews.Com very soon!!

Guys remember that Mazda can and probably will NOT comment on this publicly, until they have all of the facts and can present them in a way that will be satisfactory to the consumer and their own marketing and legal departments. I'm sure that any OFFICIAL Mazda comment, be it positive or negative on this issue, will be well thought out and forthcoming. Unfortunately, this is one of the issues we face living in such a litigious society. This of course is NOT to imply that anything is wrong with the RX-8.

The statements that were made to Dan by Kelvin, were directly in regards to the RN.com RX-8 being dynoed, but should be followed as a recommendation to all thinking about it. Nothing official should be read into Kelvin's statements to RN.com on this issue.

We'll get to the buttom of this and we thank all of the folks who to date have contributed their dyno sheets and commentary.

-Bern

thanks dan and bern for getting into this quickly. glad to have you guys on the job:)

Regarding Dyno, found this little interest read on page 64 of SCC, Sept '03 issue. They were trying to Dyno their test cars: EVO, Audi S4, M3, and 911 4S.


THE DYNO: What Happened?
Dyno testing all-wheel-drive cars isn't easy. Hell, for that matter, dyno testing an M3 isn't easy. We ran into numerous problems during the course of this test, which prevented our usual dyno numbers from being included in the final results.
First, our attempts to dyno the 911 resulted in a very angry viscous coupling. The front and rear roller on HKS' all-wheel-drive Dynojet are different sizes and weights, which forced the Porsche's viscous coupling to work overtime trying to equalizing the speed difference between the front and rear wheels. We gave up when the 911 began to protest on the first pull.
The M3, despite being two-wheel-drive, is also remarkably dyno proof. Its eletro-trickery requires the front and rear wheels to be moving at the same speed or it won't allow maximum engine speed. The engine simmply stops revving at 6500 rpm on the dyno. The problem persisted even with the wheel speed sensors disabled.
With half the field unable to complete the dyno test, we scrapped the idea altogether.

That is interesting! Anyone heard of such a dyno that will properly test these cars, (hopefully) including the rx8?

Is there a loss in horsepower across the rpm range or only at peak (8,500 rpm)? If it is only at peak, sounds like ports still not opening.

Looking at the dyno plots, it certainly appears that the tertiary ports are opening just fine. I suppose it's possible that we're seeing the ECU cause the drop at port opening and that it's really not, but I doubt it. This appears different.

Dont believe everything you read, I have personally seen several E46 M3's dyno succesfully on a dynojet.

BTW, a broken in car might dyno 5-8hp more to the wheels than a car with 200-600 miles on the odo. but not a lot more. Ussually they dyno within 3hp.

Originally posted by bern
Guys:
...

Guys remember that Mazda can and probably will NOT comment on this publicly, until they have all of the facts and can present them in a way that will be satisfactory to the consumer and their own marketing and legal departments. I'm sure that any OFFICIAL Mazda comment, be it positive or negative on this issue, will be well thought out and forthcoming. Unfortunately, this is one of the issues we face living in such a litigious society. This of course is NOT to imply that anything is wrong with the RX-8.

...

-Bern

Bern, thanks for the update.

Yes they can comment very quickly if they know what is going on. It doesn't take a team of lawyers to tell the RX-8 customers, "When the car hits 4K miles the aggressive fuel maps kick in and the car will then be at full power."

IMO, they only need precisely written legalese when they have a problem or don't know what's going on.

-Mr. Wigggles

Originally posted by Urchin
Is there a loss in horsepower across the rpm range or only at peak (8,500 rpm)? If it is only at peak, sounds like ports still not opening.

On the Dyno plots, the power is reasonable up to 6000 rpm. It is from there on that the power isn't with-in the power specified by Mazda from their web-site or the torque (and thus power) curve from their press-kit.

-Mr. Wigggles

Yes they can comment very quickly if they know what is going on. It doesn't take a team of lawyers to tell the RX-8 customers, "When the car hits 4000K miles the aggressive fuel maps kick in and the car will then be at full power." That makes sense but all of us who've participated in the pre-order program no how incredibly bad communication from Mazda is. I have little doubt that the engineeers know what's going on it's just that either the lawyers or the marketeers or the public relations guys are once again off the mark on this.

I've made the same point several times as well:

If things are working as designed then we should be hearing from Mazda this week or next. All they have to say is "we currently believe the vehicle and engine are working as designed, more details will follow in a few weeks'. They don't have to say anything about possible ECU remapping (automatically or via dealership) or that the car might have 30% transmission losses instead of 17% etc. They don't have to tell the public (us) this either, just notify the dealers that if anyone asks about HP issues then this is the message to give them for now. My dealer has heard nothing about this yet.

The longer it takes Mazda to make any kind of announcement the more likely it is that there is a real problem and they are scrambling to research it and getting lawyers involved for wording.

btw....has anyone else noticed that they took the "Specifications" tab off the main USA RX-8 page (http://www.mazdausa.com/MusaWeb/rx8/rx8_main_flash.jsp) Are they trying to avoid something?

Originally posted by takahashi j
btw....has anyone else noticed that they took the "Specifications" tab off the main USA RX-8 page (http://www.mazdausa.com/MusaWeb/rx8/rx8_main_flash.jsp) Are they trying to avoid something?

Hmmm, odd but they still quote the expected power on the 'build' page:

247 hp 1.3-liter RENESIS 2-rotor, 6-intake-port, rotary engine

Originally posted by takahashi j
btw....has anyone else noticed that they took the "Specifications" tab off the main USA RX-8 page (http://www.mazdausa.com/MusaWeb/rx8/rx8_main_flash.jsp) Are they trying to avoid something?


You need to go through the Build and Buy and then download the specs as a PDF file. Why they did it that way? WHo knows.

In the performance section, it also still says "...with 247 horsepower @ 8500 rpm..."

My guess is that they are just updating the website, but I'm sure this will just feed the "controversy" frenzy.

Answers are coming soon... But I think in the other thread, Paul Yaw has hit upon the answer: AF Ratio being richened by the ECU.

Speculation: The ECU in the 8 is very high tech, but was not designed with chassis dynos on the mind... so the shock, load, and heat of the dyno run makes the ECU dump fuel into the engine to protect it, there by decreasing the horsepower and torque.

Here is my challenge to youse guys:

Dyno with

1. A wide band O2 Sensor

2. A Mazda Dignosis machine and monitor, in real time, the sensors (air temp, AF ratio, etc)

3. A cooler facility

4. The report back on the results before Mazda has a chance to :D


-----------------

takahashi: Mazda moved the specs onto the "normal" car section http://www.mazdausa.com/MusaWeb/displayPage.action?pageParameter=modelsSpecsSpecs&vehicleCode=RX8

Originally posted by rotarynews.com
Answers are coming soon... But I think in the other thread, Paul Yaw has hit upon the answer: AF Ratio being richened by the ECU.

Speculation: The ECU in the 8 is very high tech, but was not designed with chassis dynos on the mind... so the shock, load, and heat of the dyno run makes the ECU dump fuel into the engine to protect it, there by decreasing the horsepower and torque.


an ECU designed to PROTECT the engine? AMAZING!

http://www.mazdausa.com/MusaWeb/displayPage.action?pageParameter=modelsSpecsSpecs&vehicleCode=RX8

The specs seem easy enough to reach from the main page. It took me 3 clicks to get to that page.

For owners residing in Southern California, I am willing to provide a free dyno session to generate some more data on this topic.

We use a Dynapack chassis dyno, which is a bit different in that we remove the drive wheels and attach the dyno directly. This allows us to control load more precisely. The readings are usually somewhat higher than on a Dynojet (about 10-12 hp) because the load of the wheels isn't there.

The dyno also datalogs a MoTeC wideband O2 sensor, manifold pressure, etc. Additionally, we use a OBDII scantool to monitor intake and coolant temps to ensure consistency and real world relevancy.

We have dyno results from other cars in the same power range (in particular, many Honda S2000s which have similar driveline, power curve and torque delivery characteristics).

If a person (singular, can't be doing too many free service) would like to try his/her broken in car on the dyno, please feel free to contact me.

Shawn Church

Church Automotive Testing
20950 S. Normandie Ave.
Suite K
Torrance, CA 90502
310-787-7123
spchurch@earthlink.net

Originally posted by ChurchAutoTest
For owners residing in Southern California, I am willing to provide a free dyno session to generate some more data on this topic.

. . .

If a person (singular, can't be doing too many free service) would like to try his/her broken in car on the dyno, please feel free to contact me.
. . .
spchurch@earthlink.net

How's about the first person hit the 5000 miles mark? I only got 1200 miles. I would be interested and planning to take mine to a dyno anyway. Perhaps some discount would also work if more people interested? :D ;)

I'm willing to entertain other scenarios. :)

SC

p.s. - someone with about 2000 miles will be coming by in the next week or so. We'll have to see about higher mileage down the road.

Originally posted by MrWigggles


Bern, thanks for the update.

Yes they can comment very quickly if they know what is going on. It doesn't take a team of lawyers to tell the RX-8 customers, "When the car hits 4000K miles the aggressive fuel maps kick in and the car will then be at full power."

IMO, they only need precisely written legalese when they have a problem or don't know what's going on.

-Mr. Wigggles

I've should've stated and/or wrote it the following way:

".... their own marketing-PR and/or legal departments....."

I didn't mean to imply that the legal department was clearing anything.. on the other hand, marketing and PR might want to handle this situation delicately, even if it is just an ECU map thing... They may need to figure out how to desiminate the info to both consumers and dealers... and answer questions as to why this is happening, and why no one told anyone about it. Remember that dealers are Mazda customers too...

I was just saying that unfortunately, major corporations now-a-days just have to be very careful on any point... there is always one or two people who will have major issues with things, no matter what happens or is said..

Again I'm not implying that any of this is going on, it's just my own personal hunch.

-Bern

Around the middle of last week, I sent Mazda the following message:

"I'm a sportscar enthusiast who currently owns a 2000 SVT
Lightning and just came back from attending the MazdaRevitup stage 14 event in DC. While at the event, my wife and I got the chance to check out the all new RX-8 and I plan on purchasing one in the coming months.

However, I have a concern which I first saw addressed by Sports Compact Car in their May 2003 issue - the 6spd manual RX-8s not producing their advertised 247hp. Several new owners on the website www.rx8forum.com are also experiencing low dyno numbers ranging from 174-184hp for their 6spd manual cars.

Now I'm not looking for the standard, blow-me-off "It makes
247hp at the flywheel" type of answer, as I know enough about cars to not accept a 25.6% drivetrain loss in a car built after 1980 w/ a 6spd shifter and a carbon fiber driveshaft. You could earn the respect of a potential valued customer with your response."


Mazda e-mailed me back with the following response this evening:


"Thank you for contacting Mazda North American Operations. I appreciate the opportunity to respond to you.

In regards to your question, Mazda is aware of the reports showing that the 2004 RX-8 has lower horsepower than advertised. Currently Mazda is looking into these reports. Until further research is done on this matter, Mazda is not able to comment on these reports. Please know your comments have been documented and are continuously reviewed by the Product Planning Department in an effort to provide only the most
exciting vehicles.

I am pleased to hear of your enthusiasm for the 2004 RX-8! We would love to have you and your wife as part of the Mazda family!

Again, thank you for contacting Mazda. It has been my pleasure to assist you. If for any reason this response has not completely
satisfied you, please feel free to reply to this message. You may also contact our Customer Assistance Center toll-free at 1-800-222-5500.

Sincerely,

Heather Drake
Specialist, Customer Assistance E-Business"


Well Mazda is aware of the problem at this time and we should all be hearing something from them officially in the coming months. It wouldn't surprise me if it was a "quick fix" like an update to the ECU (a couple members mentioned that the cars are shipped from Japan without being CA emissions compliant, but at the port technicians put in a US spec ECU).

Shawn-

Please make sure to post the results of your test on the RX-8 you have coming in, either here or on TOV (vtec.net for all you Honda haters).

For those of you who don't know, Shawn Church is about one of the smartest guys you'll ever meet---on the net or in person. He knows more about automotive engineering than most people. I know he'll make sure that the RX-8 is tested fairly and that all variables are measured and taken into consideration.

You don't suppose that the engines are really all 4 port or something instead of 6 port do you?

The new "Wired" has a nice two page spread on the 8 and it still says 247hp. I don't think thye would keep advertising it if it wasn't true particluarly given the Miata fiasco.:cool:

Originally posted by RodsterinFL
You don't suppose that the engines are really all 4 port or something instead of 6 port do you? Were are very sure that this is not the case. We see the 5th/6th ports kick in on the plot, and we would not see the overrich situation.
Originally posted by TybeeRX-8
The new "Wired" has a nice two page spread on the 8 and it still says 247hp. Ads are sent into the magazines a LONG time in advance. Chances are, the magazine had that ad before the first RX8s hit these shores.

---jps

Will do. If time allows, we'll do a quick trip around the block and note normal operating temperatures (intake and coolant) and try and duplicate those as closely as possible on the dyno. I'll also provide comparison plots with other RWD cars of similar rated power levels (Honda S2000, Nissan 350Z, etc.)

And thanks for the kind words :)

SC

Originally posted by rxtreme
Shawn-

Please make sure to post the results of your test on the RX-8 you have coming in, either here or on TOV (vtec.net for all you Honda haters).

does anyone know the model, brand, and type of dynamometer used in the results that show lack of power? has anyone looked into any dyno graphs made by Japanese owners/tuners? remember they are rated in PS - which is 1.25 hp. If someone can find a Japanese dyno graph, we can narrow it down to just a US Spec problem, most likely the ecu which is different in comparison to the JDM Spec.

Originally posted by ChurchAutoTest
p.s. - someone with about 2000 miles will be coming by in the next week or so. We'll have to see about higher mileage down the road.

We've already seen a 2000 mile car dyno'd and it wasn't much different than the 800 mile car - and it's been suggested that the engine isn't broken in yet as far as making max power at 2000 miles. Unless you are going to dyno the exact same car at around 5000 miles (for which a dyno run at 2K miles would be an excellent baseline and comparison), then another dyno run on a 2K miles car might be a waste of time... we (the RX-8 community) might be better served by someone taking advantage of your offer with a car with more miles on it, or waiting until someone gets to 5K before putting it on. Just a thought.

Regards,
Gordon

Originally posted by Efini 8
remember they are rated in PS - which is 1.25 hp.
um, dude, i think you're thinking of kW (which is closer to 1.3hp/kW).

a ps is about 0.93hp IIRC

I would also note that all of these dynos have been done in the hot part of the summer. One of the dyno charts specifically said that it was 95 degrees, most likely high humidity.

It is common knowledge that cold air basically contains more compressed oxygen, which makes much more power when it burns inside an engine. Hence...cold air intakes, etc. Just a cold air intake can add 10-15 horspower on some engines.

I notice an immediate power increase in my car on a cool (sub 70 degree) low humidity day, especially this summer, when one day it is 90 degrees, and the next it is 70. This is also why fuel economy goes down in the winter, because every car suddenly starts burning more fuel, but you get a little better performance.

I don't know how this translates on the dyno, but I almost guarantee you will get more horspower on a 60 degree day than on a 90 degree day.

The manufacturers must have some way to reconcile this issue...but a simple answer could very well be that Mazda tested the engine in the winter time, and all of you guys are testing it in the hot summer. I betcha when the manufacturers test them, it is in a completely controlled environment. Maybe someone out there has more specific knowledge on this and can comment.

Most dyno software is capable of correcting for climate conditions.

NOT saying it was done in the cases posted on this board, just that it can be done.

Hey Shawn!! ;)

Anyways, I hate to burst the bubble for you guys, but chances of the ECU leaning out after X miles is slim. After reading this thread, here are my thoughts...

I admit that I am not an expert on rotaries, but it would be hard to make up 30 hp on fuel tuning alone.

In addition being on a dyno wouldn't cause the ecu to freak out and dump so much fuel that you'd lose 30 hp. The ECU looks at several different conditions which determine fuel, but none of these include a little camera to see if the wheels are on a dyno or not... The only potential issue that you would see on the dyno is air intake temps higher than normal. This obviously results in thinner air, and thus less power. The ECU will actually PULL fuel in this case, not add fuel.

Adding fuel to the engine for "break in" is silly, and I find it a far fetched idea.

Last, I am surprised that among the cars tested no air/fuel data was reported, this would be more conclusive obviously. I am not sure what a target AFR would be for an N/A rotary, but checking that out would be helpful. Once again, even if you were running *super* rich (unlikely), a gain of 30 hp is a lofty goal.

I hate to say it but it sounds like Mazda will have to be fixing or compensating you guys somehow...

Good luck guys!!!

Chris

The June Best Car's (Japanese car mag) test results of the 250 ps vs. 210 ps versions of the RX-8 seem very odd. Both cars got about the same time for 0-100km/h (0-62mph) and 0-400m (Japan's 1/4 mi.) What's more the 0-100km/h of 7 secs is way off the pace for the 250 ps high power. Perhaps it's not just the US models with a power shortage...

http://www.artex.co.jp/Pages/Car/RX-8/magazine/Image/BestCar_03_6-26_03.jpg

hmmmmmmmmmmmm once again the plot thickens...

this is starting to get strange...

It could just be the magazine that tested the cars at the time or the conditions didn't lend themselves to good testing.

On the similar times for the low and high power versions, it could be that the Japanese low power version is a stick, which would alow for increased times as compared to the US spec auto.

yeah, there is a low power 5mt option in japan

Originally posted by cueball1029
It could just be the magazine that tested the cars at the time or the conditions didn't lend themselves to good testing.

On the similar times for the low and high power versions, it could be that the Japanese low power version is a stick, which would alow for increased times as compared to the US spec auto.

That is a lame excuse, what is equal for both cars is fair. If both were tested in similar conditions.

I'd settle for a lame excuse from Mazda, but instead we get nothing. Just standing around holding our dicks.

this isn't good.. :( Those numbers are essentially the same as the Prelude, 7.1/15.1 as they should be for the 5sp MT 210hp Rx-8 because it's about 100lbs heavier the the 5sp MT 200hp Prelude. BUT the 250ps 6spd should be a lot faster! WTF?!

Time to bring over the 210 HP version, drop the price $5k, everyone is happy.

Those times, if done with a high RPM clutch drop, are terrible for the 250ps version.

interesting.....:confused:

I don't know that we're that far off - I had a stoplight race with a friend who has been giving me a bunch of lip about how fast his SAAB Viggen is. His car was 6.7s 0-60, 14.9 1/4 mile stock and he has added a chip to up boost.

I absolutely destroyed him all the way through first and second, he was pretty well keeping the pace after that. Which would seem to fit pretty well with the advertised numbers for our cars.

Of course, that's with traction control off, 6500 rpm clutch drop and spinning tires most of the way through first gear... :)

Steven

Mazda REALLY need to get on top of this situation and fast. The negative publicity that could be generated if they don't do so might destroy the company. This is truly serious and alarming!

Originally posted by Quick_lude
this isn't good.. :( Those numbers are essentially the same as the Prelude, 7.1/15.1 as they should be for the 5sp MT 210hp Rx-8 because it's about 100lbs heavier the the 5sp MT 200hp Prelude. BUT the 250ps 6spd should be a lot faster! WTF?!
I used to own a '01 Type SH, and I have to say that the RX-8 is much faster feeling.

Originally posted by Lensman
Mazda REALLY need to get on top of this situation and fast. The negative publicity that could be generated if they don't do so might destroy the company. This is truly serious and alarming!

Maybe they deserved to be destroyed in the first place for sitting on their hands. Any company like this in general shouldn't last long in the playing field.

That Japanese car mag did the 1/4 mile run only 0.08 secs slower in the 210Ps car compared to the 250PS RX-8. I don't care if the 210PS vehicle was a 4AT or a 5MT, something is definitely wrong here - that 40PS difference is AWOL...

On the other hand it's good news for the low-power RX-8 owners - better than I expected.

Nissan 350z or even 2 seater VX220 turbo sounding even more tempting now

Originally posted by downshift
Maybe they deserved to be destroyed in the first place for sitting on their hands. Any company like this in general shouldn't last long in the playing field. Everyone needs to take a breath and take a step back and look at reality for a moment.

1) "Destroy the company"? I don't think so. Most people in the United States don't even know the RX-8 is out, and the percentage of those that do that know of any horsepower issues is infinitesimally small. Think about it, you have to know the RX-8 is out, what its HP numbers are, and the fact that it has dynoed low to date. I would say fully 99% of those Mazda is hoping would buy an RX-8 have no idea what a dyno even is. We here make up perhaps 1% of consumers, if we're lucky; you've got to remember the standard customer is one who will ask the salesperson about the car and will see the salesperson as an expert. I'm sure all of you have received as many "you know more about this car than I do!" responses from salespeople as I have.

2) Mazda does need to respond, but a response likely won't be coming this week or perhaps even this month. Big companies, domestic or foreign just don't work that way. They are likely researching the issue but after they do, they will have to determine exactly what is going on and run any response through legal several times. I'd say we'd be lucky to hear anything from them before October.

In the mean time hopefully a JDM RX-8 will be dynoed to see if it could be a U.S. Emissions issue, and the rotarynews folks will be able to look into the issue in more detail...

Originally posted by sburkett
I don't know that we're that far off - I had a stoplight race with a friend who has been giving me a bunch of lip about how fast his SAAB Viggen is. His car was 6.7s 0-60, 14.9 1/4 mile stock and he has added a chip to up boost.

I absolutely destroyed him all the way through first and second, he was pretty well keeping the pace after that. Which would seem to fit pretty well with the advertised numbers for our cars.

Hmm.. maybe it's a problem with only certain cars then? :confused: Until we get more dyno and 1/4 mile nubers from a drag strip, it's still all speculation.. but it's odd how at least some of the cars, both in NA and Japan are showing similar "missing power" traits.

Originally posted by Quick_lude

Hmm.. maybe it's a problem with only certain cars then? :confused: Until we get more dyno and 1/4 mile nubers from a drag strip, it's still all speculation.. but it's odd how at least some of the cars, both in NA and Japan are showing similar "missing power" traits. It's a major apologist point of view, but I tend to believe there may be something about the rotary that makes it difficult to characterize on a standard dyno test; that would certainly explain the difference between the numbers and what many feel in the "butt dyno."

I don't know if this had been brought up, but did anyone look at the torque perspective? For a high rpm car like RX-8 a small amount of torque could make a big difference in horsepower. For instance using the dyno result of ~180 hp at 8500 rpm that would work out to be about 111 lb-ft of torque. Let's just assume for what ever reason the problem is, green engine, ECU issues, mileage switch, hot climate....etc, we got back 10% of that torque later down the road,

111*1.1*8500 / 5252 = ~197 hp

That's pretty close to what it is suppose to be. Just a thought.

Originally posted by mr_digital_uk
Nissan 350z or even 2 seater VX220 turbo sounding even more tempting now Feel free..

Just for kicks, I called the Mazda customer service 800 number and asked the fellow about Mazda possibly overstating the HP numbers specified for the RX-8. His answer is: "Those HP numbers are not coming from Mazda. They are based on a US government-mandated test, and not the manufacturer". So I asked him whether the HP number we see on Mazda's own Web site is coming from the US government test and not Mazda? And he says, YES, Mazda does not make tests and so they literally don't know the number. I told him I find it hard to believe that a manufacturer would not know their car's power, but he sticked to his explanation. What BS... this is such a lame response.

There has been alot of talk and complaining in regards to the horsepower of the rx8. I am a dealer and I hope I can clear up any bad remors that are going around. From my understanding it has alway been 210 hp in the automatic and 250 hp in the 6 speed. The reason for this is by design the rotory engine is a very high reving engine. Automatic trans. can not handle the high revolutions of the engine. Mazda instead place more torque in the range where the average automatic driver would use it.
Thank you

people are complaining because the 6-speed version is only showing up with lots less horsepower.

Haven't heard too many complaints about the automatic other than the one fellow who thinks it is slow.

You run into the "slow" problem with lots of automatics though, especially turbocharged cars, or vehicles with some variation of valve timing (or peripheral ports). can't dump the clutch and the gearing is too broad, too much load on the engine in the low-horsepower areas, etc, etc. not a problem with any of the cars, just something to live with in exchange for the convenience.

blah blah

my .02

NOT just for kicks, on 8/2, I wrote the following to Mazda from their web site where owners can submit a question (you must include your VIN# as well as personal particulars):

---------
"I bought my RX-8 7/18/03 and I am generally happy with it although I have only 450 miles so far. However, I read with increasing concern the growing controversy concerning the fact that several owners to date have not been able to dyno any car to exceed approx 185 rear wheel horsepower. This is nowhere near the advertised HP of 247 unless there is an approximate 25% drive train loss.

In any case, whatever the cause, as this situation develops, something seems to be wrong here, the only question is what, and why this is occurring, and what is the appropriate remedy. Mazda's recent experience with the Miata's falsely stated HP rating should have heightened Mazda's engineers attention to such detail, one would like to believe, so I wanted to get your opinion on what EXACTLY is going on in this situation with the RX-8 and apparent low HP output? Can you please comment? "
---------

On 8/2 I received an automated reply, saying they are closed on weekends, but with a promise of a response "as quickly as possible".

Will post when I get that real reply. I think we owners should be individually asking 'what's up' to Mazda so they know there are those who do care about what they paid their money for, and aren't particularly happy with this coming to light from owners, rather than from Mazda themselves.

I find it IMPROBABLE if not IMPOSSIBLE that Mazda Japan does not know what we are just finding out on our own. ***Research an answer my foot!*** They've had this engine (and car) under development for several YEARS, yet a few lay enthusiasts can determine WITHIN DAYS some anomoly that makes all officaldom that is willing to speak offer a collective 'Really???"

Let's get real here! Still lovin my car ... but Sheezzz! :(

Originally posted by Spin9k
I think we owners should be individually asking 'what's up' to Mazda so they know there are those who do care about what they paid their money for, and aren't particularly happy with this coming to light from owners, rather than from Mazda themselves.

I agree! We should be flooding Mazda with letters, not posting "alleged" issues with the car on the internet for all eyes to see.

I called the 800 number yesterday and the person gave me their extension number so I could check back with them specifically at the end of this week since his boss told him that Mazda was looking into this and knew about the concerns. This rep had actually read some of the posts on this forum and was eager to find out what (if anything) the issue is also.

I submitted a question per email last week and got this response today:

"Thank you for contacting Mazda North American Operations. I appreciate
the opportunity to respond to you.

In regards to your inquiry, please understand that the tests that you
referred to were not conducted by Mazda and we can not substantiate the
claims of independent testing, although we are looking into this
matter. Currently, the information that we have supplied remains. No
engine-break in has been noted."

You completely missed the point. The 6-speed version is dynoing out about 20 HP below where it should be if it had 250 HP at the crank. Where are those missing horsies?

anyone considered the effect the weight of the 18'' wheels might have? I say this because mazda's claim of 247 would be from the crank, not taking the wheels into account. Now, the wheels don't explain such a massive precieved loss in HP, but I'm wondering what they weigh in at.

In addition, it would appear Mazda was testing and tweaking the car to the very end, hence all the pre-production literature says 250 HP with a "*" and a comment stating 250 was the target HP. In the end, they ended up rating it 247, which is pretty specific, I mean, if the car has dyno'd out fine and they'd left the stat at 250, I doubt anyone would have noticed. So it makes me think that something else must be going on.

Originally posted by sburkett
...

I absolutely destroyed him all the way through first and second, he was pretty well keeping the pace after that. Which would seem to fit pretty well with the advertised numbers for our cars.

...



I imagine the difference in the first 2 gears was due to RWD versus FWD on the Viggen. Once traction no longer became a factor, power to weight ratio of the Viggen seemed to be close to the 8 (not considering aerodynamic drag). What's the curb weight & hp of a chipped Viggen?

Originally posted by wakeech

um, dude, i think you're thinking of kW (which is closer to 1.3hp/kW).

a ps is about 0.93hp IIRC

Actually, it's 0.9863hp I remember because bwob said that the 280PS "target" engine was the 250HP with the difference being PS to HP and DIN HP to SAE HP conversion. I spent some time checking before saying he was wrong:
SAE(US) = kW * 1.341 (american) @ 25 deg C, 99kPa)
STP(US - dyno) = 1.341 @ 15.5 degC, 103,3kPa) [approx 4% higher than SAE]
DIN = kW * 1.360 (german) @ 20 deg C 101.3kPa
ECE = kW * 1.360 @ 25 deg C, 99kPa
JIS (metric adopted from SI) = kW * 1.333 (defined as 0.75kW)

But nevertheless he posted on miata.net recently that the reason he stopped posting on rx8forum.com was because people here said he was wrong :(

-pete

I am sure this is a stupid question, but is there any chance that in the heat of the moment these cars were dyno'ed with the DSC still partially engaged?

Yes, if memory serves one of the very first runs may have had the DSC partially on. The DSC and the other electronic gee-gaws on this car give me some pause about the dyno results. Like the throttle by wire, I've seen a few people suggest that a throttle position reading should be taken during a run to verify that it's really wide open, but I don't think anyone's done it yet.

By the way, nice JPS Europa. A buddy of mine has a beautiful JPS that looks almost the same. Beautiful little cars, and 1,500 lbs wet.

Just wanted to say that it's nice to see RN & Shawn lending their expertise to this problem and I look forward to reading the results as this gets sorted out.

This will be somewhat offtopic post, and I'll probably just be adding gasoline to the fire here... and in fact this makes things more confusing..

Found some HP calculations and calculators on google... Results very greatly, as true calculations depend on a ton of variables that these calculators don't take into consideration.


http://www.battleoftheimports.com/classes/battlecalc.htm sais:
RX8 which weighs about 3180 pounds should complete the 1/4-Mile in about 14.9 seconds, if you can produce about 190.00 HP at the wheels, or about 247.00 HP at the flywheel.


http://www.mustangworks.com/analyzer.html (yah yah..) said:
Best 1/4 Mile ET: 14.9
Best 1/4 Mile MPH: 94.3
Your car weight: 3180

Peak Horsepower: 190
Average Horsepower: 208


Conclusion, even with track numbers and time slips, it will be hard to calculate percise HP numbers.

Then theres also an option where you input your:

1. Vehicle Model
2. Vehicle weight (w/drive)
3. And Quarter Mile Time

And it calculates your hp based on that so i entered

1. Mazda Rx8
2. 3200 (estimate)
3. 14.9 (Road and Track)

And here is the response i got:

Horsepower Based On 1/4-Mile E.T.
Your Mazda Rx8 which weighs about 3200 pounds should complete the 1/4-Mile in about 14.9 seconds, if you can produce about 191.20 HP at the wheels, or about 248.55 HP at the flywheel.

Originally posted by rpm_pwr



But nevertheless he posted on miata.net recently that the reason he stopped posting on rx8forum.com was because people here said he was wrong :(

-pete

i'm surprised to hear that bwob is purported to have said something like that. do you have a link? as you can see in this link (http://www.rx8club.com/search.php?s=&action=showresults&searchid=94627&sortby=lastpost&sortorder=descending) to a search of his posts he hasn't posted here in quite some time and if you read thru the posts there is no discernible argueing with him.

Originally posted by zoom44


i'm surprised to hear that bwob is purported to have said something like that. do you have a link? as you can see in this link (http://www.rx8club.com/search.php?s=&action=showresults&searchid=94627&sortby=lastpost&sortorder=descending) to a search of his posts he hasn't posted here in quite some time and if you read thru the posts there is no discernible argueing with him.

Here's the thread where he mentions the RX8 forum at Miata forum...

http://www.miataforum.com/ubb/ultimatebb.php?ubb=get_topic;f=11;t=012624#000002

It doesn't sound like he was REALLY offended, but maybe a little, and of course we don't know what sort of private msg or emails were sent his way.

ahh so people who didn't know who he is (like myself when i first saw a post of his) or people who knew who he was supposed to be checked him to make sure who he was(and not just some anonymous person grabbing his moniker) so that his info could be relied upon. sorry if bwob had a problem with someone trying to authenticate a source and i hope he does indeed post his thoughts in here again when he has time. it would be most welcome by many of us here.:)

thanks!

Originally posted by zoom44
ahh so people who didn't know who he is (like myself when i first saw a post of his) or people who knew who he was supposed to be checked him to make sure who he was(and not just some anonymous person grabbing his moniker) so that his info could be relied upon. sorry if bwob had a problem with someone trying to authenticate a source and i hope he does indeed post his thoughts in here again when he has time. it would be most welcome by many of us here.:)

thanks!

... wow... that was a mouthful...:confused:

:o yeah i get wordy sometimes:o now back to the actual topic!

Originally posted by Tamas
Just for kicks, I called the Mazda customer service 800 number and asked the fellow about Mazda possibly overstating the HP numbers specified for the RX-8. His answer is: "Those HP numbers are not coming from Mazda. They are based on a US government-mandated test, and not the manufacturer". So I asked him whether the HP number we see on Mazda's own Web site is coming from the US government test and not Mazda? And he says, YES, Mazda does not make tests and so they literally don't know the number. I told him I find it hard to believe that a manufacturer would not know their car's power, but he sticked to his explanation. What BS... this is such a lame response. Don't be too hard on Mazda; if you call the 800 number for any car company you're going to get someone in a call center making $5/hour who only knows what's in the scripts before them and any further information (like that above) is probably an ad lib to avoid sounding clueless. (With the end result that they of course sound more clueless than ever...)

Apologies for going OT here.

Originally posted by zoom44

he hasn't posted here in quite some time and if you read thru the posts there is no discernible argueing with him.

http://www.rx8club.com/showthread.php?threadid=109

Is where I pulled him up on the 280 vs 250 thing.

http://www.rx8club.com/showthread.php?threadid=39&perpage=15&pagenumber=1

Is where he mentions the "pair of specifications" (referred to on the miata.net post. People do question him on it, but it hardly reads as rude does it? I think it was all pretty mild given on a few people knew who he was.

Nevertheless with the benefit of hindsight, he was spot on (no surprise!) and we are still *yet* to see a 280ps factory rx-8.

-pete

Hi Guys,

I've been lurking here for some time, and I enjoy your posts. As the owner of an MP3 Protege, let me tell you about my break in experience. I own the car because I do a LOT of driving, and I need something practical and economical, but I'm a dyed in the wool car nut who craves lateral cranial fluid displacement every day I drive. Otherwise, the car is not worth owning.

I trust my credentials are in order!

When I first got the MP3 I couldn't figure out why my mileage was so bad. I couldn't beat 22 MPG no matter what! It wasn't until I hit about 10,000 miles that I finally obtained 30 MPG, which is what a silly ass Jap four banger with 140 horse SHOULD get. But it sure took time. Credit the tight production tolerances on these new engines for that.
I now have 25K on the odo, and the engine is looser and stronger than ever. It revs much easier than it did before, and it's like owning a work in progress. Chances are, the RX-8's need some time down the road for everything to settle in. This car had a very long time in development. I first saw the 8 at the NY Auto Show three years ago (albeit a prototype with push button start, etc.) so I doubt there are any surprises lurking. So give it a chance. My feeling is the cars given to the magazines were probably a bit "massaged" to duplicate the experience of a broken in car.

However, I have been wrong once or twice in my life. Well, maybe three times.

What mileage do you have on yours cars before you all eagerly put your cars onto a dyno..and how was it driven? Perhaps being RWD the actual drivetrain loss of 30% is more realistic than 15 to 17%? The only way to accurately find that out would be to dyno the engine in the car at the wheels and with the engine out of the car as well.
A properly broken in rotary engine will produce more power across the engines RPM range and will have a longer service life. This means no revving pass 4000RPM for the first 500 miles and from there up to 1000 gradually increasing the RPMs but NEVER approaching redline. After 1000 miles short burst towards redline for another hundred or so miles.
It would be fun to stick an 8 with my near stock 20 year old FB with over 160K miles on it, because of your unwarranted desire to produce big power numbers right away.

I find Mazda's reply that "we don't do the test, those are not our numbers" kinda shady. It looks like they are searching for a scape goat with that reply. I mean, hello, they have been R&D'ing this engine for years now, and they dont know the numbers it puts out..yea..sure. I hope this isnt the case though, because crediblity is tough to get back once it's gone.

I think they are talking about the fact that a few guys in the US getting 'some' numbers on different dynos on different days is not something that they feel comfortable commenting on, and that's perfecty understandible.

They ain't gonna use our research to make a decision or determination of a problem. They'll be doing their own research.

http://www.sportcompactcarweb.com/editors/technobabble/0112scc_technobabble/


Looks like there is an explanation, after all. [COLOR=darkblue]

Originally posted by RacerX7FB
Perhaps being RWD the actual drivetrain loss of 30% is more realistic than 15 to 17%? The only way to accurately find that out would be to dyno the engine in the car at the wheels and with the engine out of the car as well.


A 30% drivetrain loss on a 2wd vehicle would be horrible even for an AUTOMATIC.

A 200hp auto Eclipse GT dynos at about 150-155hp to the wheels (a 20-22% loss). A 200hp mt Eclipse GT dynos at 165-170hp to the wheels (a 15-17% loss). Obviously dyno numbers vary depending on conditions and the type of equipement used, but that's a pretty accurate assesment of what the cars put out stock.

The RX-8 is supposed to put out 50 more ponies than the Eclipse, yet it's only putting 10 more hp to the ground.

The problem could be any number of things, but drivetrain loss isn't one of them. Do not fool yourself into thinking that the numbers being put down are "normal" for a 247hp engine.

The greatest thing about debates like these is that we're all factually un-armed at the moment.

None of us knows what IS or ISN'T part of this equation yet, so ruling out something that clearly COULD be playing a part in this situation makes little sense.

In response to my inquiry to Mazda regarding the HP controversy, I received this reply on Friday 8/7:

"Thank you for contacting Mazda North American Operations.
I appreciate the opportunity to respond to you.

In regard to your inquiry, Mazda is aware of the comments
floating around on the Internet regarding RX-8s not meeting
the posted horsepower rating, and we are looking into the
matter. However, we stand by the current states power levels:
247hp for the manual transmission cars and 207hp for the
automatic cars.
...

...
Again, thank you for contacting Mazda.

xxxx xxxxx
Specialist, Customer Assistance E-Business"

This is GOOD!

1. Mazda have officially confirmed that they are aware of the issue: therefore they'll have to prove it's not an problem, fix it or compensate owners. I presume they are legally committed now that they've acknowledged the issue?

2. They intend the cars to match the stated power outputs: therefore they can't get out of this on a technicality if there DOES prove to be a problem.

However: if it was an ECM mapping issue and deliberate then don't you think they'd have simply said so by now? I would have.

Sorry to speculate again. I know that a lot of people are getting sick of idle talk but feedback from Mazda is quite a milestone.

I think we should adopt a "wait & see" approach.

However, we should also not allow Mazda to drop the issue either.

Level headed approaches are whats needed...........:)

This e-mail from Mazda also means they did not purposely detune the RX-8's at port to meet long-term emissions.

Originally posted by MP3Guy
http://www.sportcompactcarweb.com/editors/technobabble/0112scc_technobabble/


Looks like there is an explanation, after all. [COLOR=darkblue]

Good article. It's great that Sport Compact Car measures the HP at the wheel during their review tests. However, when they tested the RX-8, the measured wheel hp was inconclusive because of the defective engine (ports not opening).

I do not know if Sport Compact Car has done a review of a "fixed" RX-8 since that last test, and has provided their "conclusive" rating for the hp at the rear wheels.

Hey, new poster here

What we all need to think about is, the fact that the two engines in each version are IDENTICAL. There is no CAI, no turbo, no mods other than your right hand.

And yet, we get a 40 hp increase? Granted this IS a very high revving engine, but 40 is still too much. This just immediately jumped out at me because they are the same damn engine yet you get waaay too much for the MT. Looking at the specs I said to myself "why in the hell would you buy the AT if the MT is the same price?!(almost)"

Im going to make 2 suggestions for solutions
1.) Mazda wanted to make buyers of the MT who are always performance-minded feel special because they are making lots of HP. Im betting they are suprised as hell that since the first few RX-8s are released in the US, we already threw em on a dyno.

2.) Theres a mechanical explanation. Im betting on a combination of 3 things:
ECU Remap
Break in
Lack of AIR on dynos.

Lack of air seems to be omissed from many of your arguements. But lets not forget how the RX-8 is designed. It has the 5 point intake system, with a generous intake area. Now on a Dyno this thing will be SUCKING AIR, especially at the mega Rpms the 8 can get to. Its quite simple...

The volume of air is not sufficient at very low speeds or when the car is not moving. This explains the lack of low end power and torque.

I suggest you find a bunch of fans and put them aimed at the car when dynoing. This will at least try and simulate the volume of air this car is going to take in at driving speeds.

Autos are horrible on performance, yeah. But on similar cars like the RSX, the drivetrain loss is minimal. A 25%+ loss is UNACCEPTABLE.

Mazda is obviously trying to dodge their way out of this. Given their history with the Miata, im doubtful.

Now I know test results vary but Im looking at the consumer guide results for the RSX are as follows:
Type - S (200hp, similar weight etc) does 0-60 in 7.8. Again thats their test, not what acura says.

Now most articles I have seen claim the AT does a few tenths faster than that! What? Its putting down the same if not less power than an RSX MANUAL and its faster? No.

fishy, is it not?
Im not in the market for an 8 right now, but nissan just sold another Z if they dont fix this issue within the next few weeks.

The engines in the Auto and Manual are not identical. The maunual trans engine has a different intake configuration with two extra intake ports available for high RPM running

suggest you find a bunch of fans and put them aimed at the car when dynoing. This will at least try and simulate the volume of air this car is going to take in at driving speeds.

I asked about this on another thread and was told they did have a fan or fans to supply air while on the Dynojet. So...
Guess we'll just have to wait and see. Sports Compact mag had the most logical explanation I've seen yet. Some cars just don't work properly on a Dyno for any number of different reasons particular to the car being tested.

Originally posted by rxphink
The engines in the Auto and Manual are not identical. The maunual trans engine has a different intake configuration with two extra intake ports available for high RPM running

Wow! The civic boys will be all over this one

an intake that gives you 40 more hp!

Originally posted by TybeeRX-8

I asked about this on another thread and was told they did have a fan or fans to supply air while on the Dynojet.
That was probably me.. While I can't speak specificallly for that place, any dyno place worth its salt has at least one fan under the air intake to simulate road conditions. If the lack of air was the issue with low dyno numbers, how do you explain the Japanese mag 1/4mile numbers which were virtually identical for the low power 5mt and high power 6mt versions?
I would like to see some real 1/4 mile numbers from the drag strip, none of these "I raced my buddy" on the street and got a 14.8 stuff.

Originally posted by Xavier


Wow! The civic boys will be all over this one

an intake that gives you 40 more hp!

Not a different intake, that would imply that the differences are before the throttle body.

The MT has a different intake system, this includes intake runners and intake ports in the engine.
Like so:

http://us.f1.yahoofs.com/users/27decd74/bc/RX-8/__hr_intake_conifgs.jpg?BClirN_AqnW3Bp0u


This is how it works in the high power engine:

http://www.rx8forum.com/attachment.php?s=&postid=91911

Red 6-spd, 2650 miles, completely stock.

Dyno: Dynapack 2000 chassis dyno - hydrostatic loading, hub dyno (wheels removed, dyno bolted directly to drive hubs).

Power (SAE corrected) output: 189 hp @ 8179 rpm
Torque output: 138.5 lbs-ft @ 5918 rpm

If someone can host pictures, I will email the scans to you, as well as comparisons with a typical S2000 and a typical 350Z, two cars which share similar drivetrain layouts and power levels.

Just for reference, the RX-8 curve looked just like I would expect it too, right up until 6000 rpm where things got wierd. Compared to a typical S2000, it was down 21.5 whp at peak. Compared to a 350Z, it was 63.8 whp at peak. In either case, this would suggest an actual power output of around 220 crank hp. Mixture was rich, but only about a half point richer than the average S2000 - so while rotaries do tend to be a little more sensitive to mixture than piston engines, they aren't _that_ much more sensitive.

Another interesting point - My scan tool could not read anything from the ECU. I've tested several OBDII Mazdas, including an MP5 a few months ago and had no problem pulling OBDII data, so this was interesting. The scantool was receiving power from the port, but it kept telling me there was no signal and to check if ignition was on.

More info coming.

SC

Originally posted by ChurchAutoTest
(wheels removed)

Power (SAE corrected) output: 189 hp @ 8179 rpm
Torque output: 138.5 lbs-ft @ 5918 rpm


Take off those big 18s and it makes a difference. It might explain something... similar cars with smaller stock tires dyno better ex: RSX

was the AFR around 12?

cause people are saying that it should be A LOT closer to 14, like 13.7 or even 14.1 or something like that

anyway, thats very strange with the ECU thing... is it possible its using a new version or something along those lines?

Originally posted by P00Man


anyway, thats very strange with the ECU thing... is it possible its using a new version or something along those lines?

More fuel to the ECU fire, considering they were programmed at the docks. Im thinking Mazda didnt meet emissions or something along those lines... So they got reprogrammed and had to be locked? so the dealers couldnt revert back to the old ones.

Originally posted by ChurchAutoTest
Red 6-spd, 2650 miles, completely stock.

Dyno: Dynapack 2000 chassis dyno - hydrostatic loading, hub dyno (wheels removed, dyno bolted directly to drive hubs).

Power (SAE corrected) output: 189 hp @ 8179 rpm
Torque output: 138.5 lbs-ft @ 5918 rpm

If someone can host pictures, I will email the scans to you, as well as comparisons with a typical S2000 and a typical 350Z, two cars which share similar drivetrain layouts and power levels.


SC

Thank you very much!

Basically, and correct me if I'm wrong, you got about what we've seen so far?

How big are the pictures you have. I have a bit of room left on my site, I maybe able to post them for you.

"So they got reprogrammed and had to be locked? so the dealers couldnt revert back to the old ones." - Xavier

then wouldnt it probably say something like "no signal" or "locked" instead of "check ignition"?

my guesse by the "check ignition" thing is that the scantool "simply" couldnt recognize the ECU, and therefore "concluded" that the ignition was off

"Im thinking Mazda didnt meet emissions or something along those lines... " - xavier

and if they reprogged to meet emissions, then why the rich mixture, that doesnt really make any sense, the engine is running so rich its practically blowing gass droplets out of the muffler

that said i still think the best explaination is the the break in fuel map theory that we have, either that or that it cant be dynoed well, which also can be thrown away given the results Mr. Church (is it Mr. Church?) posted due to the type of dyno he used which would have negated those previous possible effects by bolting straight to the drive hubs, which i imagine would eliminate slip and thus eliminate the ECU trying to negate that slip in order to save the driver going off his desired course, in other words, i feel that this particular type of dyno would "bypass" the TCS and DSC systems

OK, I've been reading about this horsepower issue with great interest, since I'm about to plunk down $30,000 on this car.

I know nothing about this stuff, didn't even know what a dyno was before RX-8 Forum. But here's something that seems to make sense to a "layperson."

ChurchAutoTest dyno'd the RX-8 at 189 HP and noted "things got weird" at around 6000 rpm. Now, doesn't Mazda ask that we break the cars in by keeping them under 7000 rpm for the first 1000 miles (or something to that effect)?

I think this might lend creedence to the break-in ECU mapping theory. Maybe Mazda doesn't trust us to break the car in the way it needs to be done.

Originally posted by loco4rx8

ChurchAutoTest dyno'd the RX-8 at 189 HP and noted "things got weird" at around 6000 rpm. Now, doesn't Mazda ask that we break the cars in by keeping them under 7000 rpm for the first 1000 miles (or something to that effect)?


That car had over 2500 miles on it. Well beyond the manufacturer's prescribed break-in period.

Originally posted by Keeper


That car had over 2500 miles on it. Well beyond the manufacturer's prescribed break-in period.


Yeah, I know. But some folks here have speculated that it might take 5,000 miles for the ECU to "remap." I dunno.

Originally posted by Xavier

And yet, we get a 40 hp increase? Granted this IS a very high revving engine, but 40 is still too much.


Yes, higher revs CAN yield that much of an HP increase. In fact, you can get that much of an HP increase without increasing the torque output of the engine at all.

HP is a function of torque --> HP = TQ*rpm/5252 rotations. Most people think of HP as "power" or "force", but it isn't -- it's a measure of work. "Work", in physics terms, is a force applied over time. Torque is the force exerted by an engine. The more often you apply the force, the more work you do. The faster the engine revs, the more often the force is applied, and the higher your work/hp number is. I could get into where the 5252 rotations comes from, but then this post would get even more boring than it already is.

So let's translate this to a real world example. In this case, let's relate it to the dyno that was just posted.

If you were putting out 140ft/lbs of torque at 6000rpm, you'd be making 159hp. If you were putting out 140ft/lbs of torque at 8000rpm you'd be making 213hp.

That's actually a 50hp gain that you get just from making the engine spin faster.

Obviously, the trick is to keep the torque up at higher revs, which is what the problem here is...when the intake ports switch, torque output drops drastically instead of staying flat.

Originally posted by Xavier
Wow! The civic boys will be all over this one

an intake that gives you 40 more hp! Not just an intake. Because of the way that a rotary works, altering the placement of the intake ports alters the timing and duration of their opening. So when the second and third ports open as the revs rise, the effect is not dissimilar to Honda's VTEC, as the extra ports incrementally alter the "intake valve" timing and duration. (But without the obnoxious VTEC din.)

Yes, the results were in line with what others have been reporting.

I have 3 GIF files each about 150k in size. I can email them to you if you like.

One displays the RX8 compared to an S2000 (hp and tq), another shows the same comparison between an RX8 and 350Z. Finally, there is an A/F ratio comparison between an RX8 and S2000. Please note that on the charts it says "flywheel" hp. That is not correct. The Dynapack sw allows you to enter a correction factor for transmission losses (you will see it on the charts as "TCF"). We don't attempt to correct for this, so the factor is left at 1.0 which means the numbers you see are what was measured at the hub.

Someone else mentioned comparing an RSX. I didn't think that was totally valid for a comparison since it is a transverse FWD drivetrain, something more efficient than a longitudinal front/rear setup. However, the average stock RSX-S produces about 172 whp on my dyno, which is 17 less than the RX8 - again supporting the 220 crank hp number.

I think the RX8 compared to the S2000 is the most valid comparison. The RX8 is rated at 6 lbs-ft of torque more and 7 hp more. Both cars have high revving powertrains, similar rear end ratios, similar layouts, etc. Up until 6000 rpm the RX8 is handily ahead (as expected, it displaces more and has the variable intake system). The curve is smooth and steady. And then at 6000 it gets rough and takes a dive while the S2000 curve takes off. If the RX8 was performing as advertised, I fully expected the two curves to be virtually parallel at high rpms, with the RX8 being slightly higher of course.

Hopefully Romano will be able to post the charts up for everyone to see.

SC

Originally posted by RomanoM


Thank you very much!

Basically, and correct me if I'm wrong, you got about what we've seen so far?

How big are the pictures you have. I have a bit of room left on my site, I maybe able to post them for you.

Originally posted by ChurchAutoTest
Yes, the results were in line with what others have been reporting.

I have 3 GIF files each about 150k in size. I can email them to you if you like.

Hopefully Romano will be able to post the charts up for everyone to see.

SC



450k..no problem I have 650K left of space:)

I can make some room if need be.

vrooom@verizon.net

send them all at once, I have broadband.

I will put them up on the server and then e-mail you back the URL address so you can post them the way you want in this thread or anywhere else.

Regarding some of the other questions raised, many will be answered when the charts are posted, but...

The average AFR was right around 12:1. This is not optimal for power, but not unusual in high revving, high performance engines. By comparison, over the same rpm range a Honda S2000 averages about 12.5:1.

The scantool returned a "no signal, check ignition" response after about 1-2 minutes of trying to make a connection. As I said, it was able to power up from the port, but was not able to interface with the ECU. The only other time I've seen anything similar was when I tried to link up with a European market Honda development ECU from a pre-production car.

The TCS was fully disabled (hold button for 5-10 seconds). However, the Dynapack would not preclude the same dyno issues that could happen on a roller dyno as one set of wheels is spinning while the others are not.

In light of the performance under 6000 rpm, which looks just like one would expect based upon rated power, published numbers, etc., I would have to say that something is holding back power above 6000 rpm. Whether its a wheelspeed based issue on the dyno, or an ECU issue, intake issue, etc. I don't know.

One thing I did notice were two vacuum ports on the lower part of the intake manifold, capped with black rubber vacuum caps. Any idea what those are for?

SC

on every injected rotary I've seen, Mazda leave a few spare nipples to connect gauges / etc to.

BTW Nice work ChurchAutoTest.

-pete

Originally posted by ChurchAutoTest
Red 6-spd, 2650 miles, completely stock.

Dyno: Dynapack 2000 chassis dyno - hydrostatic loading, hub dyno (wheels removed, dyno bolted directly to drive hubs).

Power (SAE corrected) output: 189 hp @ 8179 rpm
Torque output: 138.5 lbs-ft @ 5918 rpm

If someone can host pictures, I will email the scans to you, as well as comparisons with a typical S2000 and a typical 350Z, two cars which share similar drivetrain layouts and power levels.

Just for reference, the RX-8 curve looked just like I would expect it too, right up until 6000 rpm where things got wierd. Compared to a typical S2000, it was down 21.5 whp at peak. Compared to a 350Z, it was 63.8 whp at peak. In either case, this would suggest an actual power output of around 220 crank hp. Mixture was rich, but only about a half point richer than the average S2000 - so while rotaries do tend to be a little more sensitive to mixture than piston engines, they aren't _that_ much more sensitive.

Another interesting point - My scan tool could not read anything from the ECU. I've tested several OBDII Mazdas, including an MP5 a few months ago and had no problem pulling OBDII data, so this was interesting. The scantool was receiving power from the port, but it kept telling me there was no signal and to check if ignition was on.

More info coming.

SC

One displays the RX8 compared to an S2000 (hp and tq), another shows the same comparison between an RX8 and 350Z. Finally, there is an A/F ratio comparison between an RX8 and S2000. Please note that on the charts it says "flywheel" hp. That is not correct. The Dynapack sw allows you to enter a correction factor for transmission losses (you will see it on the charts as "TCF"). We don't attempt to correct for this, so the factor is left at 1.0 which means the numbers you see are what was measured at the hub.

Someone else mentioned comparing an RSX. I didn't think that was totally valid for a comparison since it is a transverse FWD drivetrain, something more efficient than a longitudinal front/rear setup. However, the average stock RSX-S produces about 172 whp on my dyno, which is 17 less than the RX8 - again supporting the 220 crank hp number.

I think the RX8 compared to the S2000 is the most valid comparison. The RX8 is rated at 6 lbs-ft of torque more and 7 hp more. Both cars have high revving powertrains, similar rear end ratios, similar layouts, etc. Up until 6000 rpm the RX8 is handily ahead (as expected, it displaces more and has the variable intake system). The curve is smooth and steady. And then at 6000 it gets rough and takes a dive while the S2000 curve takes off. If the RX8 was performing as advertised, I fully expected the two curves to be virtually parallel at high rpms, with the RX8 being slightly higher of course.

Regarding some of the other questions raised, many will be answered when the charts are posted, but...

The average AFR was right around 12:1. This is not optimal for power, but not unusual in high revving, high performance engines. By comparison, over the same rpm range a Honda S2000 averages about 12.5:1.

The scantool returned a "no signal, check ignition" response after about 1-2 minutes of trying to make a connection. As I said, it was able to power up from the port, but was not able to interface with the ECU. The only other time I've seen anything similar was when I tried to link up with a European market Honda development ECU from a pre-production car.

The TCS was fully disabled (hold button for 5-10 seconds). However, the Dynapack would not preclude the same dyno issues that could happen on a roller dyno as one set of wheels is spinning while the others are not.

In light of the performance under 6000 rpm, which looks just like one would expect based upon rated power, published numbers, etc., I would have to say that something is holding back power above 6000 rpm. Whether its a wheelspeed based issue on the dyno, or an ECU issue, intake issue, etc. I don't know.




The Graphs from ChurchAutoTest:

RX-8 v. 350Z Power and Torque
http://mysite.verizon.net/romano.michael/RX8-350Z.gif
Link: http://mysite.verizon.net/romano.michael/RX8-350Z.gif

RX-8 v. S2000 Power and Torque
http://mysite.verizon.net/romano.michael/RX8-S2000pwrtq.gif
Link: http://mysite.verizon.net/romano.michael/RX8-S2000pwrtq.gif

RX-8 v. S2000 Air/Fuel Ratio
http://mysite.verizon.net/romano.michael/RX8-S2000AFR.gif
Link: http://mysite.verizon.net/romano.michael/RX8-S2000AFR.gif

dude i can barely read those graphs, can you enlarge them?

but I do see from what I can see, that at 6000rpm the power 'leveled off' instead of keep climbing, in the RX-8/S2000 HP chart.

that's definitely NOT what the engine should do

Originally posted by ZoomZoomH
dude i can barely read those graphs, can you enlarge them?

but I do see from what I can see, that at 6000rpm the power 'leveled off' instead of keep climbing, in the RX-8/S2000 HP chart.

that's definitely NOT what the engine should do


By your command:p

What would happen if instead of an ECU mapping issue there were some kind of US-production derived obstruction in the tertiary intake path, or a lack of resonance? does this make any sense?

Church, did you notice change dramatically from below 6000 rpm to above 6krpm?

becuase the other AF charts showed more or less "normal" or "correct" ratios below 6000 and then dramatically changed to those more abnormal ratios above 6k or there abouts

i cant really read the AF ratios in those shots, so thats why i ask

If you'll closely at the new, enlarged pics, you'll see that the RX8 starts off relatively lean, but by 4000 rpm has dropped down into a richer state that is more in tune with how modern cars run at full throttle.

Many modern ECU systems actually try and run near stoichiometric for short applications of full throttle by using cheap widebands as the primary O2 sensor. We've seen this on Acura RSXs and even some of the newer Ford products. Ostensibly this is to improve emissions performance, but once the ECU realizes you intend to keep your foot in it (time based? Who knows) it goes to a safer WOT mixture. In the case of the Dynapack, we always do a loaded stabilization before the run begins, so the car is being held at WOT for 2 seconds at 2000 rpm before the ramp begins. On a Dynojet, you're accelerating as soon as you go WOT, so any attempts to run stoich (if time based) will go rich later than we did on this test.

I think its important to point out that on a NA engine, going from 12:1 to 13:1 is not going to free up much power. 2-3% is a normal number. The mixture is not the culprit here, something else is cramping the top end power.

SC

By the look at how quickly the curve falls off after 6000 I would have to say that timing and intake restrictions are the two most likely culprits.
Did you guys happen to notice if the throttle plate was opening fully?

The A/F is still too rich it should be in the 13's, this is based on previous experience with N/A rotaries. My old '91 would run in the mid/high 13's at the top end and this is with an even less efficient port design. The renisis' port design is bay far better at scavenging the unburnt A/F mix and sending it back around to be burnt again, so I would expect the A/F readings to be much more lean in with the renesis. I would also expect them to be a bit different based on the fact that the renesis uses speed density vs. the old N/A 13B's mass air system since the renesis has the ability to compensate for barometer and temp.

Now another question, wher are the A/F ratios being measured?
Are you removing the stock primary O2 sensor?
If so this might be a problem since the stock primary O2 sensor looks to be a wide band sensor. By removing this from the pipe the ECU may be freaking out and dumping fuel. If your getting it from the tail pipe, then damn it must be RICH before the cat.
With the wide band stock sensor the car would be more likely to try and manage the A/F ratio all through out the rev band.

I have noticed a lot of debate concerning the validity of a dynojet because of unknown drivetrain loss.

Rotary News posted an article here:

http://rotarynews.com/view.php?id=198

The subject of the article deals with a company developing aftermarket parts for the Renesis engine.

Pictures in the article show the engine attached to a brake type dyno.

Has anyone heard the results of this test?

you guys might find this intresting regarding not being able to get info from a scan tool thru the ecu.my last car was a svt focus and ford has a new encripted program they have in this car only.have spent alot of time on svt forums and found that not even diablo or superchips have been able to get into it to build performance chips.it is a flashable system that dealers only with special softwear can reflash the system.my svt went thru 4 reflashes in 7 months with the supposed new and better program and each time the car was diffrent.this may or maynot be the same or similar system in the rx8 but if this is its a very advanced computer and im thinking(hoping) that we will get are power back wether its automatic after a set mileage or we have to go in for a ecu reflash,just hope they let us know soon so we can talk about all the great things this car can do. :D

maybe the ecu is restraining power to protect the engine from over heating.

1 rx7s have overheated and alot of problems with them beacuse they were not cooled down as much as they should have been.

2 the rx8 on the dyno it has two oil coolers, a BIG radiator, and the intake.I personly dont think it had enough air cooling the oil coolers, the radiator, and air going into the intake.beacause in alot of post people r saying the car is freaking fast someone also compared it to the evo with the power delivery i donmt think he would have compared the two if the rx8 only had 220 crank HP and 184 rwhp.

Originally posted by eclps0
maybe the ecu is restraining power to protect the engine from over heating.

1 rx7s have overheated and alot of problems with them beacuse they were not cooled down as much as they should have been.

2 the yrx8 on the dyno it has two oil coolers a BIG radiator and the intake i personlay dont think it had enough air cooling the oil radiator and air going into the intake.beaqcuse in alot of post people r saying the car is freaking fast someone also compared it to the evo with the power delivery i donmt think he would have compared the two if the rx8 only had 220 crank HP and 184 rwhp

The 3rd gen RX-7's used to overheat because of teh heat that was retained in the engine bay. My FD withstood many a hard drive on a 110+ degree Texas day. The highest water temp I would get was 99C and that was after running fairly hard with only one oil cooler and just a Mazdacomp upgraded radiator. The R1's and R2's would be a few degrees lower with the second oil cooler. My 91' N/A RX-7 would usually only go up to 88C in the same temps.
With the better cooling of the RX-8's huge front openings and lack of heat retaining turbos I would have to guess the temps would be around the 88C range.

Originally posted by eclps0
maybe the ecu is restraining power to protect the engine from over heating.


If this were true, the runs would not yield consistent results.

I've read that the 8 can be shipped with two "types" of emissions equipement ... emissions equipment which conform to federal standards, and equipment which conforms to california standards (states other than cali implement cali standards).

... of the dyno runs published so far, what emissions spec was the car shipped with?

Here are the torque curves that Mazda has released so far :

http://us.f1.yahoofs.com/users/27decd74/bc/RX-8/__hr_torque_curves.jpg?BC3ZzN_ADNIzouwu


See how flat the curves are, that is the same shape that I have seen out of every properly running rotary I have ever seen/tested.


With the sharp fall off of torque seen in the graphs posted lately I'd have to say that there is definately a tuning issue or intake air flow here.

Hopefully someone who has dynoed their car or someone who is plannying on dynoing their car will read my previous post (just a few up the page) and get some definate answers to my questions. I have a feeling that with just a bit more info we can make some pretty good educated guesses.

I'm going to atempt to get my car on the dyno pretty soon and see how much data I can gather, but the more reference points we have the better.

One more thing I've noticed is that when cruising down the highway and then down shifting to say 4th I get a higher reading on the "Butt Dyno" than I get when starting from low RPM and running through the whole gear.

Reminds me of my previous RX-7 when the 6-ports weren't opening up properly.

how about doing a run with no air filter? that would solve the air restriction problem somewhat and we'll have prove to buy or not to buy K&N filters (or cold air intake) when it comes out

i work in torrance and would like to visit you when you do the next dyno

how about partially turn off dsc? instead of completely disable?

- Not being able to read from the OBDII port is unusual. There is a standard government mandated specificiation for OBDII interfaces (so that mechanics, emissions facilities, etc. can read them) and this car apparently didn't meet them. My scan tool is only 9 months old...

- Temperature was not a problem on the dyno. The car was cooled between runs and the power output was extremely consistent on each of the three runs we did. The hood was open and a 6000 CFM fan was used to blow air into the radiator opening.

- The mixture was taken from the tailpipe, no O2 sensors were removed. Readings are usually slightly leaner after the cat. As noted before, the mixture is rich, but not unusual for a high revving motor seeking to maintain OEM reliability goals. Other cars run richer, and the S2000 runs similar ratios too. Even leaning it out a couple of points is not going to generate the missing power. Additionally, the power before 6000 rpm was exactly as expected, even with the rich mixture.

- The car was a CA emissions spec car

If I was investigating this, I'd ignore the AF mixture and look at ignition timing above 6000 rpm - if you can find a way to read it without an OBDII scantool (may need a Mazda unit - if anyone from a SoCal Mazda dealer wants to bring one in with an RX8, I'm game).

SC

Just had a crazy idea, what if a dyno pull could be done with the auxilliary port injectors disconnected? Maybe that way the rich A/F mixture can be avoided at the top end. Of course I don't know if this can cause damage to the engine...

Originally posted by neit_jnf
Just had a crazy idea, what if a dyno pull could be done with the auxilliary port injectors disconnected? Maybe that way the rich A/F mixture can be avoided at the top end. Of course I don't know if this can cause damage to the engine...

Well, definitely this qualify as a crazy idea. I don't think anyone would want to do that to their car. We don't even know how the ECU is controlling the fuel and whether it will go into limp mode if injectors are detected to be missing. If not, you can do serious damage to the engine running at high rev without the needed fuel from that injectors. That's my random thought.

messing with the injectors?

that's just craaaaaa-zy!

Originally posted by ChurchAutoTest
-- The car was a CA emissions spec car


I know you probably can't get a fed spec car into your shop in California, but can anyone with a fed spec car that's been broken in get a dyno taken? I can't see the different emissions equipment accounting for the missing power, but it would be another datapoint and it could rule out another variable as the cause of the problem.

The other thing that would really bug me is that the ODB port isn't working ... it didn't think it was legal to sell a car these days that didn't conform to the ODB-II spec...

All US RX-8 are CA emissions compliant, there are no differences between CA or elsewhere 8's.

Originally posted by neit_jnf
All US RX-8 are CA emissions compliant, there are no differences between CA or elsewhere 8's. The warranty reports that budaman and FUBAR were pulling prior to delivery, suggest otherwise - some cars showed CA-spec while some showed US-spec under "Emissions".

i remember the other AFR's posted not getting super-rich (ie in the low 12's) untill after 6000 rpm, did you notice this Church?

or anyone else for that matter

reason i ask is because i remember the AFR's dropping rapidly as the rpms went to 6kish and beyond, pretty sure some other people pointed it out aswell

Check out the chart P00Man, it shows the AFR for the RX8. No real changes around 6k.

SC

I thought I bought a car with 247 bhp, and hoped it would put out at least 210(15% loss) at the wheels. I go to my friends shop today and what do I see? Freaking peaked at 174. I'm pretty pissed right now, I want a 1/4 of my money back, or a car that performs like it's supposed to. Mazda you better get your act together cus people are gonna start noticing you guys fucked up.

calm down, theres many threads on the boards cause of this already

the main concensus is that it is an ECU issue, due to the fact that the engines are running incredibly rich, and we know (thanks to the star mazda series) that the engines can put out the power

also, the engine isnt really broken in yet so that adds to it also, look around in the tech garage and check the sticky in discussion

im too stupid to read those charts lol

i dont know whats for the 8 and whats for whatever else was being run for comparo. think its an s2000 no?

edit:
ok, i see what you mean, but im pretty sure that the other charts showed different (either that or im halucinating) can anyone dig them up and post them here?

i dunno how to post anything like that, otherwise i would

If I was investigating this, I'd ignore the AF mixture and look at ignition timing above 6000 rpm - if you can find a way to read it without an OBDII scantool (may need a Mazda unit - if anyone from a SoCal Mazda dealer wants to bring one in with an RX8, I'm game).

If it is the ignition timing, that should be an easy fix, right? Totally controlled by the ECU. Do you think there is 20+ HP bottled up with that type of an issue?

If it is, the next question would be why. Would a radical timing adjustment be made to comply with emissions? I wish Mazda would start talking before lawsuits are taken.

Originally posted by P00Man
i remember the other AFR's posted not getting super-rich (ie in the low 12's) untill after 6000 rpm, did you notice this Church?

or anyone else for that matter

reason i ask is because i remember the AFR's dropping rapidly as the rpms went to 6kish and beyond, pretty sure some other people pointed it out aswell

I agree with church, it is normal to have 12.5 : 1 afr at WOT. I doubt Mazda would want it running leaner than 13 and even with that change you wont see 20 HP gains. Also, I am a little confused by the obsession with flywheel HP. The fact remains that what the car puts to the ground will determine it's performance and by the numbers it's putting out, it falls below it's competition. Sad to say but it just does not deliver the bang for the buck, atleast not yet anyway. I bet there is not much difference in performance numbers between the 4-port auto and the 6-port manual versions. Now if some of you could race the 2 versions and post the results.......

Lawsuits? LOL LOL LOL so funny ......

Originally posted by TurboSE
I bet there is not much difference in performance numbers between the 4-port auto and the 6-port manual versions. Now if some of you could race the 2 versions and post the results.......

Already done in Japan, 4 port "low power" 5MT vs 6 port "high power" 6MT... They got very similar numbers :eek:

Anyone knows the thread where they posted this?

Lawsuits? LOL LOL LOL so funny ......

Well, didn't Mazda have to anne up for the Miata fiasco. It may not have been brought to court, but it was embarassing to them to say the least. It hurts the image of Mazda.

Ignition timing is certainly capable of making a difference - far more than mixture does on a normally aspirated engine. Whether it will free up 20 hp or not is another story.

Modern engine control systems play a complex game of balancing ignition timing, knock and normal engine noise. On a rotary, playing this game fast and loose has more severe consequences than on a piston engine. Perhaps Mazda went extra conservative on knock sensitivity? Who knows, its really all speculation at this point - all we know is that something isn't right above 6000 rpm.

But, if its an ECU issue, I think it has something to do with ignition timing. I suppose the intake manifold system switches could be incorrectly hooked up (explaining the big dips when the runners open up), but that would seem to be less likely to me than an ECU reprogramming snafu - especially considering the work that went on in the ports and the OBDII issues.

SC

if this car is not running "that" rich im wondring why mine with only 250 miles that the tail pipes are allready very black with soot.im still beleaving its a combo of things,rich a/f,timing, etc.i also have not reved over 6000 and this soot is very,very black and has coated both tips very heavily and at only 250 miles. to qoute paul yaw, this thing is "pig rich".i think we need to call and e-mail mazda endlessly so we can get a ansewer. i will say this,i love this car,for me its the funest,quickest street car i have ever drove and it would be freakin awsome if we can get this 15/20 hp back.

Originally posted by ChurchAutoTest
Ignition timing is certainly capable of making a difference - far more than mixture does on a normally aspirated engine. Whether it will free up 20 hp or not is another story.

Modern engine control systems play a complex game of balancing ignition timing, knock and normal engine noise. On a rotary, playing this game fast and loose has more severe consequences than on a piston engine. Perhaps Mazda went extra conservative on knock sensitivity? Who knows, its really all speculation at this point - all we know is that something isn't right above 6000 rpm.

But, if its an ECU issue, I think it has something to do with ignition timing. I suppose the intake manifold system switches could be incorrectly hooked up (explaining the big dips when the runners open up), but that would seem to be less likely to me than an ECU reprogramming snafu - especially considering the work that went on in the ports and the OBDII issues.

SC

Good to see you here UL.

RedS2.

From the tailpipe description it looks to be running very rich. For comparison sakes, the Prelude engine is desined to run rich, especially when in VTEC. Many club members reported much less black soot after installing a VAFC and leaning out the mixture on a dyno.

Perhaps the below pictures can show the problem a little bit better. I took the Mazda released RX-8 hp and torque curves, subtracted 17% for all values and graphed them. I then pasted the hp and torque curves over the dyno results from SC.

It appears that the dyno hp and torque curves are very close to or a little bit higher than the (claimed - 17%) UNTIL 6250 rpm. Of course we are all aware what happens at 6250 rpms yes? A problem with the auxiliary port or FAD may or may not be part of the problem but that hp curve does look pretty smooth until 6250.

Realize that the missing hp should instead be described as the missing torque at high rpms. It apears that around 11 ft-lbs are missing at 8500 rpms and about 19 ft-lbs are missing at around 8900 rpms.

With patience, the answer will eventually reveal itself.

Brian

Buger's graphs are back! Good stuff as always. Thanks - I almost understand what is happening now.

Have Mazda optimised the ECU to give Joe Bloggs (and maybe even the press) more torque lower down at the expense of those of us who like to rev the car? Maybe even trying to optimise the 0 to 62 mph?!?!?!

Originally posted by akrx8
if this car is not running "that" rich im wondring why mine with only 250 miles that the tail pipes are allready very black with soot.im still beleaving its a combo of things,rich a/f,timing, etc.i also have not reved over 6000 and this soot is very,very black and has coated both tips very heavily and at only 250 miles. to qoute paul yaw, this thing is "pig rich".i think we need to call and e-mail mazda endlessly so we can get a ansewer. i will say this,i love this car,for me its the funest,quickest street car i have ever drove and it would be freakin awsome if we can get this 15/20 hp back.

First of all, it is a rotary. If you have seen other rotaries you know you will get sooty tailpipes. Also timing retard can result in incomplete combustion causing poor mileage and soot build-up.

That latest dynopack runs look a lot like the 89 NA motor I put in my 84 RX-7. The variable dynamic intake(VDI for short) valve was stuck closed. The 89 had a less complex but similar variable length/configuration intake. Right at 6,250rpm my dyno plot and AF's went screwy and it just wouldn't make any more power. No matter how much I fiddled with the timing & fuel- I was running an SDS programable EFI system- we couldn't get any more power over 6,250 rpm. When we discovered the sticking valve power shot up 20+hp. just seems the RX-8 is acting strangely similar to me.

I don't have any plots of this since it was during tuning and not the final "product".

For those wondering what kind of times the production cars are turning out, the latest issue of Australia's "Motor" mag turned out the following times:

0-100km/h
* RX-8 6.99
* 350Z 6.45
0-400m (1/4mile)
* rx-8 15.12@151.8km/h
* 350Z 14.49@161.4km/h

I thought the Z was 5.4 seconds?

No two mags are the same. Australian mags test the cars side-by-side on a race track, with a tank of fuel. Both cars were lined up at Calder park with the 350Z (a touring here) getting the same times as Wheels mag did last month. What important is that Wheels rattled of a 6.4 0-100 and 14.8 1/4mile for the RX-8 from what looked to be a pre-pro car. In other words the Z's consistent times seems to indicate that the rx-8 tested by Motor was noticeably slower than that tested by Motor. Both mags use a Corevvit.

-pete

What is the hp rating on that car? 247 hp? If so then there is a problem. There is no way a 3000lb car with 247 hp should be pulling off 15.1 1/4 mile times which is the same "magazine" 1/4 mile time as my 2950lb, 200hp Prelude. Let's hope Mazda can fix this quick. :)

Originally posted by wakeech

um, dude, i think you're thinking of kW (which is closer to 1.3hp/kW).

a ps is about 0.93hp IIRC

Lets clear this one up:-

1 BHP (SAE) = *1.01387 BHP (PS) = 0.7457 KW

For all practical purposes this is not a concideration... EG, the RX8 is quoted at 247BHP (SAE), or 250PS.

im wondring why we havent got any info from mazda yet,i found on the aussie forum lock&load wrote a letter to there guy and received the replie within a few days.looks like only the us cars have the problem and havent seen a post from rotary news in quite a few days. i still love this car and seems fast but i really just want to know, wether its good or bad.just spill the beans mazda.

What are the expert opinions about this?

Originally posted by Lensman
What are the expert opinions about this?
http://www.rx8forum.com/attachment.php?s=&postid=96933


Yeah, but that's isn't what's happening here.

That tip refers to what the BMW M3 does for example. It will completely cut fuel at a lower than maximum RPM. So you can't go past a certain RPM at all until the coolant reaches a certain temperature. In essence, your new redline is at 7000RPM until the engine warms up and then it begins to gradually rise until the engine is at optimal operating temperature.

The RX-8 will still go all the way to 9000RPM and even a bit past. It's just not making the expected power.

Just a thought...

You're missing, what... 20Bhp?

The European ECU is missing 20Bhp due to the more strict Euro4 emissions regs... perhaps you have been given this ECU by accident... 228Bhp apparently... BUT I hope that isn't the case, because the plot shows somthing wrong, not just lower output.... It'd be really bad if this was the plot from the Euro ECU.. .

I very much doubt its the Euro ECU. Running ritch wont help the car pass Euro4 emmisions now will it?

Also our cars have been delayed until november because of the new emisions settings.

Originally posted by RomanoM


Yeah, but that's isn't what's happening here.

That tip refers to what the BMW M3 does for example. It will completely cut fuel at a lower than maximum RPM. So you can't go past a certain RPM at all until the coolant reaches a certain temperature. In essence, your new redline is at 7000RPM until the engine warms up and then it begins to gradually rise until the engine is at optimal operating temperature.

The RX-8 will still go all the way to 9000RPM and even a bit past. It's just not making the expected power. Just because that's the way the M3 ECU does it, doesn't mean that that's the way the RX8 ECU will do it.

---jps

Originally posted by BlueAdept
Just a thought...

You're missing, what... 20Bhp?

The European ECU is missing 20Bhp due to the more strict Euro4 emissions regs... perhaps you have been given this ECU by accident... 228Bhp apparently... BUT I hope that isn't the case, because the plot shows somthing wrong, not just lower output.... It'd be really bad if this was the plot from the Euro ECU.. .
I doubt they'd fit the wrong code by accident. But it could be that they had difficulty meeting the US emissions spec and had to do the same kind of thing that they have done with the Euro ECU so it ends up being very similar. Note that the peak power is now at around 8200 not 8500, same as Euro spec. I'm not sure it looks wrong, it just looks like they have absolutely killed the top end, which I fear is exactly what they have done to the Euro spec cars too.

There has been speculation that they programmed all the ECU's while they were in port. This almost certainly means they were still working on the ECU code right up until the last minute (they finished writing it while the cars were being shipped). They already had working code in the Japanese production cars, so why all the last minute changes? US emissions is the only thing I can think of, they must have had difficulty simultaneously satisfying power and emissions requirements. Maybe they even held back the cars in port for another week or so while they tried to find a way of achieving this. Unfortunately, it looks like they didn't succeed.

Originally posted by ChrisW
Unfortunately, it looks like they didn't succeed.

Well then they would deserve the fiercest criticism because it's not like they didn't know in advance what the US emission requirements were. If they advertised an engine at a specific output in the US without first establishing if it was possible then they are stupid. This is of course hypothetical but it's about time we knew the truth (Statements of great obviousness # 2345.1)

Originally posted by Lensman
If they advertised an engine at a specific output in the US without first establishing if it was possible then they are stupid.
Didn't they do exactly this with the Euro spec cars, telling us it would be 240 ps before they had established whether this was possible or not? I'd like to think Mazda aren't stupid, but the longer this goes on, the more it looks like the most credible explanation ("when you have eliminated the impossible, what remains, however improbable..." etc).

There is a difference between "expected" and "final". When they advertised 250 in the US, it was expected HP. When they got the final numbers, it was 247. So that's what was advertised.

Originally posted by ChrisW

Didn't they do exactly this with the Euro spec cars, telling us it would be 240 ps before they had established whether this was possible or not? I'd like to think Mazda aren't stupid, but the longer this goes on, the more it looks like the most credible explanation ("when you have eliminated the impossible, what remains, however improbable..." etc).

This is slightly different: the 240bhp car that we were promised met current regulations and they could have gone with it. The car we'll get will meet projected requirements and they presumably decided to do this late in the day.

Have they still made no responses on this? I would think that by this time they would have. I see more and more RX-8s on the road, I wonder how many went in to buy one before doing the research. Hopefully none. When I bought mine I knew what I was getting into. I am just hoping Mazda does the right thing and owns up to it, and fixes it.

Originally posted by KamokuWan
Have they still made no responses on this? I would think that by this time they would have.

I don't know, It's only been what, 2 weeks since the first dyno came up? Give them a few days to hear about it, I don't think 1.5 weeks is that "long" of a time for a corporation like mazda to take to research and formulate a response for something like this...

Originally posted by akrx8
........and havent seen a post from rotary news in quite a few days.........

Guys:
You haven't heard from us in a few days because there is really no new concrete information to report on yet. We've been talking to a lot of folks and shaking some bushes, but no definite answer has been established yet. Dan is breaking-in the RN RX-8 and as soon as it's ready to go, we will be putting the car on the dyno and doing some research. Also, major import magazines have caught wind of this issue, and have already or are going to very soon, commence their own dyno testing. Should be interesting!

Anyway, from the little and scarce information we've been able to gather, it's unfortunately looking like an emmisions equipment issue. This of course is all unconfirmed and speculative still.

STAY TUNED!

-Bern

WOOHOO thanks Bern.. power to the people!

Aw man, if the mags caught wind of this, you know it had to be from here.. Information is contagious..

...you know it had to be from here.....

It might've been, but at least one magazine contributor tested a car he had available, and was baffled by the #'s. He started to looking for answers, immediately. This was at least a couple weeks ago, and no real mention of the forum or it's information was cited.

BTW, a few tuners around the country now have 8's in hand, and are starting to conduct dyno test.


Again, shoud be interesting...

-Bern

...and soon the whole world will know. Or at least those that read car mags, with ripples spreading ever outward. I wonder if it will ever make the TV news on a slow day: Mazda 'cheating' buyers by inflating HP estimates yet again (or something similar). Mazda better pray their PR people make a response (ANY response) before that happens.

I love my car but I am very concerned about Mazda's reputation and the effect on future rotary vehicles ever being approved by Ford for release. It's been three weeks since the first dyno graph here from 1stRX8 and over 2 weeks since Compaddicts dyno with all environmental conditions was posted. Tick tock.

Originally posted by bern


Guys:
You haven't heard from us in a few days because there is really no new concrete information to report on yet. We've been talking to a lot of folks and shaking some bushes, but no definite answer has been established yet. Dan is breaking-in the RN RX-8 and as soon as it's ready to go, we will be putting the car on the dyno and doing some research. Also, major import magazines have caught wind of this issue, and have already or are going to very soon, commence their own dyno testing. Should be interesting!

Anyway, from the little and scarce information we've been able to gather, it's unfortunately looking like an emmisions equipment issue. This of course is all unconfirmed and speculative still.

STAY TUNED!

-Bern

Check out the K&N thread. If what is reported is true and 16hp was found with a "filter charger" or the like, then that should give us an idea re A/F ratio and or timing.
http://www.rx8forum.com/showthread.php?s=&threadid=8903

:D

Everyone's pointing towards the ECU as being the source - I have a simple question for those in the know - is it possible? I mean does it make sense that an ECU could free up an additonal 20+ Hp?

I believe Mazda knows already. It is highly improbable that they are unfamiliar with their engine. The ECU question could be answered immediately (on remapping) and at this point I would venture to say that the only reason that there is a form letter response is that they are deciding what their options are. I wrote them and received a reword statement of my own with the same reply - we are looking into it.

Originally posted by pelucidor
It's been three weeks since the first dyno graph here from 1stRX8 and over 2 weeks since Compaddicts dyno with all environmental conditions was posted. Tick tock. Step back and take a breath of reality for a moment.

Mazda is a large company. If you've ever dealt with a large company like Mazda (or Ford, or GM) you know that it would take two or more months for the company to approve a statement for release saying the sky is blue.

I'm sure Mazda is investigating and is preparing a response, but even when they do know something it will likely take awhile to make its way through legal.

In the mean time, don't forget that those of us here, along with those who read car magazines in general are an infinitesimal portion of the market and at best represent perhaps 5% of buyers or potential buyers...

Originally posted by Lensman


This is slightly different: the 240bhp car that we were promised met current regulations and they could have gone with it. The car we'll get will meet projected requirements and they presumably decided to do this late in the day.
I don't believe thats true. Do you have any old literature saying that the car produces 240 ps and meets Euro 3? I thought it was supposed to be Euro 4 all along. Anyway, did a 240 ps car meeting any Euro regulations ever exist? Does a 231 ps car exist? My understanding is that these are just expected figures (pre-production cars don't have to meet emission regulations so they are not representative). Given that they can reprogram the cars when they arrive at their destination, it's even possible that they are still working on getting 231 ps for the Eurp spec cars.

I think/believe the Australian car , as they have ~ Euro stage 3 emmissions is the 240ps version.

If so that car would be legal for sale in Europe now. but not in 1.5 years time.

Yes, but is the Australian car actually on sale yet, or is this just another spec that Mazda hope to meet. Or if it is on sale, does it really produce 240 ps?

Australians are driving tgheir cars right now.

No reports of missing power , but no dyno's Ithink.


They are looking at ways to get from 240 to 250 ps tho :)

So I have been following this whole hp thread. The 6MTs are making 180hp or so at the rear wheels. From the dyno charts, power does not seem to increase as it should above 6,000rpm and the shape of the curve gets all lumpy.

Buger scales the Mazda power graph and overlays it with a production dyno graph. Power looks to be kosher until just past 6,000 rpm.

So...last night I get the R&T RX8 supplement in the mail and am reading over it. Numerous times it refers to 250 or 247 hp. It also shows 147mph at 9,000rpm in 5th gear and 148mph at 7650? rpm in 6th gear with an asterisk. The aterisk denotes that it is speed limited electronically. Also, in the engine section it shows that the additional intake port is supposed to open at 6,250 rpm.

My point is that since the performance of the 250ps and 210ps car seem to be so close (Japanese magazine published data), doesnt it seem logical that there is a problem with the additional intake port opening at 6,250rpm? Combine this with the story above the preproduction cars having a problem with a sticking port?

I am not a car mechanic, but I do build two stroke motorcycle racing engines and alot of the port issues with the rotary are very similar in concept. I just looks like the car runs fine until just over 6,000rpm, so why dont you break down the things that can only occur at that point?

Thanks,

Rocky
6MT Titanium/Black/Grand Touring

The Graphs clearly show the Port opening above 6000 RPM.

The graphs clearly show a dip above 6,000. Even in Buger's post he made a correlation between the fact that the graph seems to encounter problems at the same RPM that the port is supposed to open. Youre assuming that because there is a dip at 6,250 that the port is functioning correctly. I simply see a dip and then the power curve is rough and the horsepower does not build as it is claimed to do past this point. What's your idea?

Thanks,

Rocky
6MT Titanium/Black/Grand Touring

I haven't been able to figure out, what was the drive train loss for the generation 3 NA RX-7? or the other generation RX-7's? this would be a good point of reference, as the engine isn't radically different and the drain train for the 8 should be quite effeicent witha carbon fiber drive shaft.

Originally posted by twocycler
The graphs clearly show a dip above 6,000. Even in Buger's post he made a correlation between the fact that the graph seems to encounter problems at the same RPM that the port is supposed to open. Youre assuming that because there is a dip at 6,250 that the port is functioning correctly. I simply see a dip and then the power curve is rough and the horsepower does not build as it is claimed to do past this point. What's your idea?

Thanks,

Rocky
6MT Titanium/Black/Grand Touring



I agree. What if it were an airflow problem or obstruction... you would see a dip with port-opening turbulence or whatever, but w/o resonance induction you won't see full power.

Does anyone know what power a baseline NA rotary would make w/ non-resonating intake flow at that rpm?

one more thing... this next point is painfully non-technical but note that the difference between Acura TL (225hp) and TL type S or type R or whatever has 260hp is purely a high rpm resonance in the intake

Originally posted by ProtoConVert
one more thing... this next point is painfully non-technical but note that the difference between Acura TL (225hp) and TL type S or type R or whatever has 260hp is purely a high rpm resonance in the intake

But don't forget that the TL-S also has a freer flowing exhaust, larger throttle body, higher compression ratio, higher redline, more aggressive cams, and different intake valves.

(sits quietly in corner)

Those would indeed account for a good part of the power. In fact now that I look at it more it seems the intake difference on the type S is more of a ram air effect than resonance.

Originally posted by BillK
In the mean time, don't forget that those of us here, along with those who read car magazines in general are an infinitesimal portion of the market and at best represent perhaps 5% of buyers or potential buyers... Imagine a TV news exec who reads car magazines, sees this story in several of them a month or two from now and decides to push it on a slow news day to 'protect' their viewers from Mazda's repeated false advertising (remember the Miata).

Do you remember the totally false 'unintended low-speed acceleration' story that singlehandedly and overnight almost killed Audi in the USA for many years? It eventually (years later) turned out to be people hitting the gas instead of the brake pedal and blaming Audi for the resulting low speed crunch into their garage wall. Look at the damage that can be done by an untrue story if it gets on TV...

Originally posted by pelucidor
Do you remember the totally false 'unintended low-speed acceleration' story that singlehandedly and overnight almost killed Audi in the USA for many years?Oh yeah. Watching from Down Under, it was blatantly obvious right from the outset that morons were simply hitting the wrong pedal. We watched with growing amazement and a sense of "Only in America" as it got as far as it did.

Originally posted by pelucidor
Imagine a TV news exec who reads car magazines, sees this story in several of them a month or two from now and decides to push it on a slow news day to 'protect' their viewers from Mazda's repeated false advertising (remember the Miata).
Now imagine the same news exec in the general manager's office being told they will not, repeat not endanger automotive advertising revenue and thus the story is spiked...

Originally posted by eccles
Oh yeah. Watching from Down Under, it was blatantly obvious right from the outset that morons were simply hitting the wrong pedal. We watched with growing amazement and a sense of "Only in America" as it got as far as it did.

Actually, funny you say that. My uncle had an Audi with electronic throttle. He was sitting at the lights one day when something went very wrong and the throttle stuck wide open. He said he stupidly didnt think the shut the car off as it torched it's tyres through a red light narrowly missing traffic.

As for the OZ-spec 8's. Yep it's Euro3 compliant. Australia is slowly converting to ECE compliance, thus all power figures are quoted as ECE and cars have to meet Euro 3 by 2004. Mazda complianced the RX-8 as an 04 compliant car, thus they will not have to recomply it here next year Unlike, for example, nissan. Australia is slowly shifting away from US-style emissions requirements.

On this subject though, does anyone think it's odd that California got 250ps cars? They have emissions standards that would surely leave Euro3 well behind yet they got Japanese power levels!! Despite the fact that they are getting the same maps as the most generous country in the world in terms of emissions. It just doesnt line up.

Let's say for a moment that Cali emissions requirements were somewhere between Euro3 and Euro4/5 (which I thought they were). Experience tells us that power is inversely proportional to tailpipe standards. Thus you would expect power to be no more than about 235 probably closer to 230. That would then line up perfectly with the RWHP numbers people are seeing wouldnt it?

So my theory is that everyone in the US is geting Cal. spec cars and hence less power. Well, it's just a theory anyway :)

-pete

The graphs might have shown the auxilliary ports opening at 6000 rpm but that does not mean that the port sleeves rotated all the way to open the port fully. It could be partially open causing airflow problems. Ok, having spoken to someone at the local dealer I am convinced there is no such thing as a mileage switch or some sort of ecu chip replacement at a service interval. He said his service tech trained by mazda would have known for sure.

The problem with that theory is simply they already did that when they reworked the Miata engine a couple of years ago. I can't imagine they would make the EXACT same mistake AGAIN causing them to offer the same options as they did with the Miata owners.

I've read a couple of posters who say they feel the car losing steam around 7500 rpm. I went to a nice deserted track this evening and played around with the red line in 1, 2 and 3 gear. I must say that i can't feel any power loss 1 and 2. Red lining 3 takes some effort (=length of track;)) but the air friction building up at speed^2 explains that I guess.

I don't doubt that the dyno's get the values they are in the fixture, however if the HP curve went flat after 7500rpm, wouldn't that be quite noticable to a driver (with friction building up square)? What does your butt-dyno tell you?

/Elak

Originally posted by Elak
I don't doubt that the dyno's get the values they are in the fixture, however if the HP curve went flat after 7500rpm, wouldn't that be quite noticable to a driver (with friction building up square)? What does your butt-dyno tell you?

/Elak

Hercules has stated elsewhere that he feels his engine isn't performing as expected above 6250rpm.

Been watching this thread for a while now. I did the recommended break in on my car, not above 6,000 till 600 miles. Then I added my own break in, not above 7,000 till 1,500 miles. After this only short trips up to the top. I have already done two oil changes on the car. Not that it needed it, but I figured if they recommend a 600 mile break in, it would not hurt to change the oil at 600 miles. the second was more to put it at an even number for easy reference as to when the 2,000 mile oil changes are going to be due.
Now that the car is over 2,000 miles, I decided to check out how the power delivery felt as it accelerated through its upper end. I ran the car in 2nd and 3rd up to 9,000 rpm and I have to say I did not feel the loss in power. I felt the car building power all the way up to around 8,500. I had a passenger in the car who verified my findings.
I think it is time for me to find a Dyno and see what this thing is putting to the ground.
Anyone know of one in the East Bay area of San Francisco. I am just North of Berkeley. I need to find one anyway so I can start tuning my RX7 when I finally get it back from the shop.

I too have been experimenting with red line, primarily in second. I havr the same conclusion as Hecules. At or about 6200 RPM there is a hesitation, and then just linear response to additional RPM's. This is not 40 additional HP kicking in, as was noted in some magazines who tested high power cars that were working properly.

I believe that as a group of owners we need to all work together to try and pinpoint where the loss of power is or the flat line response starts. We should all feel something more than a hesitation at the 6200 to 6300 RPM transition. if this is where we all can conclude we don't feel boost then there is really only one explanation, third port mechanically or electronically failing to operate correctly.

I am not in favor of letting my local Mazda dealer machanic take my car out and repeatedly red line it to come back and say it feels okay. They probably have less knowledge of what to expect from this car than we do.

As a group we need to go out and perform open road red line test, paying extreme attention to RPM and engine feedback. My best results is to linger in second at about 5500 RPM, and then when I get the chance accelerate while monitoring RPM in conjunction with engine noise and feel. You will have to turn off your stereo and A/C for best results.

We need to post our observations and results back to a single thread for compilation. Then we as a group need to find a way to get heard by Mazda Corporation and not a lot of individual dealerships. It is my experience that dealers and their mechanics with this type problem are institutionally indoctrinated to not recognize or in any way sympathize with the customer over optimum performance issues.

I believe the most unbiased and independent info we have so far are the dyno's, poor track times adds the worst variable of all, the driver. This car is performing, and I think that a lot of the owners who have now driven it more than a thousand miles know, it is not performing as advertised above 6250. There was an advertised kick (mock super charger affect) (40 additional HP kicking in between 6250 and 8500 RPM) at this point I just don't feel or hear it happenning. Just my thought on this subject. Individually I feel we don't have a chance, but as a group I think we can get to the bottom of it.

Originally posted by RX8-U-UP
I too have been experimenting with red line, primarily in second. I havr the same conclusion as Hecules. At or about 6200 RPM there is a hesitation, and then just linear response to additional RPM's. This is not 40 additional HP kicking in, as was noted in some magazines who tested high power cars that were working properly.

I believe that as a group of owners we need to all work together to try and pinpoint where the loss of power is or the flat line response starts. We should all feel something more than a hesitation at the 6200 to 6300 RPM transition. if this is where we all can conclude we don't feel boost then there is really only one explanation, third port mechanically or electronically failing to operate correctly.

I am not in favor of letting my local Mazda dealer machanic take my car out and repeatedly red line it to come back and say it feels okay. They probably have less knowledge of what to expect from this car than we do.

As a group we need to go out and perform open road red line test, paying extreme attention to RPM and engine feedback. My best results is to linger in second at about 5500 RPM, and then when I get the chance accelerate while monitoring RPM in conjunction with engine noise and feel. You will have to turn off your stereo and A/C for best results.

We need to post our observations and results back to a single thread for compilation. Then we as a group need to find a way to get heard by Mazda Corporation and not a lot of individual dealerships. It is my experience that dealers and their mechanics with this type problem are institutionally indoctrinated to not recognize or in any way sympathize with the customer over optimum performance issues.

I believe the most unbiased and independent info we have so far are the dyno's, poor track times adds the worst variable of all, the driver. This car is performing, and I think that a lot of the owners who have now driven it more than a thousand miles know, it is not performing as advertised above 6250. There was an advertised kick (mock super charger affect) (40 additional HP kicking in between 6250 and 8500 RPM) at this point I just don't feel or hear it happenning. Just my thought on this subject. Individually I feel we don't have a chance, but as a group I think we can get to the bottom of it.

Excellent post!

Originally posted by RX8-U-UP
I too have been experimenting with red line, primarily in second. I havr the same conclusion as Hecules. At or about 6200 RPM there is a hesitation, and then just linear response to additional RPM's. This is not 40 additional HP kicking in, as was noted in some magazines who tested high power cars that were working properly.
<snip>

There was an advertised kick (mock super charger affect) (40 additional HP kicking in between 6250 and 8500 RPM)
<snip>


Ok, the hesitation at 6250 is consistent with the dyno's, however between 6500 and 7250rpm the graphs show nice linear build-up of power (15-25bhp) .

Judging from your text you agree with this sensation, however what you expected was a 40bhp turbo-kick? I've eagerly awaited this car for 3 years, and believe I've read quite a few reviews and descriptions, however I can't remember anyone describing a turbo-kick. If the turbo-effect is more that of a low preassure turbo, then a linear buildup of power should be expected, right?

If all those 40bhp came around 6500rpm (at 165-170bhp according to dynos) then you would already have reached the peak power, way before 8500rpm.

The dynos get what they get, but is the people reporting lack of power mainly a question of expecting a high preassure turbo-kick and not getting it?

/Elak

Elak, Your point is well taken, but I was in no way expecting a turbo type response. There appears to be nothing more than increased RPM = increased speed (with a gurgle at 6200, like it thought about doing something). I did and do expect a boost of power since developing 40 additional HP in 2000 RPM should and would provide this expectation. It was descibed as a mock super charger effect, in this 2000 RPM band. The loss at the rear wheels should be across the whole spectrum, not all in its optimum power range. Don't get me wrong, I love what I got. I just feel we were promised more, and others have gotten more from this car in testing.

Just took my car out again and did several runs 1st gear and 2nd gear. I think I can feel the hesitation you are talking about but I only noticed it if I did not have the throttle pinned. Although I did not notice the hesitation when smashing the gas pedal, I did notice is that right around 7,250 I felt and additional rush of power, not only felt but heard. Windows down, it sounded like a little mini turbo rush. I started rolling in 1st at 5,000 rpm and just floored it, 1st and second. DSC and Traction control off, AC and Stereo off.

I am still looking for a shop with a Dyno where I can do tuning on my FD, and I still want to run my 8 so I know for sure what is going on with it. My FD until this year has always been stock, so I have had no need for tuning. I will check over in one of the forums specifically for RX-7's and see if anyone knows where to go in the Berkeley, San Francisco area.

Ok, so if we stay with the sensation of acceleration, what are you expecting? If not a turbo-kick, were you expecting to be further pushed down in the seat (acceleration increase) above 6500rpm?

With air-friction building up square (I believe it becomes the main friction component at 25-35mph), I'm not sure you can expect to feel acceleration increase except in 1'st gear. In 2'nd you are already at 40-60mph at the relevant rpms, and achieving maintained acceleration (keeping the butt preassure up) seems to me to be more in line with a linear power build-up.

In my subjective opinion this car is much more powerful than my previous (210bhp) car, so unless it too was over-speced, I'd say the RX-8 I'm driving has more than 210bhp.

/Elak

"poor track times " rx8-u


i recall someone posting about a "freind" or what have you getting a 14.9 at the 1/4 mile strip, he also said that his freind has the time slip to prove it, perhaps we could ask him to scan the strip and post it, cause i really dont think a car putting out 180-190 hp to the ground could get such a time

That is what is so deceptive about this problem or the perception of a problem. At 210 HP the new Low Power Renisis 13B rotary is more powerful than any other N/A 13B rotary that has been produced. From the original and each succesive generation of RX7 N/A rotaries we found and came to accept that a low power and low torque small engine can still produce speed, pick up and intense exhilaration while driving. This makes it very hard to objectively evaluate an N/A rotary that produces 247 HP. With my limited experience with rotary powered vehicles, I believe that a rotary producing 210 HP would feel and give the perception in every way as being faster and more powerful than a 210 HP piston driven engine to the driver. Objectivity is tough, when there are no comparisons for the new renesis rotary. I respect your tempering of my sometimes slanted posts. Got to go driving. Zoom, Zoom.

I know the technical validity of this is probably squat, but acording to my dealer (whom I just went to see) the engine produces 247HP without all the extra crap of belts, AC, alternator, etc.

I said I thought he was full of caca, and he promised to ask Mazda about it, but I dont think he will. I'm still waiting for oficial word from Mazda to be honest, but thought I'd post a bogus opinion anyways :D

Originally posted by Genom
I know the technical validity of this is probably squat, but acording to my dealer (whom I just went to see) the engine produces 247HP without all the extra crap of belts, AC, alternator, etc.

I said I thought he was full of caca, and he promised to ask Mazda about it, but I dont think he will. I'm still waiting for oficial word from Mazda to be honest, but thought I'd post a bogus opinion anyways :D

Even if it is true then it's true for all cars and the dyno measurements for other cars are as expected whereas those for the RX-8 are not.

Sorry RX8-U-UP,

I hope your not getting annoyed with me, but I'm just genuinly interested in the discrepancy I sense between what is registered on the dynos, and what I experience when accelerating my RX-8.

Since you and Hercules have a different perception of the acceleration sensation, I'd like to know as much as possible about about your experience and also what you expected (may look like I'm trying to corner you but this is curiosity;)).

Btw I do have the high power engine and my previous reference to my old 210bhp, is just in reference to the current dyno indication that the high power engine only produces ~210bhp on the flywheel.

Simply put, my observations are:

#1 I can't feel the power curve of my engine flatten out around 7200rpm as the dynos suggest.

#2 Compared to my previous experience of 210bhp piston engined car I'd say the RX-8 is more powerful.

As a single observer I understand this has little relevance, however if more drivers come to the same conclusion, then that may be circumstantial evidence that the dyno-sessions are missing some parameter in their setup. It doesn't say anything about what the actual power is, only that it doesn't behave like on the dyno.

/Elak

Couple of comments:

1. Unless you are a professional racer of some renown, your butt is probably quite inaccurate. Human beings are quite good at resolving changes in acceleration (known as 'jerk'), but very poor at resolving actual acceleration levels. And on the street, there are constantly little changes in acceleration taking place due to bumps, shifts, etc. that can confuse your butt. We're very fond of saying that "The butt dyno lies". I just had a racer the other night tell me that his car felt slower, yet he turned his fastest lap of the night in that "slower" car.

2. The hp still peaks above 8000 rpm on the RX-8s. Its just that the torque curve falls off much faster than it should for a 247 hp car. There should just be _more_ under the curve than what we're seeing.

3. Instead of using the butt dyno to attempt to feel what happens on the street, why not instrument the car? At a minimum, use a G-tech. For those in SoCal, drop me a line and you can stop by the shop and use my Vericom which continuously monitors G-force during acceleration. You can see just how much acceleration falls off after 6000 rpm instead of guessing.

SC

I'm sure you'll get takers on that offer. Sadly I'm in northern CA:(.

I couldn't agree with you more on the absolute acceleration inaccuracy, however I'm arguing that you would have an acceleration decrease above 7200rpm if the dynos show the whole truth. Both dyno's I've seen on this board are pretty much flat power after 7700rpm (after a dip around 7200rpm). True - one displays a peak of 5bhp just around 8500rpm, but it is flat before and after. Constant power with friction increasing as rpm^2 (assuming same gear) should result in an acceleration decrease.

Enough to notice with the butt? Can be questioned, and you're quite right I'm no race driver. Anyway be sure to post results from whomever is the lucky taker of the accelerometer.

/Elak

Sports Car International May 2003 outlines the process: “ A mock supercharging effect derives from the sequential operation of the three intake ports on the high power version. Each port primary, secondary and auxiliary-come into play at a different stage of the induction cycle. The secondary opens at 3,750 rpm, the auxiliary port at 6,250 rpm. A variable valve in the intake tract opens a straight induction path into the auxiliary port at 7,250 rpm. Engine timing changes with each induction stage, so that breathing recalibrations are seamless to the driver. This motor lives to spin at 8,500 rpm.” This implies to me the continuous building of power to the 8500 rpm point. What does this mean in respect to the dyno charts that are currently on file? Are we seeing all of these milestones on the graph? Just a few questions, since we have the dyno experts on the thread.

Originally posted by Genom
I know the technical validity of this is probably squat, but acording to my dealer (whom I just went to see) the engine produces 247HP without all the extra crap of belts, AC, alternator, etc.

I said I thought he was full of caca, and he promised to ask Mazda about it, but I dont think he will. I'm still waiting for oficial word from Mazda to be honest, but thought I'd post a bogus opinion anyways :D

Your dealer would be incorrect. SAE NET horsepower (what the RX-8 HP is quoted in) is measured with the items connected that are required to run the engine such as alternator, water pump, belts, exhaust system, etc. A/C is probably not included but that's about it.

The old "SAE GROSS" horsepower that is typically quoted for cars that were measured pre-1972 did not have all of that stuff attached. That's why they typically had higher horsepower ratings for the "same" engine

Here's more info if you'd like

http://neptune.spacebears.com/opine/horsepwr.html

Hey, I told ya I thought he was full of doodoo. Didnt beleive a word of it myself since it would be VERY misleading and stupid to do something like that. Just thought I'd add a dealer story to the pile while we wait for a real reply.

Remember, what you feel when you are accelerating is proportional to the _torque_ curve. HP is a better measure of overall accelerative ability because it allows us to account for gearing, but the acceleration curve, in g's, will follow the torque curve precisely for any given gear.

In fact, allow me to make a prediction for anyone choosing to use an accelerometer on a stock car. This prediction assumes that the dyno curves represent how the car performs in the real world. It also assumes a 150 lbs driver, full tank of gas and average conditions near sea level. Variances can change the absolute levels, but not the _relative_ acceleration.

1. You will see peak acceleration between 5500 and 6000 rpm. In 2nd gear it will be approximately 0.45 G.

2. By 8000 rpm the acceleration curve will drop off to approximately 0.37 G and will keep dropping after that point at about the same rate (0.04 G per thousand rpm). In other words, the acceleration will drop off about 10% per thousand rpm above 6000 rpm.

3. In 3rd gear, the peak acceleration rate will be approximately 0.32 G. Above that point the acceleration rate will drop a little faster than in 2nd gear thanks to aero effects.

Now, in 2nd gear, the rate of change of rpms will be about 1000 rpm/second. Trying to resolve a change in acceleration of 0.04 G/sec is pretty darn tough. So let's think about 3rd gear. The rate of change will be closer to 600 rpm/second. But now the change in acceleration will only be 0.015 G/second. Again, very tough for the human butt to resolve :)

If the results are not similar to what I've predicted, then maybe something is different between dyno runs and the real world. We'll see.

SC

Well, I doubt my ass is calibrated that fine, but I'll give it a shot tomorrow :D

CAT,

I assume your calculations are correct, however I'm not sure you can ignore the air friction at high rpm in even 2'nd gear. I would suggest doing all tests in first gear to minimize that effect.

A change from .45g to .37g over a few seconds would be quite noticable. It is equivalent to your 150 pound driver losing 12 pounds of weight over the same time in the earths gravity field (Atkin's eat my shorts;)), however absolute values will be hard to "feel".

Now what would we expect if Mazda is right, and the dynos "wrong"? Mazda's published torque curve is flat as a pancake between 6000 and 8000 rpm. If we assume we can ignore the friction buildup, the acceleration should be pretty much constant over that rpm range.

I'll try to find an accelerometer at work...

/Elak

Air drag at 60 mph is equivalent to about 0.1 psi of positive pressure acting on the surface of the car. That pressure is acting on a CdA on the RX8 of about 720 inches. That equates to about 70 lbs of drag. Compared to the 1400 lbs of thrust or so the RX8 produces in 2nd gear, you're talking about a couple of percent. And the pressure at 40 mph will be about half that, so the relative difference would be about 30 lbs of drag or 2% between those two speeds. If you do the test in first gear, you shorten the sample time so much that you risk additional introduction of errors/variables that could have significant effects (whereas a longer sample time provides more time for errors to accumulate, but have a smaller impact).

Furthermore, I would assert that most people will not be able to discern the a change in acceleration of 0.04G/second, especially when you are already accelerating, which is an unnatural condition for the average person. Furthermore, humans are less sensitive to acceleration in the horizontal plane than they are to vertical (which is perhaps one reason why cars which squat heavily on acceleration "feel" faster). There is a great deal of research on human perception of acceleration, which is often visual, aural and also physically perceived by the inner ear and other organs (something called an otolith I think?). One of the perception tolerances that are often used for various engineering projects is 0.025 G for RMS acceleration. Furthemore, studies on horizontal elevators have shown that jerk must be below 0.2 g/sec to remain below the average detection level of humans.

Not to say that some people (perhaps yourself) aren't above average in the perceptive abilities - by the definition of average, some people must be! :)

Anyways, enough of the funky theory, let's just get some accelerometers in cars and check out the actual levels!! :)

SC

Guys, I've been following this thread for awhile, and all I can say is, get back to ENJOYING your cars without agonizing over this! All of you new owners are indeed very fortunate to own an RX-8, and I'm sure whatever is going on will be either found to be of little consequence, or easily rectified.

It's Sunday morning. Crank it up, pop in a CD, turn it up and go for a ride.

Sorry if this has been covered elsewhere but did SCC ever publish the dyno graphs for the RX-8 that they discovered had the stuck third ports? If so how does it compare to the other's that we've seen recently?

Originally posted by Lensman
Sorry if this has been covered elsewhere but did SCC ever publish the dyno graphs for the RX-8 that they discovered had the stuck third ports? If so how does it compare to the other's that we've seen recently? Good question... I dunno. We will have to see I suppose.

Originally posted by Lensman
Sorry if this has been covered elsewhere but did SCC ever publish the dyno graphs for the RX-8 that they discovered had the stuck third ports? If so how does it compare to the other's that we've seen recently?

I don't believe they did. I have that issue and they just said there was no point in showing the dynos since the port wasn't opening. But I bet their plots would look just like the ones we have seen here.

Originally posted by ChurchAutoTest
...Furthermore, I would assert that most people will not be able to discern the a change in acceleration of 0.04G/second, especially when you are already accelerating, which is an unnatural condition for the average person...
SC

I think you are forgetting that the drivers whole back will act like a preassure sensor and even a 0.08g difference would in my mind be noticable. If you try an lie down on the floor of an elevator, you'll sense the acceleration much clearer than if you stand on your feet. Your co-riders may think you're crazy though;).

/Elak

Actually Elak, all those hi falutin PhD and MD types and their controlled experiments say its the opposite - you sense acceleration better in a vertical plane (i.e. standing up). :)

Your skin/back isn't the best means for detecting acceleration either. Even if we limit it just to your back (say, 500 sq inches?), that 0.04 G/sec jerk rate (an additional 6 lbs of perceived weight) would equate to an effective pressure change of 0.01 psi. And that's not even taking into account the fact that the acceleration in the horizontal plane combines with the 1G acceleration in the vertical to create a vector with a magnitude smaller than 1 + 0.04G.

But again, just get an accelerometer in the car. The human butt lies.

SC

Originally posted by ChurchAutoTest
But again, just get an accelerometer in the car. The human butt lies.Are you saying people are pulling these numbers out of their ass?

Originally posted by 5Gen_Prelude
Are you saying people are pulling these numbers out of their ass?

:D

Pulling something out of their asses yes, but if someone has an ass that's outputting some actual numbers, I think we could get them a lucrative contract somewhere!! :)

SC

Originally posted by MP3Guy
Guys, I've been following this thread for awhile, and all I can say is, get back to ENJOYING your cars without agonizing over this! All of you new owners are indeed very fortunate to own an RX-8, and I'm sure whatever is going on will be either found to be of little consequence, or easily rectified.

It's Sunday morning. Crank it up, pop in a CD, turn it up and go for a ride.

I second this notion. I too am interested in this thread, but I'm not going to worry about it until someone from "corporate" actually gives us an answer. All I know is that the car is more powerful than my 1991 NA RX-7, but not as powerful as my 94 turbo - which I expected from day one.

Originally posted by ChurchAutoTest
...you sense acceleration better in a vertical plane (i.e. standing up). :) ...

I believe vertical plane in this case means falling (i.e. losing altitude) not whether you stand or lie down;)

...Your skin/back isn't the best means for detecting acceleration either. ... The human butt lies.
SC

If we simply look at the torque curves from the dynos before 6000 and after, the positive gradient before the peak is actually less steep that the decline after. Does my back register the acceleration before 6000? You bet! Thus I would expect to sense the decline (change - not actual value) after 6000rpm.

Back to a previous discussion about the impact of air drag. Where did you get the 720 inch CdA (you mean inch^2)? The Cd is quoted as 0.31, but I can't find a cross area value. If a Porsche 944 has a cross area of 2790inch^2 then the RX-8 can't be 2322inch^2?

If I put in the Porsche value (CdA=910inch^2), I get about 8hp loss to air drag at 45mph, and 20hp at 60mph. This seems to me to be too high to ignore if we are doing accelerometer tests in 2'nd gear. We are after all looking for a torque deficiency manifesting itself as 20-25hp in that specific rpm range.

/Elak

Originally posted by ChurchAutoTest

Anyways, enough of the funky theory, let's just get some accelerometers in cars and check out the actual levels!! :)


Funny you say that! Just yesterday I was looking at my accelerometer and wondering if that's what's needed to put to rest any suggestions that they need to be on the road to make the full power. Pity I don't have an '8 :mad:

-pete

Greetings everyone,

I am a newcomer to the RX community and have been watching this thread with great interest over the last couple of days. I am also a novice about rotaries, dynos, and the like, so I was hoping that you folks could help me out.

I saw the RX-8 for the first time last Tuesday, parked outside the Ritz in downtown Boston. I literally stopped and asked "what is that?" Since then I have been doing a lot of research, and have taken two test drives. (I have also driven the G35 and 330CI.) I have to say that I am a bit hooked on this car. One of my local dealers has the combo I want coming in within the next month (6MT, GT package, nordic green w/chaparral) and I am trying to decide whether to plunk down a deposit.

Even for a novice, it seems reasonably clear from the evidence presented here that there are "power issues" above 6,000 RPM. So, the questions I have are:

-- Do people believe that this is an ECU/tuning glitch, or is there something more fundemental that needs to be resolved?

-- If Mazada were to say "oops," what we really meant was 210 hp like the automatic, do those who have actually been driving the car think it is still worth $32k?

-- Is the hp problem a short-term show stopper? Should I wait until this is resolved before diving in?

I am not in any particular rush, but of course would rather have the car sooner than later.

Thanks

Nope, the research says you feel acceleration more acutely in the vertical plane of your body.

As for acceleration, can you really tell that the acceleration increases from 4500 to 5500 rpm? I'll bet you couldn't. But you're watching the speedo, perceiving your surroundings, hearing the engine rev, etc. and those all give you cues. If we put you in an isolation chamber and began accelerating it at the same rate, you wouldn't be able to accurately perceive the change in acceleration. As I said, research shows that a jerk of less than 0.2g/sec is difficult to perceive.

On the frontal area, I used a Cd of 0.28, I didn't realize the RX8 Cd was so high. Take the height of the car minus the ground clearance, and take the width of the car minus the sideview mirror width x2 (remember that car widths are quoted at the widest points and the mirrors account for a very small frontal area). With the higher Cd the CdA will be closer to 800 sq inches. I calculate hp losses at about 8 hp at 45 mph and 18 hp at 60 mph. This 10 hp differential is relatively small in terms of the deficit shown by the dyno curves. On the RX8 I tested, it produced 189 whp when it should have produced 220 whp, so you're looking at a 30 hp deficit with only a 10 hp differential between 45 mph and 60 mph in terms of air drag.

SC

Originally posted by ezradg
-- Do people believe that this is an ECU/tuning glitch, or is there something more fundemental that needs to be resolved? Any response you receive here will be pure speculation. It will be worth as much as a poll that asks "Which NFL team will go all the way this year?".-- Is the hp problem a short-term show stopper? Should I wait until this is resolved before diving in? That is entirely up to you.

---jps

Originally posted by ChurchAutoTest
Nope, the research says you feel acceleration more acutely in the vertical plane of your body.

Ok, you obviously have looked into it in more depth than I, so I'll back off that one.

...This 10 hp differential is relatively small in terms of the deficit shown by the dyno curves. On the RX8 I tested, it produced 189 whp when it should have produced 220 whp, so you're looking at a 30 hp deficit with only a 10 hp differential between 45 mph and 60 mph in terms of air drag.

SC

Rotarynews interview with the Senior VP of Marketing and Product Development, Robert Davis quotes 204-207hp to the rear wheels on the high power car. I.e. what we are trying to figure out if 15-18hp are missing or not. That means 10hp matters a lot.

/Elak

You're mixing your dyno's. The 204-207 quoted hp was on a Dynojet. To date, the cars tested on a Dynojet have averaged less than 180 whp. Or a deficit of at least 24-27 whp.

The Dynapack I use reads, on average, 10-12 hp higher than a Dynojet since the wheels are removed for testing. The average 2000-20001 S2000 (very similar drivetrain, power characteristics) puts down 212 whp on my dyno, the average 02-03 217 whp.

If we assume the RX8 should put down 7 hp more than an S2000, it should be producing at least 219 whp on my dyno, which is precisely 30 hp higher than what it did produce. Quite easy to resolve even with drag losses increasing 10 hp over the targeted speed range.

SC

1stRX8 got 184hp on his dyno. I believe that was a regular dyno. However the car had over 1000 miles, what was the milage of the one you tested?

So lets meet in the middle; we are looking for 20-23hp, overlayed by an 10hp drag effect.

Edit: Going back over the numbers I would compare the RX-8 with a 911 Carrera 2003 (RX-8 is slightly larger) - which would give a corrected CdA of ~940inch^2. That in turn means 20hp at 60mph, i.e. a 12hp loss over 45mph.

/Elak

I have had an accelerometer (a G-Tech pro) mounted in my car for a couple weeks now. I weighed the car on a certified scale so I can get some pretty good numbers. I have done numerous dyno pulls on many different roads and under many different conditions. I've tried DSC on and off. Every dyno curve I download to my computer is the same thing: the horsepower dips bad at 6300 rpm and the torque takes a dive. I have been watching the power as the car breaks in. From what I have seen from 900 miles to 1600 miles on the odometer, there may have been a 2 hp increase. I'm not holding my breath for another 30hp from break in.

Blah Blah Blah Ginger... Anybody have any actual information from Mazda on this as opposed to inconclusive dyno run evidence that we've had since 3 weeks ago?

Look, the 204-207 number was something uttered by a marketing guy at Mazda at a Q & A session, and NO he didn't say that was a dynojet number. He simply uttered the words with no specificity. If you want to ASSUME it was a dynojet number, or that he actually knew what he was talking about keep whipping yourselves into a fine froth if you've got nothing better to do.

It's become quite the speculation parade in here.

rx8racer,

Care to share your data with us?

/Elak