A member in one of the Miata clubs posted a link to an article regarding the relationship between torque and horsepower. I thought it might be of interest to some here:

http://personal.riverusers.com/~yawpower/tqvshp.html

Mark

Then they get sued by a few hundred pissed off people who feel betrayed, lose a ton of money from the horrible publicity and probably suffer a huge pullback from Ford.

Jeez, isnt that obvious? Again, why worry about it right this very second?

I think the MPG will be a bigger turn-off than the HP. I can't see too many families ponying up 30k for a 15-18mpg car. I'm more concerned with the low MPG that I'm still getting (17-18s) as I was expecting abot 22 to 25.

Ram-Air effect in high power Renesis
 

The tech highlights CD talks about the variable fresh air duct (not ports, they come after the duct) being an "important distinction between the high power and low power engines". According to the same CD the variable duct opens above 5500rpm. So maybe there is some amount of inertial ram-air going on to achieve the full effect. Thus more power is developed at higher vehicle velocity. With a dyno setup that doesn't force air into the ducting at 40-100 mph this would result in lower performance.

Indeed yawpower pointed out earlier in this thread that the car runs rich after about 5000rpm, now couldn't that be a result of not ramming in enough air?

The above theory fits both with the dyno results and my own observation that the car does have more power above 7200rpm when I drive it.

/Elak

I doubt Mazda is blowing 100mph+ air at the intake during tests to make the 247hp. That would insure that any 3rd party measurement of power would always indicate lower power.

Mazda would have to respond to all of us with something like..."Our new Renesis engine is capable of producing 247hp....but only at 100mph or greater. For those of you intending to autocross and such, your cars are only 210hp. Sorry."

Ok, 1stRX8 - so take the lower number instead, 40mph. That is what you're doing at 8500rpm in first. Maybe 40mph air force is what is required?

Mazda doesn't promise 247bhp on a dyno, so I don't see why that would prevent them from quoting a higher, Ram-Air effect dependent number.

Just out of curiosity, when you red-line your car in 1'st and 2'nd, does it feel like the acceleration diminish after 7250rpm?

/Elak

Elak -

It does seem to diminish a bit after 7250. Could be psychological because I am looking for it. I don't even dream of having senses so keen that I would really know. I would like to get a G-tech or similar device to confirm what I feel because I certainly feel good driving the car.

I won't feel as good when a S2000 shows me his rear plates. I guess if that happens I could just yell "MAZDA OVERSTATED MY F***ING HORSEPOWER - TRY AGAIN IN 20,000 MILES AND I'LL BLOW YOUR DOORS OFF!!"

Half the fun the RX-8 is talking about it.

elak,
the 247 bhp number is what the renesis should make on an engine dyno at the crank. Why would it be a ram-air dependent number? You just can't put a 5000 cfm fan in front of the intake and then do the sae bhp test to inflate the number. All manufacturers would do that now wouldn't they?

Bummer - wrong again
 

From what you are saying SAE guidelines ban any velocity related forced induction, even if it is real? Ok, that does shoot down my argument.

I guess on the positive side that means that the engine will actually have more than 247bhp at speed;D.

/Elak

We can only wish for such luck. Besides "Ram Air" reminds me of pontiac [I know the p is not capitalized, it doen't deserve it]

The poor showing of the dyno's have been backed up by racing the 210 and 247 HP versions of the cars against each other. The 247 BARELY beat out the 210. Imagine buying a 330 and barely beating a 320 and you'll understand why this is not just about numbers.

210 and 247 very close in racing?
 

I looked through out this thread and cannot find any mention of the 207 and the 247 being very close in performance. Can you point me at your source of this info? Thanks:confused:

Re: 210 and 247 very close in racing?
 

Look here:

http://www.artex.co.jp/Pages/Car/RX-...03_6-26_03.jpg

As far as I know nobody has translated the article in this forum, so the circumstances are unknown.

/Elak

Do you drive exclusively highway miles? Given the released car's EPA estimates, that seems a rather high expectaton to me...

According to my understanding of the variable duct system in the high power RX-8, "ram-air" has nothing to do with it. The variable ducts are designed to resonate at complementry frequencies to the engine RPM, and are variable to match a wider range of RPMs. Effectively they are turning the intake into a Helmholtz resonator, and tuning it much like a trumpet (with different lengths of intake pipe that they switch in and out). This is also the same technique that is used to design base ports for speakers, as well as a whole host of other applications.

But long story stort, I seriously doubt forced air is required for the variable tuned intake sytem. The sucking intake pulses from the engine should be more than enough to excite the resonances.

Re: Re: 210 and 247 very close in racing?
 

I'll do the honor and translate the article for the forum the best I can. (just hope I don't get flamed by some A-hole for taking my time doing this)

The top of the article states: Performance Test: Acceleration times of 250hp and 210hp models not much difference!

250hp 1/4 mile 14.97s 0-100km/h 7.04s
210hp 1/4 mile 15.02s 0-100km/h 7.10s

Then the article gives some 0-100km/h time for other Japanese sport cars. I'll just list a few:
4.6s WRX STi
4.8s Evo8
5.8s 350Z
5.9s Q45
6.2s S2000
6.4s SC430
7.0s IS200
7.04s RX8 6MT 250hp
7.10s RX8 5MT 210hp

Now onto the summary of the article:

Article states naturally most people assume high power version to be significantly faster than normal version. In the case of the RX-8, the JDM spec 210hp (22.6 kgm) yields a slightly better torque curve compared to the 250hp (22.0 kgm)model due to intake design. Under normal driving, the 210hp version has more torque up to 6000rpm than the high power version. Despite the advertised spec difference on the two models, does the high power version actually feel more powerful?

The testers also stated much lighter 16' wheels on the 210hp model and 5MT transmission might help the lower power model achieve better time. (on top of the better torque curve)

On a side note, Japanese testers and drivers do not like to drop clutch from high rpm due to the obvious potential damage to the engine/tranny/clutch. This type of suicide driving is often frawn upon in the JDM world. Maybe that would explain why the RX-8 time from oriental magazines have been lacking behind the optimistic projections from preproduction models in US. Then again, how many of you will actually do 8000rpm clutch drops on your brand new RX-8?

Thanks Skyline..

It's signifigantly lower than the 5.9s gotten by the US mags, so.... *shrug*.

I think we will have to see... I've noticed a top-end deficiency and I'm hoping it will get remedied but I dunno... we'll see...

Those are the engine valves (ssv,vdi) you are talking about? The variable fresh air duct sits before them. At least this is my understanding from the CD-ROM.

/Elak

Nice job Skyline,

One would think this would be an even bigger problem in Japan then since they have a choice between a 6sp 250 and a 5sp 210, with the former costing more presumeably

btw: I forgot there is also a second page on that article. I don't want to go into all the shifting details and such. Seems that they drooped or sliped the clutch from 5000rpm, and shift at 8000rpm. The testers noted the smooth Renesis engine and its signiture tone. They were very impressed with the performance of the acceleration in quarter mile until they saw the numbers. (Apparently the car felt much faster than what the stop watch says) They also mentioned the acceleration tapered off after shifting into 3rd gear.. The 250hp model feels slightly faster than the 210hp model, which is confirmed by the data. (but not by much) Amazed by the closeness of the quarter mile performance between the two models, the testers arranged to line up the 210hp and 250hp side by side and gave them a go. The result was quite shocking as the 250hp model beat out the 210hp by nose length. 14.97s vs 15.05 sec.

Article indicated factors that yield these surprising results included 1) Better torque curve for the 210hp model, lighter wheels and tires, and 3) Final gear ratio.

Here is the break down of specs.

250ps @ 8500rpm
22.0kgm @ 5500rpm

210ps @ 7200rpm (Redline of Type E is 8000rpm only?)
22.6kgm @ 5000rpm

Gear Ratio
--------250hp--------210hp----
1 ----- 3.760 ----- 3.483
2 ----- 2.269 ----- 2.015
3 ----- 1.539 ----- 1.391
4 ----- 1.187 ----- 1.000
5 ----- 1.000 ----- 0.806
6 ----- 0.843 -----
F ----- 4.444 ----- 4.300

Now for another piece of info that will likely tick some of you off - The tested both 210ps and 250ps models in a AutoX type course that included 5 slalom turns, 1 hairpin and one sweeper. The 210ps beat out the 250ps model 3 times on the course. They were comparing the sport suspension on the Type S and Type E. I'll read more about it later, but the result is rather....... insane IMO. This begs the question why would anyone buy the 250ps Type S RX-8 in Japan over the cheaper, lighter, more agile 210ps Type E.

They shift both cars at 8000rpm? That seems strange, since the high power engine only will deliver 220-240hp in that interval, rather than the 240-247hp in the 8000-9000rpm.

Do they say anything about the max speed for the two cars? That could be an argument to buy the higher powered one.

/Elak

The 210ps model has a redline of only 8000rpm. Thus they did shift at the redline for the 210ps model. They said both cars will accelerated to redline. There is no reason to believe they would shift the 250hp model at 8000rpm instead of 9000. On a side note, the torque curve of the 210ps is higher than the 250ps model up to 6000rpm. At the 7000rpm range, both models yields about the same power.

Minor correction here, it seems that Type E is only offered in automatic trim. So when I said 210ps Type E I actually meant the 210hp 5MT base model.

6MT 250ps Type S 18" wheels Bose upgraded brakes + sports suspension

5MT 250ps Base - 16" wheels base everything, but standard DSC and LSD. This model retails for 2400000yen, which is a tad less than $20,000 USD.


What gives? Mazda! bring over the base 5MT RX-8 over and just forget about the 6MT since it doesn't perform that much better anyhow. (maybe on paper it sounds better with 247ps. However most people buying the RX-8 aren't interested in high horsepower to begin with. The 210hp gets better torque curve (more practical), better gas milage (cheaper) handles better (according to the article data from the AutoX course) and can accelerate just as good as the high power model. The JDM 5MT retails for around $3k cheaper than the Type S (US 6MT model) I'll bet a whole lot of people would be interested in a 5MT 210hp base RX-8 with a base around $24,500. Now THAT would be a reasonable and attractable price and packaging. Mazda need to realize they are only digging themselves a hole with high profit margin and low volume sales. They need to lower the price on the car and sell more of them to increase revenue.

so does anyone else take issue with the idea of being sold a car that limits its performance for the first 20,000 miles? that's like 20% of it's life (assuming a 100K turn over)! even if you're going to go for 200K+ it's still 10%.

in other words i'm getting 8% less car for up to 20% of it's perceived lifetime. i don't like that without being told up front that's the situation. i also don't like wasting a bunch of gas just to blacken my exhaust. i don't find the "it'll be okay after 20K" to be an okay answer.

am i crazy?

Why were you expecting that? The EPA sticker on the window says 18 city, 24 highway. Are all your miles highway miles?

Just got back from the dealer after looking at a rx-8. I talked to the dealer about the HP issue and he said that they had info from dynos putting the HP at the wheels at 250 and 280 at the flywheel. Personally i think they are full of sh!t. Thought i would let you guys know how stupid these people are.

The dealers oftentimes know much less than the customers.

I was told by my salesperson that I probably know more about the rx-8 than anyone at the dealership. I'm glad she didn't just tell me a bunch of BS; instead she told me nothing about the car other than that it's "really nice."

There is no way I will be happy with under 190whp. Come on, the S2000s are getting into the 190s!!

The Mazda dealership here explained to me the tire repair kit goo is specially made for Mazda. According to him, the goo won't destroy the tires because they will 'sublime' after the tire is properly repaired, thus making it as good as new. Anyone knows where I can get this type of 'special Mazda goo'?

Anyways, any news from Mazda regarding the power issue yet?

I have a Mazda Japan complete brochure in my hand.
3 models:
RX-8 Type S: 250PS, 6 speed, cloth seats, ABS/EBD, 18", Bose.
My Japanese is too poor to figure what else is included.
$2,750,000 Yen (Roughly 23,288 USD$)

RX-8 : 210PS, 5 speed manual, or 4 speed automatic
cloth, 16" wheels, ABS+EBD. LSD+DSC is optional.
$2400000 Yen )Roughly 20,328 USD$

RX-8 Type E: ABS+EBD, LSD+DSC, 16" wheels, Bose, leather, 210PS, 4 speed automatic.
$2,750,000 Yen (Roughly $23,288 USD$)

Add freight, etc., USA emissions and bumpers, left hand drive, perhaps another $5,000.

Horsepower issue
 

It sounds like this whole horsepower issue is with the 6 speed model. Is this true?

If it is, I am glad I got the slower automatic.

I hope you asked for their dyno printouts. I hate the fact that you can't trust any dealer for any brand. They will tell you anything to sell a car, even if it is pure bs. :(

On another nore, could the U.S. spec RX-8 be making 228hp at the crank like Mazda re-spec'd the Euro version? I can't imagine the Euro version having to deal with stricter emissions that the U.S. version.

Re: Horsepower issue
 

Well, the automatic models are still slower, but only because of its transmission. The power output on the 207hp and 247hp are a lot more similar than what would appear on paper.;)

Bah, and the 6-spd version may not be as much faster as expected, but it sure is a lot more fun that a slushbox.

I asked were they got their info they said that all the major magazines were putting out those numbers for their dynos. I was like bull sh!t but didnt want to make a big deal out of it. I told them i have seen posted pictures of more then one dyno with the RX-8 putting out 180 at the wheels. One of the guys said that the car is still really new and to give it some time and everything will be worked out. Thats kinda what im thinking.....hope its sooner then later. BTW when it comes down to it i would rather drive the 6 speed then the auto even if the 6 speed was only putting out 150hp at the wheels.

One fellow installed a GTech unit and did some runs.

Results are posted at:
http://www.rx8forum.com/showthread.p...394#post101394

0-60 in 6.021 seconds.
1/4 mile in 14.037 at 101.39mph

COOL!

:D :D :D :D :D :D

I dunno if you folks know this, and for what it's worth.. the RX-8's window sticker clearly states..

1.3L ROTARY ENGINE WITH 247HP

:eek:

okay i owned a G35C reason i said owned is cause a week ago it got totalled...if you check the G35 forums right now you will notice they are complaining about the same amount of power loss...its seems that the g35 is rated at 280 but being dyno'ed after 4k miles only gives out a reading between 220 and 240...right now i am lookin at either getting the g35c again or a rx-8...both being high compression motors i think is something we all need to take into account... for instance most of us have delt with 9.5 or lower compression motors with turbos...now we are dealing with 10:1 or higher compression...I could be wrong but maybe having a highly tuned n/a motor is what is causing the shortage in hp..cause even the e46 m3 with a rating of 333 is dyno'ed at about 280 or so... and its compression is 11.5:1... to come down to it mazda didnt make this car to be sports car...it ment it to be a fun to drive in the mountains and in the city kind of car not for a race track...also does anyone know what mazda stated the transfer loss to be...cause if they state 247 then by law they also need to tell you what can actually be expected under pre-written conditions other wise its false advertisement... i think instead of having 16 pages of posts with everyones opinions we should just write to Ford the owner of mazda and tell them we want visual proof of the 247 either on an engine dyno or a reason on why there is a 40hp loss... if you disagree with me thats cool heck i disagree with myself...

...you're wrong. :)

Could you PLEASE give us a link to this? (PM me if you want) I'd be very interested in seeing what was going on...

Thanks!

The G35 power deficiency issue arised earlier this year, when people started to compare their G35's to BMW counter parts. Some people felt the BMW's 'felt' faster. Some G35 owners complain about the fact that BMW engines with lower power ratings generally performs on par with higher power Nissan engines. (Check Automobile article for the G35C vs 330ci comparison)

When people dyno their G35 sedan and coupes on the FA forum. The same was performed on the MY350Z forum. The basic complaint was that the powertran loss on these new Nissans are about 17% (optimistic owners were expecting 15% from the manual) and that lower models such as Altima, G35 sedan are underrated. Base on several dyno results, the G35 sedan generally dynos in at 220(+5)whp, the G35 coupe around 230(+5)whp, and the 350Z around 235(+5)whp. Do a search on the FA forum or G35drivers forum to see more dyno results. Seems that the difference between G35 sedan and coupes are much less than 20hp, and 350Z dynos in around 5-10whp higher than the coupe. Quarter mile slips on the G35C have been right around 14.1-14.2, which is not too bad.

I don't want to sound like a sales person here, it just so happens I know info on the G35 and G35C better than most on this forum.

Too bad you don't know anything about the RX-8 and you're still here?

*sigh*

CAUTION
 

No offense Herc, just passing the note from fellow moderators. ;)

Fellow members requested info regarding G35 dynos (which as far as I know, I am the most knowledgable person here) thus I post the information for the benefit of those who are interested. If you got anything to say to me, feel free to PM me~ (Can't guarantee I'll read them, but at least you won't look like an @)#$#$ on the forum)

btw: Does anyone here know how the Miata owners back in the 90's found out about the power issue and managed to get benefits form Mazda back then? It would be great to have an experienced Miata owner here to aid the RX-8 owners.

Out of curiousity, are you on those boards, howling for Nissan to "make it right!!!"

Cuz that sounds like a familiar issue, and honestly the threads look exactly the same (really, you could replace the numbers, and names, and have the exact same arguments, even down to good performance numbers against not-so-pretty dyno's), but I missed the RX-8 people over there, calling on Nissan to fix their huge mistake... :confused:

KyngNothing, well, at first we were somewhat concerned with the power issue on the VQ35DE engine. Once the dyno numbers came in though, it was pretty obvious the Nissan engines are more or less on target. 17% Powertran loss is pretty standard on the new 6MT sequential shifter and 2 piece drive shaft on our cars, so there is nothing to complain about. If our cars had dynoed with 30% power loss (under 200whp dyno) though~ you can bet we'd be making lots of noise.

Resident Nissan engineers (real Nissan employees who knew what they are talking about) on the G and Z forums explained the transmission loss coefficiency, drive shaft difference and intake difference between the G35 sedan, coupe and 350Z promptly. Everyone came out more informed and were pretty satisfied with the explaination. Now if Mazda would release a reasonable explaination regarding the power loss, I am sure we won't have to scream bloody murder here.

How long did Nissan take to release those explanations?

Ps: apparently some people missed the explanation, as there are still threads bringing it up... :eek:

Nissan lies more!
 

I *used* to own a Spec V.
Nissan claimed 185hp for those.
Actual dyno was 140 - 143.
That is 22.7% below.
Then they dropped the claim to 180hp
That is 20.555% loss.

If we assume 17% loss ( not unreasonable) we see 205whp.
As the dyno results we are getting vary from around 180 to 192, I do not think we have seen much definitive yet.

If we get around 200 I would be satisfied.


As I mentioned before on these forums, my RX-8 is pulling well above 6200rpm, so I do not have any big issues so far.
If anyone is expecting to see dyno runs above 200 I think they are either naive or overly hopeful.

Just my opionion..

As I remember.... it was less than one week before both dealership representatives and Nissan engineers provided answers and dyno data. More user dynos rolled in after that to confirm their explanations, and people were happy after that. We had drag results, dyno results, tech explanations, and G-Tech pro numbers within a month. The original suspicion of the lack of power didn't arise from dyno data, but rather 'butt dyno' from some people who test drove the car.

Honestly, the C&D 5.5s on a loaded G35C model seems exaggerated IMO, as most other publications were getting around 5.7-5.8 on a base light model. We have had G35C owners running 14.0-14.1s on a strip, but they are expert racers with years of experience. Similarly, I would question the 5.9s figure on the preproduction RX-8 until we see some time slips from forum members. We need more data from everyone who owns a RX-8 to make a better evaluation. (no, stop watch numbers don't count, and G-Tech Pro alone is not enough. We had people reporting 0-60 on the G35C 5.3s on a G-Tch..... to me that;s just BS)

sequential shifter? What do you mean by this?

accurate hp reading
 

if any of you are into car tv programs you might know about the uk program called Top Gear if not let me explain to you who they are...they are a group of 3 guys. one being an ex f1 racer another a tech guy and the third i think is just jo somebody...but anyways they usually test cars at full throtle around town and on the track... on their site about the RX-8 http://www.topgear.com/servlet/tg?DE...Number=02.html they declare the 6 speed to have 228bhp...and they usually dyno the car and not declare what the car company states...so maybe this will help on the whole hp thing

seeing as thats teh Euro model, its dead on accurate


edit:
actually, i think DEAD ON accurate would be 230bhp but 228 and 230 are the same