Dyno Results
 

I put my 8 on the Dyno Today with unexpected results:

Best pull was 184HP and was expecting 205 or so. Has anyone done Dyno's?

DSC was off
93deg F (results temp corrected)
ABS freaked but had no apparent effect
DSC light still came on solid but only after accidentally tapping the brakes.

I will scan the dyno results tonight.

Uh-Oh! Here we go again.
Conspiracy theorists: "START YOUR ENGINES!" :(

Dyno Results
 

I put my 8 on the Dyno Today with unexpected results:

Best pull was 184HP and was expecting 205 or so. Has anyone done Dyno's?

DSC was off
93deg F (results temp corrected)
ABS freaked but had no apparent effect
DSC light still came on solid but only after accidentally tapping the brakes.

I will scan the dyno results tonight.

interesting: your torque was a scarily smooth curve, with a range of ~100 - ~125 ft.lbs... hmmm...

btw: what's your milage, how did you break her in, and what fuel are you running?? have you had your post-break-in tune up??

Let me see if I can remember some of the comments from the last individual who put their car on a Dyno:

a) The car is still pretty new, even if you've put on the 600 miles. Try again at a few thousand.

b) One car, one machine, one test. Not necessarily valid enough to conclude anything.

c) You would do that to a car that's so new???

I think that covers quite a bit of the comments...

So, two dyno's now and both fall well below what the high-power should be, and that's taking into the effect the expected loss of power to the back wheels. I hope we start getting a definitive answer on what is going on...

give it another try when you got a few THOUSAND miles on it.

someone mentioned rotary engines don't make full power until a few thousand miles and the compression builds up?

I don't believe this. It's a myth.

then i don't know what to say....

someone with connections care to ping Mazda about this???

Which Pro-Technik dyno did you use please? Where was it (in Texas?) please?

Max torque seems right on the money. Asuming its about 130 ft/lbs with 17% drive train loss (from the graph) you get about 157-158 ft/lbs of torque at the flywheel. Sound right to anyone else?

I think it's genuine. You can see some marks around the top left, and bottom left sides of the image that are by no means even, which you would normally see in a computer generated image.

i've got two thoughts so far

1 - not all dyno's give the same numbers, dunno the reason why, but different dyno's give off slightly different numbers

2 - on a dyno you cannot develop your full potential power that you can while one the road, because your intake has to work harder to get air (since it's not being shoved through it like it when your car is moving), but also you are drawing in substancally less cool air (and thus less dense), usually warm to hot air depending on the layout of the air surrounding the dyno, if you want a more real world results get some large fans to help the inatke get cooler air

also it'd help if you rotated the pic like this

http://thewretchedbeaver.flippedcrac...03%20small.jpg

As has been suggested, someone who can needs to contact Mazda directly to clear this up. We need to know if the car is designed to produce low power for a while until run in or whether this is some other issue. If it's going to STAY like this then something is seriously amiss right?!

well it's definitely not stuck ports, as you can see clearly when each intake ports open at a certain rpm in the chart.

Re: Dyno Results
 

I thought that if the DSC was completely off it wouldn't come back on unless you turned the ignition off and restarted the car. Maybe it wasn't completely disabled.

Re: Re: Dyno Results
 

This is so.

The car has a thousand miles on it. I have been a rotary enthusiast for 20 years and have NEVER even heard anyone suggest that the engine would continue to build power after a thousand miles. I don't even remotely believe that.

I will certainly go back on the dyno a month from now to see the results. If it makes more power I will apologize.

While I do believe that not all dynos are created equal - I seriously doubt they would vary by 25+ HP. The shop that I went to does high-end work that is subject to scrutiny by other high-end shops. If the numbers don't come close to other dyno's they would not be working on $500,000 german race cars for long.

The RX-8 hardly depends on Ram-Air for horse power. We had the hood open with a few high-velocity fans pointed at the nose. A third gear pull takes at most 9 seconds or so. Not exactly enough to overheat the engine or have any real effect on the life of the engine. After five pulls in about 45 minutes - the run-to-run comparo was VERY similar. The ports open at exactly the same point every time. The HP is very consistent.

I could put a few thousand miles on it, take it out of the car, and put the engine on an engine dyno and expect to see just over 220HP. Even lowering the temp 30deg. wouldn't make 27 more HP and the Dyno computation takes pressure, temp, and humidity into account.

The pulls were made with DSC on and off - it made no noticable difference. Once the system detects a gross error it apparently shuts off and the light (car with squiggily lines) stays lit constantly. If the disable switch does not disable it fully then the dyno results are inconclusive. That would also mean ther is no easy way to check up on Mazda claims of power.

This was never meant to be a conclusive test. I would hope that a few others will take a dyno run and see what they get. I plan on contacting Mazda to simply ask why I might see this result on a dyno. I look forward to hearing some answers.

I want my 247HP!

Mileage: 1010 miles

Fuel: 93 octane although I bet that would make only a slight difference.

Break-in: I drove it on a 600 mile road trip. Fairly easy driving. A couple of bursts here and there. Generally following the rules, however I do believe that the break-in specified in the manual is exceptionally cautious.

What in the world is a post-break-in tune up? changing the oil? Checking the tire pressure?

Simply pressing the button disables the DSC (and traction control?) until and unless the ABS is engaged, apparently. Pressing and holding the DSC button for several seconds disables it completely until the ignition is turned off and back on again. When in this mode, the DSC OFF and Traction Control ("slippery when wet" lookalike) lights both remain on constantly.

actually engines do get more power as u put more miles on it, to a certain extent. one of those car magazine did an article on it, they had a is300 from when they first tested it and then they tested it again at like 20000 miles and the car gained like 20% more power and a few tenths quicker. several people at is300.net can also confirm power increases

Next time hook up a voltmeter to the Throttle Position Sensor so you can see if the throttle is open 100%... with an electronically controlled throttle and DSP/TCS you never know whats going on unless you monitor the TPS

The dyno shop is at most 300ft from my office. I will take there and do a pull every few thousand miles. I certainly hope the power increases, but my hopes are low.

Please dyno in fifth gear (1:1)
You should get 210-220 hp depending on rear tire pressure, and state of engine break in

Take a look at the air fuel ratio. It gets progressively richer as the motor goes past 5,000 rpm. This keeps internal parts nice and cool, and keeps the stresses down on the bearings and gears.

The motor is pig rich by the time it reaches 8,000 rpm.

Who knows what the timing curve looks like.

Mazda is simply running the engine in safe mode while all the internal parts are getting to know each other.

This is a wise move for any performance car. Just imagine what the lot jockey, salesman, and test drivers will do to a performance car before it even clocks 20 miles!

Don't worry, just keep driving.

Paul Yaw
Yaw Power Products

Please tell me why this will make a difference, other than making the pull last longer and being harder on the car. I pulled it in third gear.

It'll make the drive train loss a little less.

Thing I don't get is that the peak torque looks right in line with what you should expect.

I did notice that. I don't now if the exact ratio is accurate but it definitely starts moving toward the conservative side. Are you suggesting that the ECU will change it's maps after a certain mileage?

FYI: About two hours after I left the dyno shop - a new Boxter pulled in. I had returned to pay the bill and watched the boxter run. It was within a few HP of published numbers (201HP) with a 16% DT loss. It is easier to believe the dyno is working accurately.

It is likely that the ecu will switch to a different fuel map after certain mileage. I know mazda did that to the turbo 2nd gen rx7s. Don't trade it in yet!

In every gear (except 5th) power flow into the transmission via an initial gear mesh, then another for the gear you are in. Driving in 5th the power doesn't flow via any gear meshes in the transmission, and the only gear mesh is the ring and pinion. So 3 gear meshes for 1,2,3,4,6, and 1 for 5th gear.

So you could get at best 10% better power to the rear tires

What was the rear tire pressure, 30, 35?

Can someone please explain the dips in the torque & hp curves @ 4,000 , 6,400 & 7,400 rpm's.?

The extra intake runners are opening creating turbulence for that 1/4 second or so.

I am really only trying to figure out if the car does what Mazda sais it does. I can believe the break-in fuel map theory. Third gear should be in the 15% to 17% power loss range. If that is correct the rear wheels should see about 205HP at 17%. If you say fifth gear is maybe only 8% or so the out put should be - 227. It is still a smidge (21hp) short on power. I am not hugely worried at this point. I will be patient and go easy on the engine for a while and post the results of dyno pulls in another month or so.

I would really like to see what others are getting so that we can get a clearer picture of what to expect. I hope there are a few out there that aren't too chicken to put thier new baby on a dyno.

This should definitely proove interesting...
http://www.rx8forum.com/showthread.php?s=&threadid=6598

That is WAY rich, I own a second gen and ive seen them pick up 10+ HP from leaning out the factory maps. A map that rich will most likley pick up 20+ from leaning out. Here is an image out of a S4 NA rx7's factory service manuel confirming the mileage switch. If the 8 is the same, dont try dynoing it until 20,000 miles. I'd expect gas mileage to pick up after that too a bit.

Also torque is about what it shold be because it doesnt get super pig rich untill higher rpm, but i suspect this will go up after 20k miles too, as it starts to get rich at 5000, and torque peak is suppost to be higher than that.

the rpms at which each secondary intake ports opened up?

OK, having read the 20,000 mile thing, I feel as though I can go to sleep now.
One last thing, so y'all have something to beat up on while I lay my weary head:eek:
I can appreciate the new dyno's nowadays, but I've done some more old fashioned dyno testing in the 70's. The method used was definitely not what you would consider to be automated, where a "pull" is done in 9 seconds. It was done by establishing wide open throttle at certain rpms. The head guy would yell "mark!" and the group would record their gage readings at that time. This was done at various rpms throughout the range. Then we would do the math & plot the curves.
This 1/4 second of turbulence might have a dynamically detrimental effect on the whole upper rpm range of the performance curves if the dyno testing doesn't provide enough time for things to re-establish steady state. If, say, you establish a steady 8,500 rpm @ WOT for 5 seconds minimum, would the hp read higher than what was recorded here? You would have to perform both test procedures, one right after the other, I think, to answer that one conclusively.
I'll be dreaming of all your replies. Can't wait to read them tomorrow morning!;)

It all comes down to at what point millage, break-in, etc. will our cars do 0-60 in 5.9s?

That's all I care about. I believe these Dyno results are accurate (someone else got 178 a few days ago), but they don't matter as long as we are getting sub 6.0 second 0-60 runs.

I do have another question. How do they get these air-fuel readings? from the OBDII port? They do seem quite rich. I wonder if this also has something to do with the considerably poorer than EPA millage that some people are getting.

One last thing, if the fuel maps do change at 20,000 miles like the RX-7, that is awfully long break-in period. Wouldn't even something like 5,000 be overkill?

-Mr. Wigggles

Ps. I'll be saving a few nickels for an FI system regardless. The extra rich mixture will come in handy then :p

Here's the graph of the torque from the Mazda press-kit:

Up to 6000 RPM 1st RX-8's graphs are within the curves provided by Mazda at close to 80%. (20% drive line losses is respectable). It is after 6000 RPM that the engine doesn't take off like it is supposed to. By 8500RPM, the output is 6% lower than it should be (assuming 20% driveline losses) or about 15 Horsepower.

Hopefully that extra 6% will be restored., but the Dyno helps explains why the people who are babying their cars right now aren't typically complaining about power. They aren't past 6000 RPM yet so they don't know what they are missing.

Hopefully the extra power in the higher revs will kick-in pretty soon for 1stRX-8.

-Mr. Wigggles

Well presumably it isn't a sticky tetiary port because the dyno graph shows the port opening. Otherwise that would be the obvious culprit right?

Definatly not a stuck port, also a stuck closed sixth port would cause a much bigger loss, like 30%+

From experience with a mildly modified 84 GSL-SE engine, I played alot with the 6PI actuators to get a sense of thier importance. The difference between fully open and fully closed wasn't 30%. The problem I had wasn't getting them to open at all, it was getting them to open completely.

My take on the graph blips is that they are the ECU activating a pre-programmed map change in anticipation of the ports opening - Not entirely the ports themselves if at all. When I overlaid 5 runs on one graph the blips happen at exactly the same point, the same shape, and the same amplitude. I would expect that from a computer over a vacuum driven actuator. I do believe the 6PI actuators are fine. I can test them while driving if they are anything like the previous actuators.

FYI, the port actuators are electro-mechanical on the Renesis, not vacuum-operated.

That would back up his theory even more.

Yawn.

Oh! Sorry, I just got up - I wasn't refering to this thread, of course. You know.

Mr Wigggles torque chart matches in shape that of yesterday's dyno results (shape, not values) (without the 3 blips) so I'll not try to defend last night's theory of mine.

Eccles, man, why are you sitting @ your computer & not in your new driver's seat? He he;)

No further comments @ this time...

To boost the break-in theory:

BMW's and to a lesser degree Audi's are famous (infamous) for this.

Most recent example is a long-term Audi 3.0 in Car And Driver that ran 0-60 in 7.2s new and 6.5s at 40,000 miles. This is similiar to the kind of difference you see in some BMW's after 20,000 miles.

Friction!

Re: Re: Dyno Results
 

This is the same issue that was suspected with the first dyno pull, isn't it?

1stRX8, could you please tell us exactly HOW you turned off the DSC? If you just pressed the button, then it isn't off. From your description about the warning light coming on midway during your run, you only turned off the TCS, not the DSC.

The owners manual doesn't document the procedure to turn the system off completely - you have to hold down the button for over 5 seconds or more, and then both warning lights will come on. At that point, you can't turn it back on without shutting off the car - the button won't do anything.

Re gearbox efficiency - the reason dyno pulls are usually done in 4th gear is because of the 1:1 ratio in most 5 speeds (and also because it doesn't rev so fast, so transient/dynamic effects are minimized, so a more accurate pull is recorded). The mechanical differences between 3rd gear and 5th gear on the RX-8 might only be a couple of percent, not 8% or whatever you responded with. The typical number of 15% - 17% is for the most efficient drivetrain path, which would be 5th gear in the case of the RX-8.

I'd still say that the DSC is a likely issue with your pull.

Regards,
Gordon

Even though I also put forward the DSC as a possible problem in that other post about a dyno run. And many time that is the issue.

The graph doesn't show that. It the TC part of the DSC cut-in you would see a very clear drop in the torque curve where the system engaged. And the curve after that would look haphazard as the DSC tries to modulate engine power and/or brakes.

There is still a possiblity of the DSC since we don't know exactly what the software code is, it's possible it has a level of very minor modulation on the brakes only that would act like a parasitic power loss.

Theories, Theories, Theories:confused: :p

thank GOD!

no more stupid vacuum tubes!!!