If you have Dyno'd an RX-8...
 

...when you did it, did you tie together the sensors that sense the wheels are not all moving and put the car into "limp home" mode?

If not, it's beginning to look like your results are going to be way low, as limp mode severly retards engine power via the ECU. See this thread for more details: https://www.rx8club.com/showthread.p...threadid=16738

Something else to consider: If a good burnout does indeed also put the car in limp mode, then any of our 0-60 and 1/4 mile times are going to be less than the car is truly capable of... stock... including the test results of all the car magazines. So 0-60 in 5.9 sec and 1/4 mile in 14.5 secsonds may be slower than the car can do with nothing more than a simple sensor-defeat mod.

Interesting, no? :)

hmmm... anybody know what he is talking about? sure sounds good though ... i hope you are right!

The car has wheel speed sensors on all 4 wheels. They are used for the ABS and DSC. You can turn off the DSC when you want to race, but the sensors are still active (for ABS). Every major system in the car talks to the ECU (EPS, ABS, DSC, etc.). If the ECU is told there is a problem it goes into "limp mode" (lower power output and perhaps even poorer mileage). This mode is triggered when you spin the rears for more than 3 or 4 seconds, in a burnout, for example. To reset it you have to turn the car off and restart it. This also affects the car when on a dyno.

We are working on a module that racers can install that will fool the ABS into thinking all wheels are spinning at the same rate. I say "racers" because this is potentially dangerous, and should be done by experienced racers only. Prototype should be done this week. More on this later.

I think it's great a fix for this is in the works. But what blows me away is the impact this discovery may have on both dyno output AND performance stats, and that this little fact has not yet been discussed extensively.

Hymee....
 

Check out the 'Hymees cat back' thread in the Aussie forum, they are finding the same thing.....

S

I really don't think that it will best the 14.5 times etc. I've got extensive 1/4 mi drag racing experience( hence the name) and this feels like no faster than a mid 14 sec car. BTW I am both big and asian.

So if your name was BiggerAsian or BiggestAsian, would that give you more experience? How does your name give you extensive 1/4 drag racing experience??? By the way, drugs are bad.

I am Big Asian, end of story.

I don't see how 0-60 mph times of 5.9 and 1/4 mile times of 14.5 could have been achieved in limp mode. Those have to be true numbers.

Is there any way to tell that the car is in limp mode, ie a CEL?

From our experience yesterday, the car does not throw a CEL.

The DSC light goes off AND the ABS light comes on. The wiggly line symbol stays on. Turning off the engine and re-starting did not reset. We had to back the car off the dyno, drive a short distance (20m or so), and drive back on the dyno.

I am amazed on the comment "But what blows me away is the impact this discovery may have on both dyno output AND performance stats, and that this little fact has not yet been discussed extensively" (not being critical). I have seen thread about this for a while:

https://www.rx8club.com/showthread.p...threadid=11614
https://www.rx8club.com/showthread.p...threadid=11656

I tried to think it was BS at first, but am always happy to be proven wrong. Looks like I was.

BTW - A word of warning for the uninitiated. I am not calling anyone on here a liar or unscrupulous. But I must say it is very easy for a dyno operator to fudge the power reading by the small amounts (<10kW)that have been reported for cat-backs. In fact, I read an article in a mag yesterday and they showed how they could fudge 50kW between runs without altering the engine at all!

I prefer to use an independant dyno operator for my exaust runs. For tunes it is harder as a Tuner needs a dyno to do his work, so he is also my Dyno man. I trust him though.

Cheers,
Hymee.

So being a big asain your like 5'9"??As far as performance numbers go,if you spun the tires long enough to throw into limp mode your time would still suck.Now dyno thats another story.

All this HP and dyno crying is getting old.. Just accept the fact that the RX8 is a low 15 seconds car and a high 14's car if its properly launched with 8000Rpm clutch bomb..

Nice Hymee,

I just recently had my car dynoed and only came up with 179 whp and 135 tq on SP engineerings dyno.

Now only if we knew what percent of the actual power was missing. Im thinking its retarding the timing and adjusting the fuel up to a set maximum ammount since we all seem to be falling in the same ranges. I could be talking out of my arse tho too its just a thought. I just wish we had an "valid" us spec hp number to use to figuire stuff out with. Not some magical number Mazda decided to pull out of their arse.

Thanks for the info tho its very much appreciated.

I think the crying is over........what has been brought to attention is people want to know how much hp they really have.

We want a valid baseline as im sure you did when you got your Z. I know i do thats for sure.

I guess we could base it on times at the track but then that would mean on the track the M3 350z and the RX8 all share the same times stock.

Now that cant be right can it Mr Z?

wow...this could be scary...even for Mazda..."lies, lies, lies" as the Thompson Twins so eloquently put it...oops...showing my age there....

I thought that this was settled by canzoomer a few months ago?

Vince

Yes, a few months ago Canzoomer discovered this, but did not do too much investigation. All of us who followed that thread apparently missed the implications of this limp mode thing too, myself included, until recently. Now that it is coming to light, we may have a VERY simple mod that will yield significant results. Time will tell.

I thought it was settled as well, but it come to the fore again.

Be wary of using a dyno run in isolation to give you an absolute indication of your engines capabilities. A dyno is tool used by tuners to determine relative changes in performace characteristics. What I mean to say is even though your car pulled 170rwHP and mine pulled 160rwHP does not mean a lot, as there were measured on different equipment.

I am starting to believe the "safe mode" theory. As explain by the "Offical Mazda" explanation, the computer dumps in extra fuel as one of the precautions. We have verified that on the DynoLog chassis dyno via the wideband O2 sensor. Up top the mixture went rich, and then a corresponding power drop.

I posted the below thoughts on a couple of related threads, and have repeated it here for the benefit of those who might miss it...

I have been thinking (maybe that is a bad idea :eek: ) They (Mazda) say the only way to measure engine power is on an engine dyno. That part is correct. But on an engine dyno you still need your ECU hooked up, as it is what is controlling what is going on... So what about the wheels turning etc... when they are not even there? Then it hit me like a light bulb. Are you thinking what I'm thinking???

Instead of fooling the computer to think the front wheels are going the same speed at the rear wheels - why not disconnect the rear wheel sensors, and make the computer think the rear wheels are going the same speed as the front - 0 RPM???

Worthy of injecting into the discussion I think!

Cheers,
Hymee.

Mr 350Z Driver, thank you for your charming and constructive response. You are certainly doing a beautiful job of contributing to this community.

Based on this response of yours I have to conclude that you either (a) do not understand the issue, or (b) are deliberately trying to start a flame war by making inflamatory statements. If the former, let me explain the implications of this again:

(Do burnout to get best 0-60 or 1/4 time) = (Car goes into limp mode)
(Limp mode) = (Drastically reduced power output of the engine)
(Drastically reduced power output of the engine) = (poorer 0-60 or 1/4 time)

Your statement that the car is a high 14's car is based on what? What you read on the internet? What someone else told you? The car magazines test results? Or even more credible, actually seeing slip times at a race event? REGARDLESS, all of these tests would have been done with the car in limp mode, and the resulting retarded power! Without limp mode, the power would have higher and the times better.

Get it now?

On the other hand, if you are indeed trying to start a flame war, that will soon become obvious and will be dealt with accordingly. Consider yourself warned. Or you can just save us all a lot of trouble and let me know right now.

Thanks...

Good thought, but as I recall, Canzoomer tried this first but it reported error state and and threw a CEL. He had to connect the sensors together to bypass this problem.

I have seen 3 RX8's run at my local track in near ideal conditions, traction control fully off and they concider themself good drivers and not seen 1 do better then a 15.18@93mph with a 2.11 60' in a combined 8+ races watched.

Thats a far far cry from a 14.5, people spend hundreds and sometimes thousands to get .7 in the 1/4. And this is with a 2.11 60' so its not a launching error..

I am actually giving the benefit of the doubt saying high 14's, given a perfect launch and a near a near perfect 2.0 ish 60' its attainable.

And the limp mode theory when doing burnouts etc just makes me laugh. Looks to me llike you people are reaching for anything that resembles hope.

...and that means what?? who doesn't consider themselves a good driver, be they good or not?? obviously no one who actually drives would want to admit that they're not very good, especially those who take so much pride in their car that they take it to the track adn try to perform...

I am a good driver! ;)

guys, there no point trying to reason with 350Z. He thinks he is an expert on the 8? The Z is a nice car, but I don't think I would spend any time over on their site just to bash?
With a simple ECU mod (Canzoomers stage 1), I am sure you will see the 8 put down some great times! Might surprise a few Z drives out there.