Vince,

Where can I download the second run file. I need to see the
uncorrected numbers.

I'll email them to you.

Vince

Please send it to Nashua_Night_Hawk@yahoo.com

Thanks.

Looking at the dyno closely, thre is 10 lbsft drops at 6400rpms and another 10 lbsft 7400 rpms.


Why there is such restriction? is it no enouh intake charge?

Can one tune the intake to make the curve flat and peak 125 lbft at 7500rpms?

Nashua

Sent.

Vince

Not a restriction, just a set of ports opening causing a change of airflow. It's a good thing.

Vince

can someone explain why the data uses 7600 rpm?

the red line goes to almost 200 at higher rpm, why's max hp 187?
torque is going down on the chart at 7600 rpm also, why pick that point?
i guess my question is how to interprate the chart

There is a clear evidence that that timing is being pulled back at the higher rpms (jaggieness in the curve). That is due to detonations and low octane. Also, the A/F is richer than that on my CLS. So, lack of more O2.

SAE correction is 1.0 or 1.01.. It was hi temp, low Humidity and the Atom Presurre at 29.8-29.9"

I think with Higher octance and colder weather.. the RX-8 can gain as much 10 WHP.

Nashua.

Guys,
Through some research and talking to a few folks, I can speculate with high degree of certainty, that the RX-8 is pulling back some timing and adding fuel up high, to protect the engine while on a chassis dyno. This among other things. If my understanding of the matter is correct, the sophisticated 32-bit ECU collects data from several inputs to implement the operational fuel and timing maps. It seems that some of the inputs that the ECU is receiving, while on a dyno, is telling it something is not absolutely correct, and that it should use, what I would term, safe maps.

I have not been able to absolutely confirm all of this information, but it seems to be a very plausible explanation for the descripency between 1/4 times and dyno results.

Also, and very important to this discussion, should be the proper SAE correction factors. As Nashua is properly trying to do above. I've seen quite few dyno plots with correction factors all over the place, if any at all.

The search continues.....

-Bern

Nashua, the jaggedness cannot be detonation, detonations + rotary = no more rotary, and wankels are highly detonation resistant, it is more likley misfire. Alsoi agree with the explanation of the cpu not liking the dyno, the maps are definatly "safe" maps based on the afr's, someone should check the ignition timming while on the dyno somehow.

If the ECU only goes rich on a dyno, then why do non dyno'd cars have that sooty exhaust (which stains everything instantly- oops, won't be sticking my finger in tailpipes again)?

The little jaggies on the dyno plot are because of the longer time spent in the zone allowing for more samples.

Vince

I think you may be on to something here. When driving my car (800 miles) in 1st or 2nd to the redline, I feel (I know "butt dyno")a definite kick about 6250 rpm and another slightly sofet kicj around 7500 rpm, but it's definitely there. It's almost scarey at first, like a small turbo kick but absolutely controllable.:D

The guessing continues...

Vince

No guessing. Berny is correct...

These cars can't be dynoed. and obtain the same results as street driving (with the US ECU program)


See me at SevenStock for info on why :D Here's a hint though, the federal government is to blame

You don't have to rely totally on a butt dyno. I've hand timed my car from 5k-7k and 7k-9k on the tach in second gear. The car is always about a tenth slower in the RPM higher range. I too feel the kick, but in realilty it's following a decrease in acceleration just prior to the kick.

Another thing I've notice is that the digital speed display has a lot of latency in it. If you hand time acceleration runs vs. the equivalent tach reading rather than speed display you get a better answer. Hand timing is very innacurate from a standing start becuase you don't know when the car starts moving vs. clutch release and traction is the primary influence. It's much better at rolling starts (+/-.1sec). My car is doing consistent 5-60 runs in 7.3 sec which is better than C&D @7.5. Also 70-90 in third comes much quicker than the 4.8 sec that R&T reported.

Try it yourself.

Also, I think heat has been to little talked about as a reason for performance degradation. A car that is rated at 238hp at 75F will only put out 229hp at 95F just because of changes in air density. I'm noticing that performance is getting alot better as the temperatures drop which is consistent with my other cars as well.

How about a link to the information?

Thanks in advance,

Vince

here ya go:
sevenstock.org

Seriously: I can't post something up yet to rotarynews.com as proof... But: re-read berny's post. Emphysis on correction factors, and with an addition of EGT readings.

Rotarynews.com
 

Thank you. That is what I was waiting to hear. Issue resolved.

Now lets pick up and move on.....and enjoy driving A GREAT CAR (if you've got one)


Is this a haiku?

cool autumn air
makes my RX-8
go faster

:D

Re: Rotarynews.com
 

No, a haiku must have 5-7-5 syllables. Try this one:

Mazda RX-8:
Dyno says it is a dog,
but we know better.

:D

This sounds like bullshit to me.

Let me get this straight. Someone's brother Billie-Bob gets some unverifiable information from someone they can't mention and we are supposed to take this as gospel and move on.

Show me the proof or shut the f**k up until you have it.

If you have good information it is much appreciated (and if what was in Bern's post is verifiable it too is much appreciated). If you can't verify what you post it gets put in and then lost in crap fact hell.

So the posts from Bern and Rotarynews are in the bullshit pile until they prove it otherwise.

YMMV!

Vince

What reasons could you possibly have to doubt what Bern and Rotarynews are posting. What would they gain from lying here nothing. Some people don't have the need to post wild theories just for fun.

Well, I have to agree that its a little suspect. I want to believe rotarynews.com et al, but ... there is no actual information given. I'd really like to know whats going on since I am looking at the RX8 as a possible new car and the dyno results combined with MPG issues are a little disheartening. So ...

Is there any information you can release on this site, or to those of us interested by any means (other than an event we probably cannot attend) ?

Thanks.

Dave

PS. Any signs of weapons of mass destruction in the dyno plots :)

BEAUTIFUL!! :cool:
My ikku.
Yellow RX-8:
in the Wind
my yellow eight
like a flower.

btw:
My RX-8 is the standard type and that Power is 210ps.
I found out Dyno data about the standard type from some Japanese site.

Standard type
Max Power......127.0 kW (172.7 PS) / 8380 rpm
Max Torque....172.5 N�EM (17.6 kg�Em) / 5700 rpm
This car is having the limiter cut. An original(Normal) rev limit is 7.500 rpm.

tkanks
EAST MOON

I'm confused by this now. If the RX8 can't be dynoed, then how come Mazda used the dyno to determine the horsepower? And wouldn't it pretty much be the only car out there that can't be dynoed (which makes it seem less likely)?