BigOLundh

iTrader: (1)

Today, I was finally able to get my car onto the dyno... Below are pics of the two pulls. You'll notice it states my car goes to 18k RPM. While this would be wonderful, the pulls were only done to 9k. So just divide all the RPM amounts by 2.

I am not sure if DSC/TCS were disabled. The person driving into the bay stalled the car. When he turned it back on... the Traction Control light was on, but not the DSC. I don't believe the systems were actually disabled. I tried holding down the button, but the the DSC light did not come on.

- I'm concerned with why it was reading so lean near the end of the band (13 A:F). When the car was tuned, it was set to 11.9 A:F. I am so ready to get a new ECU.
- The torque numbers make no sense to me. I can get virtually no grip in 1st gear... so i'm sure the 100 lb/ft of torque is very off.
- The car feels alot more linear than this power band shows. I'm actually happy with 240whp, but i would like to clean out this power curve.

What didnt make sense to me at all... is that my friends 350z dynoed 258whp today. On a second gear pull (where I allow him to punch it first)... I am usually 2 to 3 car lengths ahead of him before i have to shift to 3rd. I know i'm lighter, but that still doesnt add up to having 18 less HP????

Horsepower and Air:Fuel


Horsepower and Torque

r0tor

iTrader: (1)

HP=Torque*RPM/5252

...so if the horsepower looks correct (and it does) and the rpms are 2x what they should be (and are), then the torque is 1/2 of what it should be (and is)

TeamRX8

iTrader: (25)

I suppose you can't expect much for $10/run, glad I decided not to go

ps: those images are too big, you should minimize them by 50% at least

BigOLundh

iTrader: (1)

Holy F... thanks man.
So my torque reading came out to 208 lbs/ft

THANKS!!!

TeamRX8

iTrader: (25)

well maybe, we're kind of guessing, it makes me wonder what else wasn't setup right

BigOLundh

iTrader: (1)

Using the peak torque values of
145 HP and 7300 RPM... it comes to 104 lbs/ft
at
145 HP and 3650 RPM... it comes to 208 lbs/ft

But your right... i dont think i'll go back to that place for dyno pulls.

r0tor

iTrader: (1)

i concur on all 3 points

TeamRX8

iTrader: (25)

except you really don't know if they put in any of the other factors correctly, the whole thing could be off, you may be trying to make sense out of something that doesn't really make sense, it's hard to say ...

Ajax

You have to remember 2 things:
1. The Z isnt just heavier, it's heavier than the 8 by 300lbs or so. That's a lot of weight!

2. The Z's redline is 6000-6500RPM (i don't remember. it's been 2 years since I drove one) and ours is 8500 (9250 comfortably). Which means horsepower considered, you're going to be going faster respectively in 2nd gear than he will and he is going to hit the top of the gear before you will and have to shift earlier.

What you should do is swap cars and you'll totally understand. The longer you keep the car in gear though, the faster you're going to go.

TeamRX8

iTrader: (25)

the real reason I decided not to go is because I want to use the same shop for all the before's and after's, they may do a good job under normal circumstances, but $20 for two runs is probably not going to get you the best service

so, did you at least get a couple of hotdogs out of the deal

therm8

This is the same reason S2000s can run with Z's. Lot's of gearing and weight advantage.

Plus that torque curve looks very nice. Lot's of it available very early, and it never really goes away.

btw: those files are HUGE

Hymee

iTrader: (1)

Let me say that unless you have a baseline on the same dyno, then the "results" don't mean a real lot other than Dyno Queen numbers.

You really need to be able to compare before and after numbers on the same dyno for the numbers to tell a better story.

Cheers,
Hymee.

BigOLundh

iTrader: (1)

I agree... but ideally that would be the same dyno, under the same conditions (weather, etc)... which is very hard to do on a project that takes over 6 months. I'm not trying to compare this to my stock system. I'm just satisfied with where I am now.

As i'm sure you know... having a gagillion HP doesnt mean a whole lot if you can't take advantage of it. Hopefully next season i'll be able to handle the power.

Thanks for chiming in. Big Fan

-HS

BigOLundh

iTrader: (1)

Hell yeah i did. 2 hot dogs, 1 BBQ Sandwhich and 3 cokes...

BTW, it was only $15 because i signed up for the DFWCarClub last night.

TeamRX8

iTrader: (25)

cool, sounds like you had a good time

even though the results may be questionable there's no doubt your RX-8 is making some good power

btw, did your Z buddy have the same issue with his graphs?

Fanman

The 204 lb.ft. of tq sounds right for the turbo pulls with about 240 whp. That is about the average pull of most Greddy turboed cars (240 whp, & 200-205 lb.ft. of tq).

BigOLundh

iTrader: (1)

He said the RPM levels were correct. I looked at a few of the graphs from the G35 owners that were there. Theirs were correct as well.

therm8

Just the wrong signal pickup point for yours I suspect

BigOLundh

iTrader: (1)

Oh, i left out the best part of all this.
One of the mechanics was standing there, and im like "why is my torque just 108, when a stock RX-8 puts out close to 159"
He says it was because these numbers for torque are "at the wheel".

I didnt feel like arguing so i just ate another hot dog.

Hymee

iTrader: (1)

I'd say that the torque number is "corrected" for roller RPM v's engine RPM, since both are known in this case. (Well, sort of known - if the timing sensor was correct) I believe this is common practice for mass/inertia dyno's such as the dynojet.

If it was really about 200 "at the wheel", and assuming the car was in 5th gear (for 1:1 in the 'box), then the torque at the flywheel would be 45 lb.ft (200/4.444) which is way lower than 159!!! So that obviously is not correct. The torque lost through the drivetrain is only about 25%, as a very rough guide.

Btw - 5th gear would make the roller speed too high anyway, so I suspect it is a lower gear anyway.

So if the figures did take into account the final drive ratio, and adjusted for the correct RPM, then the theory holds water compared to Fanman's figures. You are making about 44 ft.lb more torque, or about 30%.

Cheers,
Hymee.

RX8-TX

eehh.....Jon, c'mon! The Z's gearing is set to hit the exact same speed we do in 2nd gear....I believe! So, no...

Actually, the fact that a Z may have to shift earlier is accurate. Not because they are struggling to pick up pace but, because they get there -62mph- faster than we do. You should bum a ride with Luke.

TeamRX8

iTrader: (25)

no, a 350Z is 7 or 8 mph less than an RX-8 on the redline in 2nd gear and it was a running start against a turbocharged RX-8, not a stock one.

RX8-TX

That was pretty close actually. Depends on where the actual redlines are:

BTW, thats on a track edition -only gearing info I could muster quickly. Still, not a tremendous difference.

Rotary Rasp

iTrader: (2)

Maybe not a big difference, but it is still about 5 - 7 mph faster dependong on how hard you push the car.

BigOLundh

iTrader: (1)

I edited the size of the pics. They're just 210kb now (versus the 2mb before)

If your interested, below is the dyno chart from the Z...