ilikemy944

243tq at the wheels minus 15% drivetrain loss = 206tq

Rogue_Ant

Ah yes, I forgot about the Nm-Tq conversion.
From factory the car is rated at the flywheel. Drivetrain loss is expected, so the rear-wheel-hp will be less.

And if you are on stock turbo - then I think you have a pre-turbo exhaust leak causing the slow-spool up.


-Rogue

catamax944

Unfortunately no.....It ran 204tq at flywheel and 178tq at the wheels
I know its rated at the flywheel and since now i have been talking about flywheel hp,no confusion,rear wheel hp is 191hp
Yeah,the turbo is stock as well as everything else but wouldn't an exhaust leak be easily noticeable?

Rogue_Ant

The dyno is converted for FWHP?

An exhaust leak you should be able to hear, might not be able to see easy though if it is under the shields.
A couple of other options is that the crossover pipe has collapsed; the downpipe has collapsed, or the factory wastegate isn't sealing properly. All these will cause slow-spool and loss of power.


-Rogue

catamax944

I dont know if the dyno is converted for FWHP or if the data was converted after.Just look at the dyno sheet ,potenza motore=engine power , copia max=max torque and potenza ruote max=max wheel hp .

Ok everything will be checked and i'll let you know how it turns out.

ps:the guy at the dyno said that the piston rings might be kaput and the engine is losing compression but i think that is very unlikely.
What do you think?

Rogue_Ant

If the rings are that bad, then it would be burning quite a bit of oil. I doubt the rings are the problem. I think it is one of the things I mentioned earlier.


-Rogue

V2Rocket

+1 on WG

on another note i heard something sad the other day, a corvette ZR1 dynoed at like 505WHP versus 640 at the crank, thats about 50 off of what I would expect, unless the 640HP number is not accounting for supercharger drive loss.

StraightSix

I'd be really surprised by that. I would presume that Chevrolet is coming up with a flywheel horsepower number from an engine dyno which would inherently account for parasitic loss from the supercharger.

Another thing to consider regarding the ZR1 dyno number you heard is that there's no mention of the brand of chassis dyno being used. IIRC, the Dyno Dynamics chassis dyno reads much lower than a Dynojet.

INURGRL951

Wow that low for the ZR1 spencer have there been others that have dynoed that low also?

hacker-pschorr

What kind of dyno & what correction factor?

On a Superflow Dyno alone you have four different correction factors that can easily swing 50+hp between the two extreme numbers.

Also, dyno's like Mustang and Superflow have operator adjustable parameters that can produce some very wild numbers if setup incorrectly (or "tweeked" to produce better numbers).

Reason why (for the most part) dyno's should be used to compare changes before / after. Not to compare absolute numbers from different cars at different dyno's.

V2Rocket

i dunno what dyno, it was on a car review video thing comparing the ZR1 to the GTR

hacker-pschorr

http://www.autoblog.com/2008/09/24/c...d-at-535-rwhp/

V2Rocket

oh ok

333pg333

So that Pizza Cavalli is to be avoided?

333pg333

Our local Porsche club uses a ratio of 1.32 when calculating drivetrain loss, not 15%. I thought that was excessive but they maintain that it's in line with the Factory?