On the EVO dyno graph they were running with the front wheels disengaged and they gpt 360 whp that is a 17% driveline loss. On an S2000 they got 203 hp from a stated 240 hp engine that is about a 17%-18% driveline loss. I have seen a 350Z dyno at 237 whp, a 17%-18% difference from stated hp. The figure of 17%-19% is more in line with what I have normally seen.

 

Porsche Exchange dynos more than just Turbos... they will rent to anyone... Evo, Sti, Eclipse, etc. Unlike our Turbos, some cars don't required mechanically linked drums to yield accurate readings without buring up clutch/dif packs.

The front drums didn't yield readings because the front shaft was disconnected, so the readings would be the same as RWD Dynojet.

Believe it or not, Porsche Exchange actually sat there and argued with me that it was OK to awd-dyno a Turbo, so long as you don't do too many pulls, because it'd burns up the dif... I was thinking to myself, "Are you hearing what you are saying?!?!" Of course you shouldn't do it... shouldn't be doing it in the first place. The drums are different sizes on the Dynojet, and they are obviously not mechanically linked. If the center dif were to seize, you could potentially see the car jump right off of the dyno and into the brick wall.

Stephen
'01 Turbo Ti Upsolute
1stephen1.com

 

Drivetrain loss figures being tossed around are only guestimates anyways. As long as we use the same... say 15% w/o driveshaft, and 18% with, then all else will be the same for relative analysis. If you really want to figure out the drivetrain loss, then do a coast-down on a dyno to figure out parasitic loss of the drivetrain... kind of a reverse dyno.

Also, to calculate for the correction factor, you are suppose to divide your measured power by (1.0 - correction factor). So, in my case, using a correction factor of 15%, you get:

454.9 RWHP = (454.9 / .85) crank hp = 535 Crank HP
504.8 RWtq = (504..8 / .85) crank hp = 594 Crank Tq

For you proof geeks, the correction ratio is multiplied by the crank hp to get resultant whp, therefor, to derive the crank from the whp, one must divide the whp by the correction factor to get crank. QED.

Stephen
'01 Turbo Ti Upsolute
1stephen1.com

 

The Porsche Exchange does some strange things. You are correct that EVO uses a rwd dyno, however, I think it was Stephen or Todd who indicated when disconnecting the rear drive shaft on either dyno, the correction was 1.15

Lou

 

In my most uneducated and inexperienced neophite opinion....... < 12.0:1 AFR's between 5000 & 6500 is on the lean side of safe.

Mike

 

Stephen, thanks for posting your dyno results. I'll be very happy if my Upsoluted car is achieving similar power to your car.

In terms of 1/4-time and trap speed, how do you think your car would compare to some of the cars in the shootout? From the article, 3 of the 9 cars scored less peak HP than your car, granted the 'shootout' used a different dyno to get the numbers.

 

according to PMO it is 13% correction. That is the figure used at Orbit and FVD. PMO germany also agreed they also said the only true way to test is on a Engine Dyno.

 

Going off my memory here, but iirc, the GIAC Stage II chip shoots for 12.0 at the lower RPM range at WOT (not sure if it's closed or open loop at that point), and at the upper range, settles to around 11.5.

Stephen