Based on the dyno charts that some have posted, why are the results don't come close to the hp/torque numbers (240hp/153T) that are advertised for the S2000?

BTW, thanks mingster and shingles for posting earlier charts.

 

The 240/153 numbers are at the crank shaft. The numbers that are posted here are typically at the rear wheel, where there is loss through the drive train.

 

no problem... there are more to come... maybe even this weekend if I am bored. Thinking about doing a dyno on the intake.


Like Doctor J mentioned, the advertised number are at the flywheel/crank. Numbers from a Dynojet are that at the rear wheel. There you have to deal with loses in the drivetrain. I think 190-195 is a fairly common and "acceptable" number at the wheel. Some folks have stronger cars making upwards of 210... but I thinkt he average is 190-195 at the wheels.

-Shing

 

BTW, stating crankshaft hp numbers is common practice among ALL makes and models of cars.

 

Whats wrong? People have been getting measurements of 209, and with 15% drivetrain loss, do the math, (209 * 1.15 = 240) and 240 at the crank is what is advertised.

 

With a 15% drivetrain loss, does anyone know how the S2K rate with other cars in its class? Maybe the percentage number is almost the same for all cars...I don't know. But if the percentage is greater for some cars, wouldn't it be ethical for manufacturers to show both numbers. Just a thought.

 

Ill bet its alot lower than a similar RWD car. The clutch assembly is very small to begine with.

 

Historically, I think 20% is the number most commonly used (esp. on RWD cars), although modern drivetrains may be getting slightly more efficient. So a 20% loss from 240 crank HP results in 240 - 0.2*240 = 192 RWHP, which is right about what most people are seeing.

By the way, the percentage is relative to the crankshaft HP, not the drivewheel HP. That is, you can't get back to 240 by multiplying the measured RWHP by 1.2; rather, you have to divide the measured number by 0.8. So the guys who've measured 210 at the wheels might be making as much as 210/0.8=262.5 at the crank! (But more likely, their dyno's not been properly calibrated. )

John

 

[QUOTE]Originally posted by twohoos
[B]Historically, I think 20% is the number most commonly used (esp. on RWD cars), although modern drivetrains may be getting slightly more efficient.

 

Thanks everyone for your input.