I'm trying to figure out my power at the crank. If I have 135rwhp and 117rwtq, what is that at the crank? Anyone know the driveline loss %?

 

Driveline loss is 15% regardless of HP/TQ.
See my post in the "Proof of HP" thread. There is a totally stock run there. Mazda advertised 182 (bhp), the car ran 156 rwhp. That's within 2hp of the 15% factor.
All best,
s
webmaster@dynolab.net

 

there is no exact %, depends on how much you are making, as well as the condition of tranny, rear end etc. but a normal powered rear drive car should be between 15-20%.

 

Percentage lost due to drivetrain losses is in fact completely dependent on the power you put out. As a car makes more power its drivetrain losses as a percentage of the total decrease. You're always losing more power but just the percentage gets smaller. This means that the average NA is probably losing about 20% (from my dyno experiance) while higher horsepower cars come closer to the 15%. In extreme cases losses can go as low as 10-11% with huge power numbers.
-Matt