Quote:
Originally Posted by Boss330
You can NOT have 0% drivetrain loss... A 0% drivetrain loss would mean that there is NO power required to turn the transmission, driveshaft, differential and rear wheels... That is simply not possible 
Nor have I heard of any manufacturer claiming 5% losses either. It's generally accepted that drivetrain losses usually are in the order of 10-20% depending on type of transmission etc. |
We are getting in semantics here, but tire losses and inertial factors are technically not part of drivetrain losses. IMO, true drivetrain losses of 5-12% are probably more representative of reality on modern cars. However, running a car on a chassis roller dyno, the tire rolling losses and the drivetrain inertial effects need to be factored in bringing the total discrepancy in the 12-18% range.
Quote:
Originally Posted by Boss330
If we look at a test done on a MAHA dyno, the same as used by manufacturers and test facilities here in Europe. You will see that they also display the drivetrain losses and that is as much as 120-140hp...
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Any clue on how they measure those drivetrain losses?
Quote:
Originally Posted by Boss330
The MAHA is supposedly the more accurate dyno, and is why you don't see inflated whp numbers. The dyno actually measures the losses in the drivetrain (or how much power it takes just to get it from the crank and to the rear wheels).
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Looking at pictures from Maha dynos, it seems they are roller type dynos. So the losses are more than drivetrain losses (crank to rear wheels as you stated correctly), they also include tire rolling resistance and may include inertial factors depending which type of dyno is used or what sampling methodology is used. It seems Maha does brake and inertia type dynos, the former being the more accurate one. But in terms of chassis dynos, hub dynos remain more accurate.