Quote:
Originally Posted by richard in NC
Questions about the HP/TQ wheel vs crank.
The delta is > 20%, how do you come up with that where most say 15% difference.
Or do you measure rear wheels only and calculate the contribution from the front, given AWD?
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12-15% drivetrain loss is typical for RWD vehicles. On AWD vehicles it can be upwards of 25%. If I recall correctly it peaks at about 22% on most late model BMW's.
Those numbers are based on years of comparison testing really. In the early days we would rip out the engine and put it on our engine dyno and get numbers. Then put the engine back in the car and put it on the chassis dyno to see what kind of losses were involved. We haven't done that in a few years but you get the idea. Now with more sophisticated chassis dynos you can extrapolate even easier then in the past without ripping out an engine.