Quote:
Originally Posted by Zaggeron
Ahh, so when I see more than 15% loss it's likely because the at-the-crank HP was overstated.
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Yeah typically but of course some drive trains will be slightly more / less efficient than others.
As long as the WHP accounts for no more than ~ 15% loss of peak output for RWD the chances are the motor is making its advertised horse power.
So for a 200hp RWD car such as the FR-S / BRZ it should put down ~ 170WHP. It put down 173@7000rpm so it's good to go.
A 200hp FWD car should DYNO ~ 176WHP. Civic SI's typical DYNO ~185WHP so they either have extremely efficient drive trains or the real power rating is closer to 210hp. The 2010' GTI DYNO is ~200WHP (this would translate to a 0% drive train loss which is impossible) The GTI's 2.0l Turbo in reality makes up 235hp or somewhere between 220-235hp.
A 200hp AWD car should DYNO ~ 160WHP. AWD is obviously the least efficient at transferring engine power to the wheels. This is why AWD cars are slower "at speed / no launch in the equation" compared to FWD/RWD cars of the same relative power to weight ratios.
Of course AWD cars have the advantage from a standing start but otherwise they are typically going to be slower than most FWD/RWD with the same advertised power to weight ratios from a rolling start / passing.
There's advantages / disadvantages to each drive train configuration but over all RWD is typically the most fun IMO unless you live in a really snowy / harsh climate in which case AWD is better.
Oh and automatic transmissions typically suck up more power (~ 2-5%) than manual transmissions.
And of course "peak power" is not the only thing that matters when analyzing a DYNO. You got to consider the "torque curve" how progressively the engine builds power, consistency and so on.
I'm sure most of you knew this stuff already just pointing out to those who may be confused.