Quote:
Originally Posted by Coheed
Steady state inertial dynos are as simple and consistent as it gets. Realistically, do you really think that ANY engine is going to lose more than 25% of its power through the drivetrain? Perhaps perception should be altered to reflect that your dynos just read too low?
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If it bothers you that much, yea I think the higher reading dynos are the ones that should be "trusted". In fact, it'd be best to take the tires out of the equation too.
The mechanical efficiency of the drivetrain I read is usually around 90%, maybe a little better. Throw in tires, you have rolling resistance to deal with, and that takes off something on the order of a few percent, depending on the gear, weight distribution of car, whether or not the front wheels are spinning, etc. But you can change the type of tire, change the air pressure, and change this significantly.
IMO, you either have the rollers connected to each other and have the wheels all spinning (this simulates road conditions vaguely), or you go for the hubs if you can't directly dyno the engine. Anything in between is going to give you a number that's both further from the "truth" and not useful for determining real world conditions. But the question is, do you really need to know the number to brag?