Quote:
Originally Posted by JulianEdgar
I don't think you understand very well what is being described by throttle stop testing. We're talking changes in engine rpm of 40 or 50 rpm - basically inconsequential in terms of torque change. (And it's torque we're working with in this case, not power.)
But hey, don't take my word for it. Go and do some testing yourself, eg windows up / windows down and see if the measured drag changes matches what you'd expect in the two different configurations. Practical testing, not just theorising.
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Torque and rpm is power.
You're not accounting for the actual net amount of power derived from the fuel charge. Sure the rpm can remain steady, but that says nothing about how efficiently, or not, the engine is converting the chemo-thermo energy into mechanical energy.
A course in internal combustion and air pollution was required in my course work. We had an engine test cell with a General Electric engine dynamometer at Texas Tech. BSFC is probably the most important thing to know about an engine.
I've already told you that I did coastdown testing to SAE protocols, and top speed at the Chrysler Proving Grounds. Top speed testing at Bonneville. And General Motors Aerodynamics Laboratory helped with the data reduction.
No theorizing necessary.