Quote:
Originally Posted by razor02097
If you want to know how much it will take to rotate the crank you could get a gauge style torque wrench and do some experimentation.
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Hmm...I didn't think that'd be useful at first, but I could take the torque measurement as a baseline of how much power it would take to keep overcoming the compression and assume I'd lose that much torque at any rpm as waste. Technically there'd be two compression strokes every 3 revolutions, and you'd probably gain back some of that energy when you pass TDC and the compressed air now pushes the piston down in favour of the direction it's rotating...bla bla bla...but I could write off that and the extra 1/3rd as estimated friction losses...
So if it took 10 ft-lbs and it took my motor 100 amps to make 10 ft/lbs, I could assume I'd be throwing away a constant 100 amps. Hmm. Maybe, maybe not. I doubt it'd take ~10hp to maintain whatever rpm I'd get at 72v. It might take that much to start it though.
I think I should just make a rough bracket to hold my motor to the engine, slap a belt around it and the crank pulley and read how many amps it's sucking down to keep the engine rotating. I'd know exactly how much I'd be wasting that way.