Quote:
Originally Posted by Frank Lee
Don't be fooled about "engine speed" by only looking at crankshaft rpms:
Most powerful diesel in the world: 98" stroke at 102 rpm = 1,666 ft/mn piston speed
Honda 50cc Super Cub at max fuel efficiency speed: 1.63" stroke at 4300 rpm = 1,168 ft/mn piston speed.
Hmmmm.
Yes one is a supercharged two-stroke diesel and one is a four stroke gasser. Different engine types seem to have different piston speed ranges for max fuel efficiency.
You can easily drop off the bottom end of the engine's efficiency zone by doing that.
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FWIW, that is AVERAGE piston speed. If you look at the PEAK piston speeds, you might find some interesting results.
But to do that, you must do a bit of math and know the Rod length and stroke.