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gardenman · 01-21-2010, 02:23 PM

Most efficient RPM depends on the motor. I understand some of the old fishing boat single cylinder motors were super efficient and ran at 500 RPM. But they had a big flywheel. Seems that at over 1000 RPM the piston is travelling faster than the flame front for a considerable part of the power stroke. So these old fishing boat motors were good on fuel economy but lowsey on power to weight ratio, power band and just about every other means of comparing performance.Tractor motors cams are generlly are set up to run best at 1500 RPM which is a compromise between good power band , torque and fuel economy.
In a car One would have to dramatically increase the speed of the flame / combustion process to be able to benefit from slowing down the RPM below what the optimal design RPM for the engine would be. Converting to propane and or hydrogen injection might allow for better economy at slower RPM.

01-21-2010, 02:23 PM	#1 (permalink)
gardenman EcoModding Lurker Join Date: Dec 2009 Location: New Hampshire Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	gardenman Most efficient RPM depends on the motor. I understand some of the old fishing boat single cylinder motors were super efficient and ran at 500 RPM. But they had a big flywheel. Seems that at over 1000 RPM the piston is travelling faster than the flame front for a considerable part of the power stroke. So these old fishing boat motors were good on fuel economy but lowsey on power to weight ratio, power band and just about every other means of comparing performance.Tractor motors cams are generlly are set up to run best at 1500 RPM which is a compromise between good power band , torque and fuel economy. In a car One would have to dramatically increase the speed of the flame / combustion process to be able to benefit from slowing down the RPM below what the optimal design RPM for the engine would be. Converting to propane and or hydrogen injection might allow for better economy at slower RPM.