- Sep 17, 2008
You're off some. The worst aircraft engine turns about 25% of the fuel's energy into useful power, or more than twice what you say. It's still pretty sick. Another 25% is lost through cooling, and 50% goes out the exhaust, some of which is often saved by turbocharging. A EFI/EI ICE would get a lot better than 25% just through more efficient ignition and modulating of the mixture to the best efficiency at all times.This comes up all the time. So if gasoline has about 33.6 kWh/gal, this is about 12.4 kWh/kg. A typically AC ICE engine uses only about 12% of that.