RE: Prop pitch cooling - the final word
I did not mean to get into specifics about efficiency. The subject is not about just two stroke engines, but I don't think the four stroke engines ar more then a few percent efficient thant the two stoke engines. My point is that if the energy is not being used for work than likely more of may be used to heat the metal.
I think the proper arguement to the above may be that the loss of efficiency is due to lower peak temperature, if so then the loss of efficiency is going out the exhaust. But then again the higher exhaust temp may mean the average combustion temp is higher so the metal is heated with less work output. Not sure.