13 out 20. I have to argue the how are small engines cooled question though. Petroleum air or electricity....true they are air cooled but the first method of cooling is the induction of the cool fuel /air mixture into the cylinder. kind of a trick question if you ask me.
I have to question how hot an engine gets. 4500 degrees might be the temp of the flame kernal but not the cylinder, piston, rod ,crank, carb or any other part of the system. Steel melts at about half that temp never mind aluminum .