Hello, I know that something around 65% of the potential energy stored in fuel is lossed in an engine through heat. Im trying to find exactly how its lossed, I know some is through piston friction, and some is lossed through the exhost, but I cant find how much is lossed for each. Im not an expert so let me knowwhat I get wrong here. When compressed fuel is ignited the heat makes the fuel/gas expanned. Does the (thermal or knetic?)energy from the expanding gas all get forced into driving the piston down, or is most of the energy used up pushing on the areas opposite of, and around the pistion, turning into heated metal? Is it like a rifle?. when a shot is fired half the energy goes into pushing the bullet and the other half goes into the recoil pushing the user? Minus some thermal energy into the barrel, brass caseing. Can someone breakdown exactly how much energy is lossed due to what? Thanks.