Originally Posted by Old Mechanic
I checked the exhaust on my old Nissan Z car engine once. At idle it was not even 200 degrees. I think the amount of heat you need to "instantly" turn water into steam just isn't there after expansion of the combustion gasses.
I'm not sure that's right either... but drain the water from your old Z car, rendering the cooling system useless, and as the temperature continues to rise. You WILL melt the ring lands off the pistons, eventually ruin the temper of the aluminum that the head is made from and loosen the valve seats, then drop a seat and valve. The exhaust temp might be a lot hotter at idle, if your Z car didn't have a cooling system.
If in a conventional 4 stroke engine, 30% of the BTUs from a unit of gasoline are turning into work, the other 70% turned into heat, but you find a way to turn say, half of that heat into work within the combustion chamber... you have much less waste heat to get rid of. You might not need a conventional cooling system at all.