There is a gradient of head from the inside of the cylinder to the outside of the head. Combustion creates the heat and the airflow disapates it. Has anyone measured the latent heat found when you turn off the engine? One would expect that the temperature at the surface of the cylinder head to increase after the engine stops due to no air cicrulation and the gradient averaging out. How much increase is there?

Never measured, but it's quite a bit.

Three runs hard at an autos, then shut it off, you need to wait about 20 or 30 minutes for it to cool down enough to run again....

I recall its quite a bit, we tend to leave the car running at idle for about 5 to 10 minutes to let it cool down' which is odd but true.