Originally Posted by
Frank Giger
Top View, you've got to ask a better question.
I'm guessing that English is a second language - and that you are excellent in it - but it is hard understanding exactly what you want to know.
For air cooled engines, like the VW (my 1915cc VW is around 90 HP) or the Corvair (about 120 HP, making it a good alternative to an O-200), they work about the same as certified engines.
For liquid cooled automotive engines, I'll defer to others. But in the end it always comes down to how the builder runs the cooling. Some are better than others. But it is always about airflow, whether over the cylinders and oil cooler in an air cooled engine or a radiator in a liquid cooled one.
My comment about helicopter rotors was a joke, btw. I often refer to my engine as the "loud fan up front."