On my TopFlite Spitfire, I added a small ducted fan to exhaust the air out of the cowl and baffled the airflow over the cylinder. The primary intake of air is through the gap between the spinner and the front fo the cowl, which is a little wider than normal. There'smore parts, and it can be a bit fussy, but it works. Irun a small ecs which is controlled by a knop on my Futaba. I am moving over to a Spectrum radio and will be adding a thermocouple controller to run the fan. It's from Oregon Scale Aviation and was originally designed to control cowl flaps. It'll clear up a channel, and dynamically control the fan.</p>