Look at the way a full scale lycoming or continental is baffled in a Cessna or any other cowled engine. The air is forced through the fins by sealing half of the cylinder to the incoming cool air, and then once it goes the fins, the only openings are exit(s). The cool air MUST go through the fins to be effective.
Somewhere on this site there are posts about a guy baffling an inline twin in a P-51. It is either a Comp-ARF kit or a 3W kit, I can't remember which. A mustang can be tougher to cool since the inlet is small and there isn't any outlet, scalewise.
Last edited by JeffH; 09-23-2013 at 08:07 AM.