Originally Posted by
sjhanc
The most important fact is to have 3-4 times more cooling exhaust than intake area.
This is just not true. The most important requirement is to force cooling air through the cylinder fins. Equally important is providing a mechanism to extract the hot air, typically this is achieved with a low-pressure area outside the cooling exit location. The size of the exit opening alone is not nearly as important, and there is no magic to the often-stated 1:3-4 ratio. Using a spoiler, ramp or louvers are common ways to create a low-pressure area.
The 60cc Mustang is a challenging airplane to cool effectively but it can be done with some baffling and the exit ramp. Prior to doing this we would see occasional overheating, and frequent vapor locking after shut down.
The baffle in the image is unfinished but note that it has a 'return' to guide air beyond just the side fins. The spoiler on the cowl lip needs to be larger than shown.