Ron,


Adding holes in the cowl will not persuade the air to actually flow over the cylinder and especially over the head of your engine.

You often, surely in the case of your Extra 300, need to install elaborate baffling within the cowl, to direct the cooling air-flow where it is needed.

Look inside the cowl of any light aircraft.

You would see it appear as if parts of the cylinders are not at all exposed to cooling flow. But no. The cooling flow just comes from another direction (usually from above) and it if forced down, between the cooling fins, by snug fitting baffles.


No one would expect you to do this for your OS.50SX, but air-flow listens to no one, so having even huge intake and exhaust holes, will not make sure the ample flowing air does cool the engine... You have to make and install baffling that will see to that.