Flew the P-47 Yesterday (Pictures Included)
Rckfish:
The general rule is that the cooling vent area should be twice the intake. The cowl opening should be baffled with an opening for the cylinder head. So, the exhaust vent should be twice the opening in the baffle for the cylinder head. At this time, I have not put a dummy engine on mine but I cut the opening as if I had. Plan to add one later. The best thing to do is test it. Circle around a couple of times and then land it and check to see if the engine seems too hot. I really hated to have to cut mine so I know how you feel.