I'm building a piper cub 48 and will use a RCV58CD inside a cowl.
The engine fits completely inside the cowl and I need to open up the from hole in the cowl for the engine cooling, and the air outgoing area as well.
Is there any suggested intake and outgoing area I should have as minimum for properly cooling the engine?
I thought about 2 sq in for both.
See picture below.

Thanks,

Nilo

Your exit hole needs to be about twice the size of the intake.

Thanks,
But which area should I need for the intake?

Nilo

The intake will be located in front of the cowl as shown in the picture, directly in front of the cylinder head.

I know.I mean the size of the area! How big? How many sq in?

Thanks,

Nilo

You should be able to see the majority of the cylinder head by looking through the hole. 2sq. in should be enough.

Be sure that there is no exit for the air in front of your planned exit hole(s). If there is a place for it to go out before it passes over the engine, you will not get the cooling flow you want. Good luck, Dzl

2 square inches inlet and 4 square outlet should be okay. Just be careful and watch for signs of lean running. It would also help to add baffles on each side of the inlet to move the air directly over the head.
Dennis-