Can everyone who is running a gas engine (rear carb) like my ZDZ40 please tell me how you have your engine box setup (do you have the top on it? Do you have holes drilled in the box for air? ) Also, is anyone having trouble with air not circulating properly once the plane is in the air.

I have a ZDZ40 in mine with no top on the engine box, the front of the cowl is wide open (no Cowling baffles) and the head of the engine sticks out the bottom. I think I am having air supply problems especially in the air and I'm wondering what setup other people have.

Thanks ahead of time for any help on this.