Sorry akpilot, but a larger cowling will give you more drag due to the increased frontal area and wetted area.

Hey Someone11, where do you fly? I live in Fresno also (Clovis actually) and I usually borrow Buchanen's fields for my gliders or a farmyard for my little electrostreak. Anyways, most spinners I've seen are smaller then the engine's cowling, so I wouldn't worry about it.

Dan Nelson