Big spinners are Good when considering the aerodynamics of the prop, and the aerodynamics of the cowl/fuselage, but they make cooling difficult. If you look at modern full size planes with large spinners they either have cooling inlets that are very far out to the sides like a lancair... or they have an anular inlet around the bottom half of the spinner like Sean Tuckers Pitts, or the new aerobatic airplane called the Chanute.
Ty