i don't think that a car engine air filter will work because i think they are too big and might get in the way of the prop. They do make air filters for airplain engines. [link]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX9158&P=0[/link] this is a Bru Line Coarse Air Cleaner. We run them on out planes because some times we are flying off the dunes at the beach.