Scoop Plugs

Some of the foam used as packing material with electronic equipment would work. But some types is too stiff or actually styrofoam. The metal, plastic or plexiglass "facing" should be a little larger than the opening to prevent the foam from getting blown inside or too soaked. But you really should run an air cleaner at the track anyway. Stuff gets kicked up by cars in front of you and there is a considerable amount of dust in the air, not to mention when the wind kicks up! Your engine will appreciate it by lasting longer!