The only thing I would modify to what Mark L posted is that remember to make a provision for engine movement at the end of the plenum connection to the cowling. Ed James showed me his setup on a IO 360 Lycoming making some awesome dyno tested 250HP at 10 to 1 compression. He used a tube similar to the air inlet tubes found on cars today to connect the round aluminum inlets to the glass plenum, and then the plenum was made into a U shape, and crossed the engine at the back to create the cross flow. He had 4 inch openings and reported no over heating problems. http://www.jamesaircraft.com/
No paid endorsement just another nice guy helping us aviators . Colin
