I had a Saito 72 break a con. rod, because of overheating. The front of the cowl was all open, and there was a large opening underneath. The engine was mounted upright, and ended up being in a dead air corner. I learned the hard way to make sure the exits are 2 to 3 times as big as the intakes, and make sure the airflow passes over the engine, not by-passing it.