The Webra P-5 that was mentioned above is a compact, "dense" engine in that it is physically small yet has a lot of meat in it. It is designed to turn props from 14x12 to 16x8 at sub 8,000 to 8,500 rpm. It is built strong and in my mind has the extra mass to handle the heat. It is a very smooth running engine and has a very cool purr when doing its best work.