poco242..... I'll bet it sounds great. Being able to fly inverted is not reall all that critical. It would be a perfect engine for something like Spads et that have their engines mounted lower on the fuselage. I'll bet it won't be logn before the "inverted" problem will be worked out with four strokes. And, you can bet that Berillelli will be at the forefront. Keep us posted on your build. Bob