I use this engine a lot in my research project. at last count, I think there are 16 of these engines on research planes of all sorts. I use the Master airscrew classic composite prop. If you want to pull heavy loads, the 18 x 8 prop is the prop of choice. On the ground, the engine will tach between 7800 and 8000 rpms. When loaded pulling a heavy load in the air, the engine turns in the mid 7000 rpms which is at the peak of the torque curve. If you are sport flying, the 18 x 10 is the prop of choice. The engine should tach in the low 7000s on the ground and unload to the mid 7000s in the air at the peak of the torque curve.

I think these are good props and I wish MAS would make them in sizes larger than 20 inch.

I hope this helps

Elson