I hope you don't think I'm weird but I never run engines in a configuration that I would not fly them.
The difference between the pictured props is way more than I would have thought. I took the ringed piston and sleeve out of a .46 engine that I converted to a .50. I installed a little used .46 ABC sleeve and piston.
Engine===Fox .46 ABC circa 1988/later lower compression head button.
Fuel=====Wildcat 2/4 10% with 18% full synth.
This engine was super rusty when I bought it from a guy out west. It has BOCA Ceramic bearings which are still glass smooth. They have only been run in Diesel conversion mode.
Exhaust==MVVS .49 sized muffler
Plug=====Ancient Fox Idle Bar
Prop=====Robbe 10x6, red in the picture
Prop=====Master Airscrew 10x6 pictured
RPM with Robbe======12,990
RPM with MA=========14,790, astounding to me and a pleasant surprise. When I fly it I will use the Robbe though, it created the most wind and the least noise.
I guess that makes it about 99 rpm less strong than the .50. With the Robbe.