I cut down an APC 7x8 to about 5.45 inches for my Nova Rossi .21 that is mounted a Diamond Dust, I need to get the rpm up to about 28,000 for this engine to perform. I had one inflight propeller failure where one of the blades departed, ruined the throttle servo and loosened the engine mounts. This plane is slow to get started but is almost as fast as my Diamond Dust with a JETT FIRE 60LX and tumed pipe.