Originally posted by MinnFlyer
EXCAP is right, the prop should be matched to the engine, not the plane. If your engine is new, check the manual, it should tell you the recommended prop sizes. If you don't have the manual, go to the MFG website, most of them list the prop sizes there.
Actually, the prop should be matched to the engine FOR the desired performance envelope of the airplane. Your engine will have a range of prop combinations (diameter coupled with pitch)it will perform efficiently with. You need to select one that the engine "likes" and gives you the type of performance you desire for the aircraft the engine is installed on.