Hi everybody,

Wow, I never expected to get this much of a response. First, to Minnflyer, the prop size according to engine size is just that, a quick and nasty rule of thumb. As I said, individual mileage may vary. It really does depend on the plane and flying type. I would prop a Sig Hog Biplane differently than I would a Venus or a Patriot, even if they had the same engine size. I also see your point about the oil being the same no matter what (I had a dumb moment there). Oil is the same through out since it doesn't burn (as long as I am not running the engine too lean). If anything, I am probably wasting fuel more than anything else. Also, running the engine at 11.5k rpms is not going to damage the engine. It is running well into 2 stroke performance, not like a rich break-in "four stroking" performance which in my opinion can cause more damage. I also agree that the best determination for the correct prop is to test out several different sizes and pitches and choice the one you are most happy with. Now, I do not pretend to be a "Know it all." I throw my statements out there for more learned and experience people here to read and correct me when needed by sharing their experiences. Believe me, I have learned a lot in two years, and by reading these forums, I have the collective wisdom of many years of experience. I will probably slowly increase the rpms on the P51 until I get to a point where I am satisfied with the performance. I will do it slowly and responsibly. I will probably stop around 13.5k rpms (unless it seems that the engine is too lean) and switch to a different prop pitch or size (11x6 or 12x5).

Happy flying and soft landings!

ser00