Hello Cubes, thanks for the phone text.
I've had a three blade Catto on my Thorp with IO-320 for about 10 years now and have been completely happy with it. There was some consternation from a few, at the time, regarding putting a three blade on a 4 cylinder due to the "impulse cycle" as I recall.
I initially hadn't done my due diligence and hung a new metal Sensenich. Although it performed ok, I was flying out of a 1600' grass strip and didn't like having my pilots seat disappearing every time I took off! (tree's both ends). So, I started looking for a prop with a smaller diameter and better takeoff performance, hence the three blade. I spoke with Craig Catto (at the time) and he will pitch the prop to whatever parameters you're looking for and can even re-pitch if you don't like the outcome. I took about twenty pounds off the nose, better take off, a little better cruise and much smoooother. Oh and did I mention that it looks sexy!
With all that said, I now fly off of a paved strip and would probably go with a two blade Catto if I had to re-prop. Mine may be slightly over pitched, I only get about 2200 static, could probably re-pitch for even better takeoff. I cruise about 172 MPH 2400 rpm. For comparison purposes I only have the Sensenich and although I don't remember the specific numbers, I just know the Catto was an improvement for the environment in which I was flying.
I have an engine monitor and I do have to keep my "I" on #3 CHT, can start hitting 400 on warm days.
I hope this helps and all is well in the Thorp community.... great bunch.
_________________ Chuck Kincer Richmond, Me 575CK KIWI
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