The debate of 2" pitch for 1" diameter VS 1" pitch for 1" diameter...

Another factor which many people don't consider is the chord width. *Usually* when diameter is increased, the chord also gets a little wider, as in the case of APC. So APC 14x8 gets about the same rpm as 15x6.

I would like to point out that APC 13" prop is a thin blade sport prop, but 14 is the pattern profile that you see up to 20". So 13x8 APC will actually get higher rpm than APC 14x6.

As for Master Airscrew nylon prop, the tip flexes under load, so a 14x6 is more like 14x6-4. You will get very good rpm with MA 14x6 on TT 91, but the pull won't be as good as APC 14x6.