How much can 1/4" diameter diff in prop size make?

[scfan]

Thanks for all of the responses. I am going to try out the
15 1/2" diam. x 17" pitch 3 blade SSII prop. I am hoping the switch from 4 blade to 3 blade more than offsets the increase in surface area caused by the .25" increase in diameter in order to get my RPMs at WOT up to 5500 from 5200 (where it maxed out with the old 4 blade 15.25" x 18" prop. If I can't get the rpms up to 5500, the dealer has a re-conditioned 15.25" x 16" which I will then try. I will post the results. Thanks again, Charlie