Change of prop size - effect on engine maximum rpm

[cmedsailor]

I just want to investigate something so here it goes:
I currently have a 3-blade 16X9 fixed propeller that loads the engine at maximum 3050rpm. If I change the propeller to 15X10 (use same type 3-blade prop) how will this affect maximum rpm of the engine? My findings (from internet) say that maximum rpm will increase by around 200 to 3250rpm but I would like your opinion too.
Thanks

 

[earlybird]

When I was sizing a prop. for my new engine, my "rule of thumb", IIRC, was that for say a one inch change of either parameter, pitch had slightly more effect than diameter.
On that basis, I'd think that your max. revs would decrease.
Have you tried prop-calc?

 

[cmedsailor]

When I was sizing a prop. for my new engine, my "rule of thumb", IIRC, was that for say a one inch change of either parameter, pitch had slightly more effect than diameter.
On that basis, I'd think that your max. revs would decrease.
Have you tried prop-calc?[/QUOTE

Well, as a matter of fact prop-calc says "one inch diameter = 2.5 inches of pitch"