prop is too much work for engine change diam/pitch

I have a twin screw 220 hp engines and a 1-1 ratio with 15x12 federal 3 blade props boat goes good but i can tell that top end just isn't there engines seem to be working to hard should I drop my diam or pitch and how much?

 

What kind of engines and what is your top RPMs

 

v6 5000 rpm

 

I assume it is a 4.3 gas engine. The max RPM should be 4300 to 4800. You need more diameter or more pitch. Two inches of pitch should lower the RPM aobut 300 to 4700.

 

Well that will make them work harder. I think he meant rev too hard perhaps?

Mr gtt increasing pitch or diam is like going up a gear, so it will work harder in HP terms but will rev less,--like changing gear on a car --the RPM's come down.

Its possible you wont see much if any increase in speed.

Do you normally drive full power all the time?