Ideal WOT RPM's

[captainbob]

My 4.2L F250 with 15 1/2 x 17 prop spins up to 5500 rpms at WOT. This seems ideal to me as the engine's maximum horsepower is rated at the 5500 mark plus the recommended maximum operating rage is 5000-6000, so my 5500 is right in the middle. But numerous (non-professionals) have told me I should be trying to get 5800 or 5900 through going to a smaller prop or possibly raising the motor a bolt hole or two.

Can anyone here enlighten me??

[99yam40]

it is best to be able to run at the upper end of the RPM range with the load you are running that day. If that means you run it heavily loaded some times but light other times it may be best to have 2 different props

[captainbob]

My loading is fairly consistent on all trips, but I rarely run any near WOT. Generally cruise at 3500 to 4000 depending on sea conditions. The only place I can run WOT is inside the inlet after an offshore trip.

[99yam40]

F motors do not like to be lugged, if it starts making oil you may want to get the WOT RPMs up closer to 6K. Even if you do not run WOT, the motor should be able to get to just about 6K when you open it up to WOT