225 Oceanrunner prop pitch and WOT RPM

[Rogue I]

I have a 1997 225 Rude that was rebuilt this past winter (new wisco pistons, etc etc). I followed break-in to a tee, and the engine runs great!

I have a 1978 23' Mako with 19 degress of deadrise. Current prop is 15x17. Hull should weigh apr. 2500lbs (hull only). With about 50 gallons of fuel, myself (200 lbs) and of course the 480lb Evinrude, I can only push 5300rpms for 32mph or so. So, I moved down to a 15.5x15, and can get about 5500-5600rpm and 34mph.

My questions: 1) Dont I want to be hitting more like 5700-5800 at WOT (I rarely run it there btw)? Should I move down in pitch? Is the engine mounted too low?

2) Isnt 34mph for WOT a bit slow? It runs at like 26mph at 4200rpm.

THanks for all your help. If the 15.5x15 is the wrong setup, I need to know soon so I can take it off and return it

 

[wilde1j]

Re: 225 Oceanrunner prop pitch and WOT RPM

That motor should turn ~ 5800 @ WOT. Not sure you can get a lower pitch stock prop. Are you sure everything else has been optimized? i.e. "x" dimension, tried trimming out as much
as possible w/o the boat getting too loose, etc?

 

[steelespike]

Re: 225 Oceanrunner prop pitch and WOT RPM

Not an expert but I believe your motor developes its horsepower at 5,500 RPM.Have you run it through a breakin period? I figure your pushing about 3,600 lbs.
sounds like a good chunk to me.Probably more if you consider battery,top(?) Bumpers and misc. gear.
You could sure try to raise thec motor one hole and see what happens.Watch the cooling.
If you can gain an inch you could get 2 to 3 MPH and 1 or 2 hundred RPM.
You should also post this question at the prop forum.

 

[Rogue I]

Re: 225 Oceanrunner prop pitch and WOT RPM

I do have a t-top, and the motor is definitely trimmed up a fair amount. It has been broken in yes.

How hard is it to raise the motor a hole?? Watch the cooling in what way? So I am right that I should be seeing 5800 huh??

 

[Dhadley]

Re: 225 Oceanrunner prop pitch and WOT RPM

If you can use 90-100% of the trim range, most likely the motor is too low. Try moving it up some. What we're saying about the cooling is to watch the water pressure. You have the baseline numbers now, just watch the pressure as you go up. That gearcase should have no problem picking up water mounted on the transom (no jackplate).

Look for 6000 rpm with an average load.

 

[Rogue I]

Re: 225 Oceanrunner prop pitch and WOT RPM

I can raise the motor one more hole on the mount, and that's it. Should I go ahead and do that?

Anything else I can do?