WOT at 5,000 rpms

[JJags3]

I have a 20' Aquasport with a Johnson 112. The motor is tuned, hull is clean, bilge is dry, usually about 25 gals. of fuel and some fishing gear. Yesterday I ran it for about a mile WOT and the tach set dead on 5,000 rpms.

The motor is set on the transom as it was setup from the dealer. It has a three blade aluminum prop, 14.25 x 17 pitch. The Smart tabs get it up on a plane quickly and she runs nice and level.

My question: Do you advise that I try a 15 pitch to get the rpms up around 5,500 or should I be satisfied as it is now. One other thing. I rarely run WOT, usually cruise around 4,000 or so.

Thanks

 

[steelespike]

Re: WOT at 5,000 rpms

Any figures on speed?Try to get a gps and give us the speed without it 5,000 rpm doesn't mean much. I would suggest you check your setup first.
Carefully adjust your trim.
Then with the antivent plate(just above the prop) even with the bottom of the boat raise it a hole at a time to a point just before venting becomes a problem.Be sure it pumps water.
This could gain a couple of mph and some rpm Then you can decide if a prop change is necessary.

 

[Fireman431]

Re: WOT at 5,000 rpms

What is the manufacturers recommended WOT? Say (just for grins) it is 5000-5400, then you would want to trim or adjust pitch to be within that range. Going down in pitch from a 17 to a 15 will raise WOT approx 400 RPM. But, if that puts you over the range, you're asking for trouble due to over-revving.

 

[JJags3]

Re: WOT at 5,000 rpms

The anti-cavitation plate is already an inch above the hull bottom. I would hesitate moving it up higher. It already cavitates slightly on a sharp turn. I do adjust the trim when I am running WOT and that is what gets me to 5,000. My owners manual says the Full Throttle Operating Range is 4500 to 5500. I think at this point, until I get a GPS and check the speed, I'll leave it be.

 

[steelespike]

Re: WOT at 5,000 rpms

I would say your setup pretty good. let her ride for now.