rpm range

[stripersniper]

Hi all i have an older johnson 1981 150hp with vro trying to get the right prop for best performance. Dose anyone know what max rpm this engine is rated for . right now im at 5000 with trim and calm water. got a 15x17 on right now <br />any info would be usful Thanx...........

 

[rickdb1boat]

Re: rpm range

5800 with a light load on.....What kind of boat you running it on? Might need to take a look at how it's set up....

 

[stripersniper]

Re: rpm range

its on a 1975 wellcraft cc 18'

 

[OBJ]

Re: rpm range

Might want to post the model number stiper....81' didn't have VRO unless someone installed the pump on your engine. VRO's didn't make an appearance until 84'.

 

[stripersniper]

Re: rpm range

Hi all again well i made a mistake on the year of engine its a 1988 150 sorry for the confusion

 

[Dhadley]

Re: rpm range

A 15 x 17 should be fine on that boat. Play with the engine height to get as close to 5800 as possible.

 

[stripersniper]

Re: rpm range

what do you mean by engine height ? alot of people said this set up i have should go pretty good .im now wondering if its the engine and not the prop im going to take off the vro and just mix like i said it only goes to 5000rpm full trim and smoothe water ..

 

[OBJ]

Re: rpm range

Taking off the VRO won't increase your rpms striper.....listen to Dhadley. Take a look at the anti-cavitation plate...the plate right over the prop. Where is it in relation to the keel of the boat? If it's below the keel, it's too low. You want it at least an inch above to start. Will do some surprising things for performance.

 

[Solittle]

Re: rpm range

striper - Dhadley is one of our resident experts so his word is gospel.<br /><br />Engine height refers to where the engine is mounted on the transom relative to the bottom of the hull. The lower the engine is the more of the gearcase is in the water and hence the more drag that in turn sucks rpms. The rule of themb is for the cavitation plate to be 1" or more above the bottom of the hull. The best setting is determined by trial and error as the design of the hull and the characteristics of the prop come into play. You want it as high as you can get it without the intake for the water pump sucking air.<br /><br />You can pick up a bunch of rpms just by raising the engine.<br /><br />How did I do DH?

 

[OBJ]

Re: rpm range

I think you did good SoLittle......two snaps and a circle for you.......