Prop Question?

[birdswacker]

I have a 1996 Johnson 88hp the prop numbers are 14x17. I know the pitch is 17 which pulls the boat out of the water? What the 14 number? Looking at getting a new prop as lake coditions are low. The one I found is a 13.25x17 what differences will this make compared to the 14x17?

[PerchJerker]

I think the 14 and 13.25 numbers indicate the props diameter. A smaller diameter prop is going to spin faster and raise your rpms (all other things being equal).

[birdswacker]

What RPM should I be running then?

[marine_man]

Max RPM (or, where you want it to run) is 5500 RPM. Where are you at with respect to that? That would be at the max performance - trimmed out just before it porposises at full throttle.

marine_man

[birdswacker]

Motors running at 5000rpm and 43mph. Looked all over the motor to see if I could find a tag or something for max rpm but can't find one. Is 5500rpm just a rule of thumb or should I be talking to a johnson service guy to find the max?

[marine_man]

You won't find a tag on this motor for Max RPM. I believe Mercury is the only one who puts max rpm on the engine s/n tag.

There is no rule of thumb for max rpm on a motor.. they all vary depending on the make, hp, etc. I believe the range is actually 5000-5500 RPM on your motor, but for best performance you're best off around 5500 RPM.

marine_man