90 Evinrude rpms...

[Lakeshore82]

I have a '88 90hp Evinrude that I bought from a second owner and I'm wondering what the rpm's should be at "top end". It's on a 16' Sylvan and at WOT I've got 6200 rpm @ 38.7 mph. It does have a mid-range shutter that I'm chasing, but otherwise it runs great. Any suggestions would be great.

 

[ob]

Re: 90 Evinrude rpms...

That's a bit high.Is that with a medium or light load in the boat? Otherwise,I'd look at increasing 1-2" in prop pitch.

 

[WillyBWright]

Re: 90 Evinrude rpms...

You don't want to exceed 5,500 RPMs. You need a steeper prop. Some people use low pitched props for better power pulling out skiers, but they need to make sure not to exceed 5500 RPMs for very long. With a steeper prop, your hole shot will suffer, but you'll get more speed. Each inch of pitch difference changes full throttle RPMs by about 200. With this in mind, you need a prop with 3 or 4 inches more pitch than the one that's on it now. There are a lot of variables, but that should get you in the ballpark. You hopefully can expect to get a bit over 40mph.

 

[Lakeshore82]

Re: 90 Evinrude rpms...

Thanks for the info. For the time being, I'll keep the rpm's down. It'll still do about 31 mph @5500 rpm's. I use this stricktly for fishin', so hole shot and top speed aren't a priority.