[M Colt]

I have a 90hp 4 stroke on an 1860. Goes right around 38-39 with 3 guys and gear. Has 17p on it now, what prop can I spin to get few more mph?

 

[Rock213]

what rpms are you running at WOT? I also have a 90 4-stroke on my 1972. With a 19-K aluminum prop I am turning about 5700 rpms which is pretty close to where you want it to be.

 

[M Colt]

I don't have a tach installed. Just feel like motor has more in it

 

[Kajun]

It's an expensive trial and error game w/o knowing the RPMS at WOT. Unless u have a contact with a prop shop that will let u borrow different sizes to try out.

 

[Rock213]

Like Kajun said that could get expensive unless you have someone that can let you test different props. Just be careful when you start going up in pitch. You will lose hole-shot but will pick up top end speed. You will get aggrevated when it takes a footfball field to get your boat on plane just to pick up a couple of mph on top end. You want a prop that does both, gets your boat out of the hole quick and turns your motor around 5.5-6k rpms. I always like to keep my boats around 5500 rpms at WOT

 

[M Colt]

I agree, I never go above 5500 on my previous rigs. I'll get a tach installed. This 17 gets on plane really quickly but I'd like to be around 45 mph