changing prop size and diameter?

[88wellcraft]

Hey there. What would the pros and cons be of going from a 15 x 17 aluminum prop to a 14 x 21 stainless? 1988 omc 4.3 ltr with cobra outdrive.

Thanks

 

[tmh]

Re: changing prop size and diameter?

You'll need to give more info I'd say. That's a big change so some variables mat be tough to guess very accurately.

What are you trying to improve?
Current WOT RPM and speed with 17" pitch aluminum?

You'll significantly reduce your WOT rpm and also probably holeshot. Top speed.....depends where your performance is now.

 

[88wellcraft]

Re: changing prop size and diameter?

forgot that....18 ft open bow wellcraft.....WOT @ 4600 rpm tops out @ about 52 - 55 mph. Not really wanting to change but found a cheap one on craigslist and thought if it would be any benefit, why not.

 

[Bondo]

Re: changing prop size and diameter?

A 21" prop will be Way Too Much........

 

[88wellcraft]

Re: changing prop size and diameter?

I was kinda thinkin that...just wasn't sure if the smaller diameter would offset the pitch a little. I'll stick with what I have. Thanks for the replies

 

[tmh]

Re: changing prop size and diameter?

88welcraft, why not a 17" SS? You'd get better everything than now probably. You'd still be in/near recommended WOT RPM. High 50's mph!!!

What engine/year and outdrive ratio?

 

[88wellcraft]

Re: changing prop size and diameter?

Would an SS make that much difference? 4-6 mph?