Prop selection issues
 

Hey anyone who can offer advise! I have a 1994 wellcraft scarab 29. It has the 502 mag/bravo one combo. I scrapped the EFI and went carburetor. Added aluminum heads, Imco power thumper exhaust, aluminum intake, and carb, and mild cam. Im running a merc rev4 propeller. Its a 21 pitch. I like the bow lift it gives over a bravo one. My problem now is im turning 5400 rpms at 58 on gps. Need more speed. What pitch should i try? Any guesses as to how many mph gain with correct prop? Thanks

Without supplying anything information about your engine build there really is no idea the power it makes and where it makes that power. You might be optimal right now.

I just figured 5400 rpm for a big block is a little to high. I was thinking about trying a 24 pitch rev4 to get rpms down to 5k and hopefully gain a few mph? Anyone agree? Never had it dyno’d. Not sure of exact HP.

It really does depend on where the engine is making peak power. If the engine doesn't make power over 5400 rpm, then no reason to spin it that high. If you have a good valve train those RPMs aren't out of the question IMO.

What cam ?
mild is not a cam part #

Borrow a 23p Mirage plus. They are tons of those around. What area are you in?
Chris

I had a mirage plus. Not enough bow lift.

If you want to go faster prop test. I read you said the Mirage is not giving you bow lift, borrow a 23” Mirage and try it;(I assume you had a 21”), try the 24” Bravo. There are vendors who allow returns*.https://hydromotive.com/policies/

or call a prop company like Hydomotive and get an opinion from the experts, or reach out to Mercury Racing https://www.mercuryracing.com/contact-us-propeller.html

I have never ran a Rev 4, you know your boat best, but if it were me I would get three different props and start testing (I used to test props routinely). I get you want that extra few mph.

I think you may be successful, it takes time and money.

REV 4 is a great prop for your application. Essentially, you're going to need more power.

Thanks everyone for the advise. Will do