The Mach prop is a 24P.

The motor with good exhaust would be putting out 490HP. I still have the stock exhaust on it no muffs. The stock heads were reworked to flow better.

Russ

Sounds like you are turning the RPM's but no power/torque.
What cam did the engine builder install on the 502. Nonmarine too radical for the application?
Are your speeds by speedo or GPS?
My .02 worth

How can a motor spin a 24P 4blade prop at 5100 rpms and not be making power/torque? And the speeds are GPS.

Russ how much power did the 6.2 have? How fast was she then?

The 6.2 was 320 hp. would run about 57 mph with a 19p prop at 4900 rpm's. The boat doesn't seem to come out of the water at higher speeds. You just don't seem to feel the boat lift up out of the water. Seems to ride flat. I will gain speed when I trim up but you don't feel the boat lift!

Might look into takeing the hook that's in the hull out. And finding some bravo 1 prop's.

Russ

Russ Your 6.2 was 320 at the prop your new engine is 470 at the crank. You have a 100 to 120 hp gain. this is good for a 7-9 mph gain. You seam to be in the ballpark...
Your hull may have some hook in it, causing the "wet" hull feel.

This is the engine build up. But I had it changed to a carbed setup instead of fuel injected. Edlebrock performer air gap intake and Holley 800 cfm carb. The heads where worked on more than what they did in the artical and I still have stock exhaust. Changing that out next year. They made 490 hp with the setup in the artical.

http://www.hotboat.net/members/artic.../BOLT-ON_s.htm

is it possible that the islander model is just not that fast of a hull regardless of hp??

not trying to be sarcastic, just askin

Hey I am with you I am running 393 Stroker in a 205 Four Winns Sundowner and can only get my RPM's up to 4000 Red line is 4800.
I can tell you I went to a MEr Rev4 21Pitch on a King Cobra Drive adn I am turning in 72MPH with mine.

Hey can any one tell my if thru-hull exhaust will get me more RPMS I do not want to drop pitch?

Terrible Spelling to night sorry