I'm not familiar with your boat. Or I'm over tired. LOL. Have pics ? what's the weight ? What has your top rpm been with that prop since you have owned the boat ?

It is definitely better with less people and fuel. It weighs @5600lbs. Top rpm I've seen is 5700. Running a bravo 24 - 4 blade. Not sure how to post pics on here yet. I will if someone tells me how.

Is the Bellows for the Thru Hub Exhaust Removed?? If not, Remove it and see if that helps. seems you need to vent the prop more somehow. You have a 1.50 gear ratio?? some setups bite more than others, but a 24" 4 blade isn't usually one of them

Im gonna keep playing with it. Not sure about rhe bellows but I will check. Not sure on the ratio either.

what type of boat is this,make?i tryed looking up 1997 grand sport gs 270 and come up with nothing..if its not really a fast boat then you might need a bravo III drive..that is allot of rpm,,

Something I have ran across lately - I assumed I had a 1.5ratio drive on boat I was using to cruise around. Boat came with a 19 pitch 4 blade and was like a missle to 6000rpm (rev limit pill) I thought it was too much so I ended up putting a 26 pitch labbed hydromotive that I had as a backup prop for another boat. Midrange was awesome but it would only pull 4600rpm.(top lick)- since going through the heads this spring and making sure everything was as it should be I wanted to spin the motor much harder

Finally after several props from bblades it occurred to me I was dealing with a 1.36 ratio drive. (Stupid oversight)
Now I'm down to a 24 pitch bravo one and I'm spinning it 5100rpm. Planning on trying a 22. Hoping the extra rpm will free up some HP.

Like I said - stupid oversight but its hard to catch everything when you're dealing with someone else's creation.

Best of luck!

Fixx, there was only 3 ever made. They had a shop in Missouri and it got destroyed in a storm. Bad luck with insurance and out of business. So you wont find anything about it. Not sure if its fast or not but I've seen 78 at 5800 which tells me I should be able to pull a taller prop to drop the rpms. Ill try to post some pics tonight. Thanks for all the info guys. I found a local motor/ boat guy who's gonna see what we can find. Gonna be a couple weeks before ee can but Ill post what we come up with.

Sorry to take so long but here are a few pics.
We opened up the motor to find out it was a stock 502 bottom end with good aluminum heads that are too much for the bottom end and the cam was mild with some lobes wiped on it. The parts used were good.

The good news is should have it back together this week and on the dyno by the end of the week. Its gonna be a 565 with the same heads completely redone and a bullet cam. Hoping to see near 700hp. Hole shot shouldn't be a problem any more. Will have to play with props next.
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Glad you found out what was wrong.

Wannabe

700 hp, 5600 lb boat, stock bravo drive? after a couple of hole shots it will probably be slower than my crownline with a small block alpha...unless I blow my drive too!! then our boats will have exactly the same top speed.