Prop selection for 99 353 HP500 w/boxes?
#21
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Joined: Jul 2010
Posts: 495
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From: Jersey Shore
Jersey is a hard spot for performance anything.... cars, trucks and especially boat propping! It is an expensive game trying yo tinker to get it just right. I know I have been paying shipping back and forth from the west coast to get my ol gal dialed in after the repower.
Where in Jersey do you boat?
Check out www.formulaownersofnewjersey.com for local happenings.
Where in Jersey do you boat?
Check out www.formulaownersofnewjersey.com for local happenings.
#25
My 1999 353 ran between 88-90 with a similar set up. Imco boxes (standard rise) -2 SportMaster shorties. 88 turning the props out and 90 turning in. Aggressive tune up with advanced timing and running lean. Safe set up was in the boat before I sold it and 86-88 all day. On the dyno, 700 corrected hp thru standard headers, with the CMI's on the dyno and running ALL accessories, a true 640 HP at the crank.
BBlades props 5 blade Mercury Maximus with the diffuser removed, started with 15 5/8" diameter cut down to a little over 15 1/4" 28 pitch everyday props. Mercury Racing 4 blade lab finished 30 pitch 15 1/4" tweaked by BBlades. Both sets, similar results on topend speed. Better cruising with the 5 blades and quicker in gear around the docks.
Engines were turning 5600-5800 RPMS Max, depending on the weather.
Lots of trial and error, lots of money spent to squeak out the last couple mph. The boat did run over 90 a couple of times with the right day. The bow will always feel low, but in reality, it is a sensory thing. Look over the side of the boat while you are running and reference where you see water on the hull sides. You might be surprised how far back that becomes while running at speed. Don't over trim based on what you think is right, take your time and let the boat settle before making trim changes, minor trim changes make pretty significant speed changes.
Good luck!
Dave
BBlades props 5 blade Mercury Maximus with the diffuser removed, started with 15 5/8" diameter cut down to a little over 15 1/4" 28 pitch everyday props. Mercury Racing 4 blade lab finished 30 pitch 15 1/4" tweaked by BBlades. Both sets, similar results on topend speed. Better cruising with the 5 blades and quicker in gear around the docks.
Engines were turning 5600-5800 RPMS Max, depending on the weather.
Lots of trial and error, lots of money spent to squeak out the last couple mph. The boat did run over 90 a couple of times with the right day. The bow will always feel low, but in reality, it is a sensory thing. Look over the side of the boat while you are running and reference where you see water on the hull sides. You might be surprised how far back that becomes while running at speed. Don't over trim based on what you think is right, take your time and let the boat settle before making trim changes, minor trim changes make pretty significant speed changes.
Good luck!
Dave
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Air, Sea, and Land...Exploring the planet in 3-D!
Air, Sea, and Land...Exploring the planet in 3-D!
#26
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Joined: Jul 2003
Posts: 268
Likes: 4
From: N.J.
Thanks for the tips Dave. Did the shorties help much? I'm set at about 4.5" now - do you know what your propshaft depth was with the std lowers? You got me by 10 cr hp on the dyno with headers but I'm running Gils in the boat and still quite a bit off your mark. We did find out at the end of the season that one of my dominators was going bad so that was not helping. May try Quickfuels next year. Were you carb or efi?
#27
https://www.youtube.com/watch?v=v1mli79565U
Here's a video of the boat running this past May with the setup that Dave mentioned.....As you can see the acceleration is awesome.......by the end of the video we are running 85MPH
#28
Carbs are Demon Marine. Shorties were good for 3-5 mph. i don't know what the finial dimension was, although I did try several spacers on the -2, it was best at -2. The boat was stock x dimentions before the boxes.
God luck,
Dave
God luck,
Dave
__________________
Air, Sea, and Land...Exploring the planet in 3-D!
Air, Sea, and Land...Exploring the planet in 3-D!
#29
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Joined: Mar 2011
Posts: 512
Likes: 1
From: Merritt Island, FL
I have a 312 with 625hp whippled motors. I am currently turning bravo 30p props on it, and on a good day, I can just bump the rev limiter. Sounds like 30p props are about as good as am I'm going to do. Don't think I have the horsepower to spin 32s.



