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-   -   Prop selection for 99 353 HP500 w/boxes? (https://www.offshoreonly.com/forums/formula/231565-prop-selection-99-353-hp500-w-boxes.html)

I.D.C.E. 11-07-2015 06:15 AM

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.

Joe308 11-07-2015 07:50 AM

Brick / Barnegat bay area

I.D.C.E. 11-07-2015 09:26 AM

Cool, that's where most of us do our boating. I hope you get your boat dialed in the way you want. It is an expensive ordeal lol.

https://scontent-lga3-1.xx.fbcdn.net...50407516_o.jpg

Joe308 11-07-2015 05:07 PM

Thanks this is the truth. Maybe see you next season. Unless Santa brings me new silencer tips you will hear me before you see me. Lol.

axapowell 11-08-2015 11:52 AM

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

Joe308 11-08-2015 04:38 PM

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?

badmonkey 11-09-2015 07:12 AM

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

axapowell 11-09-2015 07:22 AM

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

racinfast002 11-09-2015 03:49 PM

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.

axapowell 11-09-2015 04:09 PM


Originally Posted by Joe308 (Post 4373594)
Brick / Barnegat bay area

Just a thought, how about Smitty at Wazzup Racing?

Dave


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