my bravo outdrive gear experiment

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09-18-2006, 08:16 AM

#111

articfriends

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Re: my bravo outdrive gear experiment

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Originally Posted by rmbuilder

Smitty,
Did any of the treated components fail or was it collateral pieces? I have additional info on the short run gear-sets we spoke of.
Bob

Bob,drive broke last night on the bay on our way in at sunset,won't know what broke until I get some paying work done and can get back to it in a few days but I'm thinking vert shaft. Prop spins effortlessly with no real noise,if gears blew teeth you would feel some serious crunching/binding as you spun it,Smitty

09-18-2006, 08:22 AM

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zt260

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Re: my bravo outdrive gear experiment

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Originally Posted by articfriends

Borrowed a 28 pitch 5blade maximus this week from a fellow oso'er,tried it fri night back to back on the river against my 30 pitch labbed w/ext box w/1" spacer. Incredible cruise but slower on top end by 1 mph and lagged accelerating above 5000rpm's,also tq steered to port even wide open which boat has never done. Drained oil from lower yesterday,no metal from lower gears yet since newest treatment (cryo/isorem) even after some very long passes at hardy pond last week plus the testing fri and a couple of weekends of boating too. Pulled lower from upper,removed spacer and studs this morning putting lower back up to 1" raised position to try with 28 5 blade before returning it. Took boat out today,pulled fairly well with 5 blade even with heavy load in boat except still takes 10-20 seconds to go from 5000 to 5700. I made a half dozen high speed passes ,was heading in and leaned on it one more time,brought it up to 5000 fairly easy,started leaning on it with throttle to the wood and sheared something off in the drive

. I have put 5 or 6 sets of gears in lower after they started breaking thru the hardness but haven't blown up or sheared any gears or shafts in the past 3 seasons. Either something was fatiguing or the 5 blade just pushed something past its limit,we'll see in the next few days,I think a 5 blade is just too hard on my drive with the kind of torque I'm making,Smitty

A stock 30"bravo is really about 29" I realize it’s labbed, but it’s good you could turn the 28" Maximus. What RPMs do you normally turn with the bravo?

What were the slip numbers like? You can almost always raise the drive 1" or more and have better numbers with the Maximus's diameter. Also how about WOT speed with the spacer out?

Dave

09-18-2006, 09:49 AM

#113

articfriends

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Re: my bravo outdrive gear experiment

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Originally Posted by zt260

The 5 blade dropped my slip from 21-24% to 11 to 14% depending on rpm's. Even with the spacer out it still only ran 86.5 at 5700 w/5 blade. I have ran 90 this year with the box and no spacer with the 32 labbed and 87.5 to 89.5 with 30 pitch labbed. I love the strong midrange the 5 blade had but I can forsee new parts breaking in my drive on a regular basis after yesterday with one so I'm removing the box this winter and going back to old set-up-no box,std prop height,high 89's loaded down and 92-93 running light using 4 blade labbed props.I have a std 32 4 blade I will probably get labbed to a 31,maybe it will be a good prop to get me into the low 90's when running with a normal weight load in my boat. I wish the stellings box would have worked better but as we all know not every mod on these boats always works,Smitty

09-18-2006, 10:04 AM

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zt260

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Re: my bravo outdrive gear experiment

Is 5700rpm the max you normally run? Seems like you need to go up further with the drive.

09-18-2006, 12:39 PM

#115

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Re: my bravo outdrive gear experiment

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Originally Posted by zt260

Is 5700rpm the max you normally run? Seems like you need to go up further with the drive.

On the dyno motor peaked at 5700 ,90 % of the time I run my 30 labbed which will pull to 5800-6000 pretty fast depending on load. The boat felt sluggish with the 5 blade 28 pitch on it from 5000 up,after holding it at wfo it would build up to 5700 or so but you could just feel it straining the drive. My best speeds have been with a std length lower at 7 1/2 inches prop to hull c/l. The box moved drive up 1" which made boat porpoise,cavitate,run slower, etc,the spacer helped eliminate most of it but slowed me down even more. The boat didn't have any of the box "created" problems with a 5 blade on it with drive spacer out but still ran slower(86.5 at 5700 5 blade,w/box and prop up 1" vs 92.8 with no box,std prop depth,4 blade 32 labbed at 5700-5800. I could try a hydro p5x or a labbed 28 maximus 5 blade and leave box on the boat and maybe even run a shortie and still have have stellar cruise speed but I don't want to have a drive break every week on top of having the lower gears chewing up every 20-40 hours so I'm going back to my original setup,Smitty

09-18-2006, 01:16 PM

#116

cobra marty

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Re: my bravo outdrive gear experiment

Are you sure your motor is putting out the power? After your blown supercharger, Could you be down 1 pound of boost? That would equate to about 40HP and account for the 2-3 MPH loss of speed. The box is good and your slip numbers look great. If you take out the spacer it will lighten the load on your drive with the 5 blade.

09-18-2006, 02:59 PM

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Re: my bravo outdrive gear experiment

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Originally Posted by cobra marty

I'm not 100% sure motor is 100% but it will pull the rev limiter still with 30 pitch its just going 2-3 mph slower because of the box and set-up. I'm seeing 10-11 psi of boost at 5900 the same as the old supercharger.With the 30 labbed the boat goes from 60 to about 85 mph in about 5-7 seconds,with the 28 5 blade it takes about 15-20 seconds and you can feel everything just straining,thus the drive blowing after about 1 dozen test runs under boost. I'm going back to old set-up most likely (no box) because I ran 92.8 w/32 pitch before and am down 5-7 mph when running light when I actually look at before and after speeds. I'm sure a 28 labbed 5 blade might bring some of that back but I doubt its going to get me from the 86.5 it ran yesterday to 92 plus. When the drive broke yesterday with the 5 blade I wasn't running the spacer so I was 1" up. I'm sick of the negative results from the box so I'm going basck to square one. I will freshen motor this winter while I'm taking the box off just to ensure its 100%.These lower gears chewing up in 20-40 hours I can tolerate but shearing off shafts,getting stranded and destroying other parts gets exspensive real quick,Smitty

09-18-2006, 06:44 PM

#118

Elite Marine

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Re: my bravo outdrive gear experiment

I see a Konrad in your furture . . .

09-18-2006, 08:12 PM

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zt260

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Re: my bravo outdrive gear experiment

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Originally Posted by Pantera28-650HP

I see a Konrad in your furture . . .

Once you start closing in on 1000HP I see the Konrad blowing apart just as well. We have not found the perfect solution yet.

09-18-2006, 10:29 PM

#120

Big Block Billy

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Re: my bravo outdrive gear experiment

You tried very well , but you need a drive with bigger internals due to plastic deformation of metal and so forth.
You are asking a boy to do a man's job with the bravo...
KONRAD will be a great investment, and you would have spent less for it in both time and money, and experience less heartache......and more fun boating !!!
Maybe the Konrad uses a slight bit more power due to friction loss, but staying together is worth way more than 2 MPH and blown up drives that are now worthless...
Not to be a pain in the a$$ but my friend and I were the first on Long Island to run the Konrads and believe they are the best drive for the money, etc... And that was 2 seasons ago.. BBB

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