Considering Bravo to Volvo Duo-prop

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10-15-2011 | 08:00 PM

#11

36Tango

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From: Cedar Rapids Iowa, LOTO, Cape Coral Fl.

Quote:

Originally Posted by Mbam

Yes, but I am sure the volvo has the same inherent limits. The 450HP should not be a problem with a small block.

The only problem you will have is finding the ratio you need. You will most likely run out of prop (30 is max that is made) with the standard gas ratios of 1.81 to 2.2. They are available all the way down to 1.36, but you will not have to go that far.

What ratio is your Bravo 1? How many RPM do you want to turn?

You can play around here:

http://go-fast.com/Prop_Slip_Calculator.htm

My Bravo 1 is a 1.5 gear ratio. I'd like for WOT to be about 5000. I have no idea how to figure out props for a B3. Any suggestions would be great!

What is meant by "oil provision"? Will any B3 lower bolt up to any B1 upper?

Last edited by 36Tango; 10-15-2011 at 08:03 PM.

10-16-2011 | 07:59 AM

#12

Mbam

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From: Pompano Beach FL, USA

How fast does the boat go now? How much power currently? What prop and RPM now? How old is your current drive? The early bravo's do not have an oil circulation passage connecting the upper & lower, this was added in 1991 or so.

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10-16-2011 | 10:02 AM

#13

A.O. Razor

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Not to be a stick in the wheel here. But 80 mph with 450 hp... through a duo prop setup??? Anyway. With a 1.5 gear and 5000+ rpm, 28" would be needed to run 80.

Good luck with it.

Last edited by A.O. Razor; 10-16-2011 at 10:04 AM.

10-16-2011 | 10:10 AM

#14

Mbam

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From: Pompano Beach FL, USA

I did some work on a 28' bat boat when Reindel was leasing them. Had Volvo duo-prop and a stock 502. Went really close to 80. 78 seems to stick in my mind. Bat Girl would probably remember. I think it's do-able.

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10-17-2011 | 03:15 PM

#15

C_Spray

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From: Coastal North Carolina

Jeff, If you want to go the DPX route, I have a transom assembly, two bellhousings and several 1.47 drives, all used, but in good shape. I also have a couple of sets of E4 props, which translates to roughly 90 mph at 5200 rpm.

The Batboats are so narrow that they really respond to the lack of prop torque from the DPX. Reindl would have engine/drive height data for your V24.

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10-17-2011 | 05:28 PM

#16

36Tango

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From: Cedar Rapids Iowa, LOTO, Cape Coral Fl.

Quote:

Originally Posted by C_Spray

As much as I would love to have that drive on my boat, it is just too spendy for me to do right now. I just talked to Chris a few minutes ago and we are going to try to dial in a Bravo3. Now, if I had a buyer for my engine coupler, transom assembly, 1.5 Bravo one with a 28, 30, and 32 stainless props I would be in business. Oh yea, I guess that I would no longer need my Marine Machine external hydraulic steering either.

Hopefully we can find the right deal on a B3 and see how well we can get it to work.

Thanks!