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I am rebuilding a 454 550HP engine in my 1991 Sundowner. Which twin prop outdrive is better: the Volvo or the Bravo 3? The boat will be used mainly in saltwater and occasionally in freshwater.

All input would be appreciated as this is my 1st boat.

I have had A B3 drive for the past 10 years. A good drive with no problems, other than (found out the hard way when I was baiting a lobster trap) don't shut the engine down when in gear.

The other point here is that you are keeping it in salt water. The Mec is a aluminum drive, I have tried at least 4 brands of paint and the growth come back within 2 months, some times it lasted a little longer. This is my first Volvo drive and the end of my first year with it. It is a XDP drive which is a composite drive. I painted the drive, BUT it lasted at least 4 months and at the end of the season 5 & half months, had very little growth on it.

Now the boat did stay on the slip the whole time. Almost every weekend it was used. I think there was only 3 weekends all summer we did not go out. I will stay with Volvo, at lest for now!!

Keep in mind, that the raw water system, could be a lot different between the 2 drives. I don't know how easy or hard this is going to be. I only know the XDP on the Volvo side. It might be smarter and/or cheaper to stay with the stock drive. You are not stating if the engine is a Mec or Volvo. Even if its a Mer with a Alpha drive the raw water system is very different than a B3 drive!! The more I think of it, it could not be a Alpha because of the size engine you have. It must be a B1 drive if a Merc, than the change over would be a lot easyer!

I'm not sure if either duo prop drive is made for 550 HP. The DP drive is much more hydrodynamic than the Mercruiser BIII. Stock 454 is 330 HP in 1991.

From Mercruiser BIII literature from our boat.

Then there is this from Mercruiser spec table:



I suppose it can be done, but not worth it in my book for that hull and age of boat.

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

What drive system did it come with originally?
Merc or OMC?
I would not use a Volvo composite or OSI drive, they have been problematic with respect to leaking bellows and Volvo actually discontinued the drive, they have a new salt water drive called the Ocean X...no idea if its been proven yet or not.
On a boat that size I can see you wanting a DP, I'd go with whatever is easier to get parts for locally.
If the boat is trailered the salt water use is not a big deal, but if it's moored or slipped in salt you will be in for a lot of maintenance.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II