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  1. #1

    Question Replacing Volvo 4.3GS (Volvo 290Duoprop) with Mercuriser 6.2- 350HP

    Hello everyone,
    I have Sealine S28 Bolero 1996 boat with two Volvo 4.3GS engines, Volvo 290 Duoprop sterndrives.I would like to replace the engines with Mercuriser 6.2L-350HP engines on my remaining sterndrives.What changes,modifications should I do? Is it possible or not?

    Thanks everyone in advance )

  2. #2
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    17,292

    Default Re: Replacing Volvo 4.3GS (Volvo 290Duoprop) with Mercuriser 6.2- 350HP

    More gearing in the outdrive.

    Jeff

  3. #3
    Join Date
    Dec 2006
    Location
    Greenfield Me. USA
    Posts
    6,286

    Default Re: Replacing Volvo 4.3GS (Volvo 290Duoprop) with Mercuriser 6.2- 350HP

    Ayuh,..... Not only will there be oodles of problems puttin' Mercs into Volvo engine beds, yer drives will need to be regeared as Jeff mentions,....

    Fuel, electrical, exhaust, Everything will have to be re-engineered,....
    Any Grease is Better,... Than No grease at All....

  4. #4
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,759

    Default Re: Replacing Volvo 4.3GS (Volvo 290Duoprop) with Mercuriser 6.2- 350HP

    Merc to Volvo beds not issue... V6 to V8 spacing from transom to engine support lag screws on stringers is the issue. Also as previously posted reduction for 8 and 6 cylinder engines different. Given hideous prices for parts from Volvo, you may be better off just changing the lower 1/3 of the drive legs... all "reduction" gearing takes place there. Gearing in top 1/3 is just fwd/n/rev. Lower 1/3 often avail used.... AND.... I discovered that the exhaust porting thru the transom and lower unit on 200 series Volvo drives is too small for V8s. Merc specifies (for 5.7 for example) that the exhaust port, if a single needs to be 4" dia, 3" if duals. The equivalent diameter on later 200s is less than 2 1/2". I changed my thru drive exhaust to thru transom (with dual 3"centek shorty mufflers) I got another 450 RPM at WOT. Even if you stay with thru drive, exhaust routing will be a challenge.
    Last edited by sandkicker; 01-19-2022 at 10:32 AM.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  5. #5
    Join Date
    Sep 2010
    Location
    Jersey Shore
    Posts
    6,453

    Default Re: Replacing Volvo 4.3GS (Volvo 290Duoprop) with Mercuriser 6.2- 350HP

    You have a 1996 boat with Volvo Penta AQ290 drives?
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  6. #6
    Join Date
    May 2010
    Location
    DC Burbs/Maryland Eastern Shore
    Posts
    2,379

    Default Re: Replacing Volvo 4.3GS (Volvo 290Duoprop) with Mercuriser 6.2- 350HP

    Pardon my language, and don't take it personally, but there's not much to be gained by repowering a great fat whale of an express with bigger engines. You MIGHT get a couple knots of high end out of it. You'd still be pushing the same hull, same weight (ugh), with the same old drives and propellers. If you have visions of skittering across the wave tops like a Pete Fountain racer, well, um, no.
    These bloated luxo-pads are designed for entertaining, weekending, and generally behaving like a water borne RV. Am I being harsh? Probably.
    If it were me, and I was looking at the 40,000 quid for just the parts (no idea on installation costs over there) I would start looking around for a faster boat that was more in keeping with my needs.
    Practicing the ancient art of ren-ching

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