3.0 to 4.3

Discussion in 'Gas Engines' started by sethvw, Apr 5, 2007.

  1. sethvw
    Joined: Apr 2007
    Posts: 5
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    Location: indiana

    sethvw Junior Member

    Hello all,
    I am new to boatdesign, but really like the site so far. I have a 21 ft v-hull with a Merc. 3.0 l 4 cylinder. The boat runs good, but I would like some oppinions on swapping in a 4.3 v6. I know the gas usage would go up but could use a little extra power. I have changed props, but believe the boat is a little large for the 3.0. What issues will i have with connecting outdrive?
    thanks seth
     
  2. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Both these engines generally ship with the Alpha outdrive. You may need to change the gear ratio in the drive (the 3.0 uses a gear ratio of either 2.0 or 2.4, while the 4.3 uses 1.62, 1.81 or 2.0 depending on boat weight and type), and you will almost certainly need to change the prop. Depending how the engine bay was originally built, the engine mounts might need some work.
    I don't believe this swap is considered a complicated one; as far as I know it's a pretty common procedure.
     
  3. sethvw
    Joined: Apr 2007
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    Location: indiana

    sethvw Junior Member

    v6 conversion

    thanks for reply. how can I find the gear ratio? It is a rather large boat for the engine. I have found that the same (and even smaller boats) was available with 4.3. I have taken some measurement and the engine compartment looks good. How can I find information on exhaust conversion, bolting to out drive, etc?

    thanks again
    seth
     

  4. Zackman
    Joined: Dec 2006
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    Location: Louisiana

    Zackman Junior Member

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