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  1. #1
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    21 super boat with 225 3l rigging!!!

    Sup guys. Just rerigged my 21 superboat with a 2005 225 optimax. Im very underwhelmed with the performance on it compared to the old 200 2.4l. It has a 23 pitch tempest prop and a stock setup all around. Its only getting about 5k rpm wot and only hitting low 50's. I love how well the engine runs but I need more performance. Would love some input on where to start to improve performance. First off, prop? Lower unit?

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    You didnt say anything about set back so here goes. About 8" of setback for general running around. Motor should be no deeper than 2" below pad, higher if you can maintain 10lbs of water pressure at WOT. 4 blade prop that will give you more bow lift. Trophys in the 24-25 range will work well as do 3 blade 26 chopper. Gotta get that motor into its powerband or your gonna hurt it. We just rigged a 22 Velocity, new style with a 225 opti and 24 trophy and it sees mid to high 60's with a boat load of fuel and kids. JMO

    Other will chime in

  3. #3
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    Make sure your getting full throttle. That adjustment gets tons of people. Make sure its firing on all cylinders. They sound great on five too. Try the things that are free first.

  4. #4
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    If I recall you have actually a 21' Super/Challenger copy? You also have a 6" setback ? Your boat most likely is much heavier than an early model Superboat and without knowing how much more I would just suggest trying 16" setback at least and see how that helps. I'm just getting a feeling you need way more lift.
    Last edited by dnelson964; 07-03-2014 at 10:05 AM.
    1990 22' Activator Yami HPDI 300-sold
    1976 21' Challenger 2002 3.1 Yami 250 Vmax phase lll 89.7-sold
    1982 21' Superboat
    1990 22' Activator yami OX66 Vmax 250
    1982 30' Scarab-twin 200 Merc-sold
    1979 21' Challenger 300 Evenrude-sold
    1979 21' Superboat 200 Merc-sold

  5. #5
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    I spoke woth a mechanic friend and he told me to check to see if im firing on all cylinders. Just hoping I dont have a bad cylinder. So thats step one

  6. #6
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    Quote Originally Posted by vnemous View Post
    You didnt say anything about set back so here goes. About 8" of setback for general running around. Motor should be no deeper than 2" below pad, higher if you can maintain 10lbs of water pressure at WOT. 4 blade prop that will give you more bow lift. Trophys in the 24-25 range will work well as do 3 blade 26 chopper. Gotta get that motor into its powerband or your gonna hurt it. We just rigged a 22 Velocity, new style with a 225 opti and 24 trophy and it sees mid to high 60's with a boat load of fuel and kids. JMO

    Other will chime in
    Right now I only have a 6 inch set back. And when u say 2 inches below the pad. Where am I measuring from on the lower?

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    Quote Originally Posted by 88starflite21 View Post
    Right now I only have a 6 inch set back. And when u say 2 inches below the pad. Where am I measuring from on the lower?
    The propshaft.

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    adjusted the throttle and that was the issue. NOw when i trim up im getting about 5800-6000 rpms. So I guess its time to prop up. Also I'm cavitating out of the hole and have to feather the throttle. And the engines as low as I can set it on the jackplate I have.

  9. #9
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    Does that prop gave PVS holes? Are they wide open or are there plugs in them? If they're open or have plugs with large holes you may have to try solid ones or ones with no holes.
    I was going so slow I almost crashed. - JamesGang

    1978 24 Superboat - 250 EFI
    Sold: 1991 Starliner - 250 EFI Merc 3.0

  10. #10
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    Quote Originally Posted by JohnR View Post
    Does that prop gave PVS holes? Are they wide open or are there plugs in them? If they're open or have plugs with large holes you may have to try solid ones or ones with no holes.
    Yes they have holes in them. Im looking for a larger pitch prop anyway

  11. #11
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    You can get a set of the plastic PVS plugs for yours pretty cheap for now and if you end up with another Merc prop you may need them anyway. I've got a few 24's in the For Sale section, the 4 blades one one make a pretty good all around prop and then get a 26 Chopper for top end running.
    I was going so slow I almost crashed. - JamesGang

    1978 24 Superboat - 250 EFI
    Sold: 1991 Starliner - 250 EFI Merc 3.0

  12. #12
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    The cavitation is also called ventilation and often needed to spin a prop to get on plane. Depends on the application. A chopper definitely will.

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