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  1. #1
    MDGPR's Avatar
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    high rpm, low speed, hull?

    I have a 05 gpr with everything listed in my signature. Last season before jims FF plate i was turning dynafly 7320 rpms and hit 69 mph. I could take anything in low end except a few heavily moded rxp's.I checked my pump shoe and everything and it was not hanging down. With my rpms i am almsot positive it isnt an engine problem and it somethign with the hull or pump. I think my problem was in my stock unmoded R&D plate. It was my first mod in 05 and i bolted it right up and bent the flat venter surface. You could see a lump coming out coming out of the plate on the center flat part. This winter i sent my stock R&D plate to jim and he fixed the bump and made it a FF plate.

    My question is how many MPH could this rob from me? i was thinking i should have about a 73 mph boat with my mods and an unmoded plate. I am hoping to come back close to 75 from what iv read of the advantages from the FF plate.

    My secound question is i ran 7320 rpms in 90 degree weather, Should i pitch up or keep my 14/20?

    thanks in advanced.


  2. #2
    Duke's Avatar
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    MD the rpms are way outa wack. I run close to 76 with an untouched DF at 7280. What tach are you using? Not doughting you ,just want to help figure out whats going on with your setup.

  3. #3
    MDGPR's Avatar
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    TT commercial, that could be part of my problem but it has seemed to be reasonably close, before my reeds it was reading around 7250

  4. #4
    Duke's Avatar
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    Not part of the problem just brings dought on the rpm readings. Your mods should have you around 74. Have you checked the pump shoe height?

  5. #5
    MDGPR's Avatar
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    yes, carl at island actually fixed it it was all screwed up. i wasnt sure about the jetworks so i had him do it and he fixed that too.

  6. #6
    DAGO RACING CREW 97GPSLEEPER's Avatar
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    If the impeller housing is out of spec., the RPM's can be high with no gain in speed.

  7. #7
    Duke's Avatar
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    Quote Originally Posted by 97GPSLEEPER View Post
    If the impeller housing is out of spec., the RPM's can be high with no gain in speed.
    This is very true but he indicated the holeshot was excellent beating RXPs etc. so I figured it was good.

    MD does it cavitate out of the hole or have good hookup?

  8. #8
    MDGPR's Avatar
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    no it doesnt caviatte and hooks up fine. I think alot of the reason is because of the hump i had in my stock RD plate . I havent gotten another reading with the FF plate yet. Too cold and some ice is still in the river.

  9. #9
    r33pwrd's Avatar
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    Same mods as me in running 73 at 7200 rpms... Check that prop!

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