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  1. 06-23-2009, 08:04 PM #1
    nicksterious
    nicksterious is offline Junior Member
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    Default RPM to MPH Conversion (broken speedo)

    I have '08 24' Supra Sunsport. The paddlewheel that registers mph isn't working correctly and new ones are backordered.

    I can set perfectpass with RPM's but I can't figure out what the conversion ratio is.

    Is there a chart or formula to help figure this out? I don't have a GPS unit to use.

    Basically, I need 10mph, 16mph and 19-20mph in RPM's.

    Any help would be greatly appreciated.
    Last edited by nicksterious; 06-24-2009 at 11:50 AM.
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  2. 06-24-2009, 06:53 PM #2
    RED WINE ROCKER's Avatar
    RED WINE ROCKER
    RED WINE ROCKER is offline Member
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    Your gonna need a guy with the exact same boat to answer that.......i have a 21-launch....i use "rpm" for skiing.....at 3200 gives me about 31 mph/ plate down.
    RED WINE ROCKER~2005 SUPRA LAUNCH 21 (PHOTO BOAT!)
    LAKE LANIER/LAKE BURTON/LAKE BLUE RIDGE


    http://www.myspace.com/atlantawhiskeydawgs
    ...my band this year.
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  3. 06-25-2009, 07:19 AM #3
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    mapleleaf
    mapleleaf is offline Senior Member
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    The Rocker's right, prop size and everything come into play here...
    Maybe get somebody ina boat beside you, with a working speedo??????Gauge speed and rpm off their speed...
    90 Conbrio
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  4. 06-25-2009, 12:41 PM #4
    87SunSportMikeyD's Avatar
    87SunSportMikeyD
    87SunSportMikeyD is offline Senior Member
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    car gps should tell you the speed
    --WakeMikeys 1987 Supra SunSport--
    Thread - https://forum.supraboats.com/showthread.php?t=3630
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  5. 07-09-2009, 08:17 PM #5
    saltare inverts's Avatar
    saltare inverts
    saltare inverts is offline Senior Member
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    gps works great
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