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  1. #1
    Join Date
    Apr 2002
    Location
    Florence, AL
    Posts
    778

    Default WOT RPM on '92 PCM 5.8 Pro Boss

    I have a '92 Mariah with a PCM 5.8 Pro Boss and 1.23:1 reduction gearbox. RPM at WOT is about 4000 with 3 people and a fulltank of gas. The highest i've ever seen is 4200 with a very light load. Should the rpm be higher than that. The boat has the original OJ 14x16 3-blade nibral prop on it. I had it straightened and balanced at the beginning of the season. There is VERY little vibration. Am I overpropped, is this just the nature of this older beast, or do I have some other mechanical problem? Thanks in advance for any insights.

    DKJ
    1992 Supra Mariah - Red
    PCM 351HO 285hp - PCM 1.23:1 Transmission
    OJ XMP 4 Blade CNC 13x15.5RH

    "People do weird things to boats" -Unknown

  2. #2
    Join Date
    May 2002
    Location
    Charlotte, NC
    Posts
    88

    Default

    I reach about 4400 rpm on my '90 Sunsport with a PCM 351 and the 1.23:1 reduction transmission. It too has the 14x16 3-blade nibral prop. Its top end is close to 42-mph. If yours starts, runs and pulls well, enjoy it.
    2005 Supra 21V
    1990 Supra Sunsport Classic SOLD
    ------------------------------

  3. #3
    Join Date
    May 2002
    Location
    Syracuse, NY
    Posts
    19

    Default

    Prior to making any changes or alterations I would STRONGLY recommend verifying the accuracy of the tach in the boat.

  4. #4
    Join Date
    Aug 2002
    Location
    lake of the ozarks
    Posts
    8

    Default

    I have an 89 sunsport with a pcm 351 1.23:1 transmission and a 14X14 prop. I turn 4200rpm at wot. My dad has a 91 sunsport with the same set up and he turns 4600rmp at wot.
    the boats run the same speed on gps, so I think that there might be some issues with the tach on sunsports. hope this info helps.
    supra lover

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