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Prostar (Powerslot) Engine RPM at 36mph

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  • Prostar (Powerslot) Engine RPM at 36mph

    Hey everyone. I am working to reprop my 1993 Prostar 205. The boat has a Carbureted 351W with a Powerslot. As some of yall know, I recently rebuilt the motor and put a slight cam and also a edelbrock intake mainfold.

    I was wondering if yall can give me some feedback on what kind of props yall are running for this kind of setup. I am looking for WOT numbers and speeds as well as what RPM's yall are turning (based on perfect pass Tach) at 36mph?

    I am currently seeing 4000rpm at 36mph. That seems pretty high to me. Thanks a lot

    Sam

  • #2
    What is the size of the current prop? Has this prop been repaired?
    Eric Johnson
    Johnson Propeller Co., Inc
    OJ PROPS 800-359-9730

    Comment


    • #3
      That's pretty high for 36 mph.
      Previous: 1993 Prostar 205

      Red 1998 Closed Bow Ski Boat, Ford 351, 310 hp, Acme 4 blade, Perfect Pass SG.

      FAQ


      Tyler Ski Club


      To me, this forum is about love of inboard boats. It is about the sharing of information and, on a good day, some humor. It is not about post count, brand of boat, or any other superfluous labels that lend themselves to a false sense of superiority. Please, respect one another, try to pass on accurate information, and keep your eye on the ball.

      Comment


      • #4
        I enjoyed the 14x18 OJ 4 blade prop on that setup ... around 43 MPH top speed...... 4400 RPM was the WOT is recall properly
        Keep a tight line, and a smile on your face. Peace out.
        2008 Prostar 214 MCX
        Previous 93 Prostar 190 1.5:1 GT40

        "Left Foot Forward and preferring girls."

        Comment


        • #5
          I imagine a reprop will get the revs of that boat right in the sweet spot at ski speeds and really clean up the wake. My guess is that it ought to be running about 3525 rpm, maybe 3526, whatever it takes.
          Previous: 1993 Prostar 205

          Red 1998 Closed Bow Ski Boat, Ford 351, 310 hp, Acme 4 blade, Perfect Pass SG.

          FAQ


          Tyler Ski Club


          To me, this forum is about love of inboard boats. It is about the sharing of information and, on a good day, some humor. It is not about post count, brand of boat, or any other superfluous labels that lend themselves to a false sense of superiority. Please, respect one another, try to pass on accurate information, and keep your eye on the ball.

          Comment


          • #6
            With a std 14x18 prop powerslot setup engine rpm should be actual MPH, give or take a few. Ie 3600 RPM =36mph. Sounds like you need to add some more cup to your prop. Over time as props are overhauled they lose diameter, so you might need to add 1/2" pitcht or so. A good shop should be able to determine what they need to do based on current performance and what you want.
            1988 PS190 Powerslot, INDMAR 351W, Edelbrock Intake, MSD Ignition,

            Comment


            • #7
              The RPM at 36 MPH should be 3600. Would take a fair amount of cup to the current prop to drop it down that far. An add of a 1/2" of pitch would be a crap shoot at best.
              Eric Johnson
              Johnson Propeller Co., Inc
              OJ PROPS 800-359-9730

              Comment


              • #8
                Thanks for the replies so far. As far as the prop, It is a un repaired un damaged 4 blade 13.50 x 16.00 (.105 cup).

                At wide WOT I am cruising 42.5 (on GPS), at 4830rpm.

                The boat is used mainy for course skiing, but I will weight the boat and throw 4 or 5 people in it and wakeboard on the weekends. 750lbs in the back and 300 in the ski locker + people.

                So I would like the prop to be able to do both well, but I understand that there will have to be some compromises.

                So for the guys with the slot it looks like yall are seeing close to 1:1 RPM to speed? (ie 36mph = 3600 rpm give or take)?

                Comment


                • #9
                  The prop you are running needs to be replaced. A standard 14 X 18 LC 1 1/8" 4-blade should lower the RPM at 36 as well as WOT.
                  Eric Johnson
                  Johnson Propeller Co., Inc
                  OJ PROPS 800-359-9730

                  Comment


                  • #10
                    Originally posted by samtechwaterski View Post
                    Thanks for the replies so far. As far as the prop, It is a un repaired un damaged 4 blade 13.50 x 16.00 (.105 cup).

                    At wide WOT I am cruising 42.5 (on GPS), at 4830rpm.

                    The boat is used mainy for course skiing, but I will weight the boat and throw 4 or 5 people in it and wakeboard on the weekends. 750lbs in the back and 300 in the ski locker + people.

                    So I would like the prop to be able to do both well, but I understand that there will have to be some compromises.

                    So for the guys with the slot it looks like yall are seeing close to 1:1 RPM to speed? (ie 36mph = 3600 rpm give or take)?
                    I've had two boats. One was a MC with 1:1. It ran 36 mph at 3,475 rpm. My current boat is a SN with 1.23:1. It runs fewer than 3,600 rpm at 36 mph as well. Give or take is the key. FWIW, I'm about 450' ASL. If anything, just remember that there are no hard an fast rules when trying to figure how a boat will act on the water. Getting repeatable results is as much due to luck as anything.
                    Previous: 1993 Prostar 205

                    Red 1998 Closed Bow Ski Boat, Ford 351, 310 hp, Acme 4 blade, Perfect Pass SG.

                    FAQ


                    Tyler Ski Club


                    To me, this forum is about love of inboard boats. It is about the sharing of information and, on a good day, some humor. It is not about post count, brand of boat, or any other superfluous labels that lend themselves to a false sense of superiority. Please, respect one another, try to pass on accurate information, and keep your eye on the ball.

                    Comment


                    • #11
                      Wot

                      Originally posted by EJ OJPROP View Post
                      The prop you are running needs to be replaced. A standard 14 X 18 LC 1 1/8" 4-blade should lower the RPM at 36 as well as WOT.
                      Should be 1:1 (3600rpm to 36 mph)and just because you saw 4800rpms with that prop don't mean your gunna see 48mph. But you will save some wear and some gas.

                      I had a 1990 ps 190 351 power slot. Sometimes footin in the fall on Telico both spedo's would pick up trash and you have to use the tach to tell what your speed is.

                      Peace W

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