big jet ski hp?

Discussion in 'Jet Drives' started by quadstage, Nov 20, 2015.

  1. quadstage
    Joined: Nov 2015
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    quadstage New Member

    Does anyone know the limit to how much hp a PWC pump could reasonably handle?

    would changing/beefing up a drive shaft to the impellor allow for larger motors?

    I saw somewhere someone using bigger hp on a typical Pwc pump.
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I'm sure you could increase the power by a small percentage, but too much power will make the pump cavitate and lose thrust. A bigger shaft will decrease the volume the pump can handle and decrease the trust too.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Typically the pump is sized to the motor, so if you want a little more, you can spin it up a bit and apply more torque, but if you want a lot more HP, you'll need both a bigger pump and more powerful engine. Think of it as a water pump, sucking water from a well. If you have a well that uses a 2 HP pump and this gives you a specific volume and you want more, both the pump and the motor will need to be bigger, to handle the increased volume.
     
  4. quadstage
    Joined: Nov 2015
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    quadstage New Member

    Thanks Gonzo and Par.

    It might work then.

    I was just thinking of doing a Glen-l Dyno Jet, but adding a Subaru boxer maybe 150 or so hp (I think thats what the hp rating is on those?). I am a large adult so a 650 cc and up engine is about the lower limit.

    I also thought of modifying a 14 ft'er with a jet pump. A design called the "Celerity" 16 degree deadrise at the transom seems about right for what I am doing.

    I don't like wood for river travel but might be able to substitute Aluminum for wood.

    The costs of a new pump are incredible as I have just found out.

    I might be able to get a used 7.5 inch pump on Meanchicken but it would be easier to get a good axial pump from a used PWC?
     
  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The 650 motor is rated at 50HP. 150HP is way too much. If you are buying a pump from a jetski, might as well buy a whole running setup.
     

  6. quadstage
    Joined: Nov 2015
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    Location: Canada

    quadstage New Member

    good advice. wasn't sure on the Hp of a 650. if possible I'd like a 1000 cc like on the NZ jet dingies. a 4 stroke would be good i think they are using stock Pwc pumps?.

    I am also guessing they are heavy compared to the same size wood boat. any ideas on beefing up the hull and still keeping the weight down for rock crunching just in case? Cope boats has a nice little 11 ft design but the Dyno jet is superior handling and design to my knowledge.
    I thought 150 hp would be great?
    check this out
    13 ft Ls1 engine!

    https://www.youtube.com/watch?v=yWpW_RZi3HI
     
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