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Thread: Thrust to Hp

  1. #1
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    Thrust to Hp

    Hp = (F x v)/550

    F = thrust... lbs
    v = velocity.. f/s

    F(orce) = pump inlet area(inch^2) x pump inlet pressure(lbs/inch^2)

    v, you can get using a GPS @ WOT(make sure you convert mph to feet/second)

    With a pressure gage attached to the inlet water line from the pump and a GPS you can calculate the Hp at the venturi, if you want a project and something to do.

    Everything needs to be in inch, pound units.


    Regards

    Rick

    Not to easy or convenient to dyno a PWC, here is a way around it.


  2. #2
    This, of course, is an incorrect application of engineering and physics. And, as such, the results will be wrong.

    Example: secure your PWC to the trailer, fire up the engine and rev to half throttle. A pressure gauge will show substantial pressure at the nozzle while the GPS will read zero. The incorrect math supplied would yield a delivered impeller HP rating of 0... which is completely incorrect.

    That is just an example of how this math and logic is incorrect. The results will actually be wrong in almost all cases.

  3. #3
    Moderator RX951's Avatar
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    Quote Originally Posted by The_Giz View Post
    This, of course, is an incorrect application of engineering and physics. And, as such, the results will be wrong.

    Example: secure your PWC to the trailer, fire up the engine and rev to half throttle. A pressure gauge will show substantial pressure at the nozzle while the GPS will read zero. The incorrect math supplied would yield a delivered impeller HP rating of 0... which is completely incorrect.

    That is just an example of how this math and logic is incorrect. The results will actually be wrong in almost all cases.
    welcome to the forum Giz

  4. #4

  5. #5
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    Quote Originally Posted by The_Giz View Post
    SALUTE!

    It's already been done

    I can prove it using my own ski, but I'm not going down that road with you anymore.

    As usually the same BS. Isn't there enough over at PWCTODAY

    I could supply you with all the proof you would ever need, like I said I'm done with you.

    regards

  6. #6
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    Quote Originally Posted by The_Giz View Post
    This, of course, is an incorrect application of engineering and physics. And, as such, the results will be wrong.

    Example: secure your PWC to the trailer, fire up the engine and rev to half throttle. A pressure gauge will show substantial pressure at the nozzle while the GPS will read zero. The incorrect math supplied would yield a delivered impeller HP rating of 0... which is completely incorrect.

    That is just an example of how this math and logic is incorrect. The results will actually be wrong in almost all cases.
    Actually 0 Hp is a 100% correct because the ski is not moving, just proves your lack of knowledge on ME.

    The ski has to be moving in order for work to be done and Power = work x time

    Like I've told you many times, you are not a M.E. quit trying to play one.

  7. #7
    Moderator RX951's Avatar
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    ??? uhm. whats with all the snippiness? uhm, we have a new member on the forum, and he just posted his opinion?

    please advise

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    Quote Originally Posted by RX951 View Post
    ??? uhm. whats with all the snippiness? uhm, we have a new member on the forum, and he just posted his opinion?

    please advise
    I'm not trying to be snippy.

    I've known Giz for 10 years on the boards.

    He's wrong, if that's construed as snippieness on my part, sorry.

  9. #9
    Quote Originally Posted by ski pimp View Post
    Actually 0 Hp is a 100% correct because the ski is not moving, just proves your lack of knowledge on ME.

    The ski has to be moving in order for work to be done and Power = work x time

    Like I've told you many times, you are not a M.E. quit trying to play one.
    That would be incorrect. Substantial horsepower is being generated by the engine and it is present at the impeller and nozzle. That is pretty obvious to just about everybody. To imply or state otherwise is well.... silly at best.

    All kinds of work is being done. It's just not resulting in the movement of the PWC.

    Your logic is flawed/incorrect.

  10. #10
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    Quote Originally Posted by The_Giz View Post
    That would be incorrect. Substantial horsepower is being generated by the engine and it is present at the impeller and nozzle. That is pretty obvious to just about everybody. To imply or state otherwise is well.... silly at best.

    All kinds of work is being done. It's just not resulting in the movement of the PWC.

    Your logic is flawed/incorrect.
    You're going to have thrust or F at the nozzel, but 0 ski velocity sitting on a trailer which will yeild 0 Hp at the nozzel.

    Thrust and Hp are not the same thing.

    You are truely lost, and I'm not going down this road again.

    regards

    Were talking about Hp at the venturi, not at the engine.

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