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  1. #1

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    Impeller options

    Maybe a bit of a newbie question,

    But why is it that a honda rus such a high pitch impeller compared to other makes of ski? that still get simillar speed readings.
    Seadoo 185 has a 13/23, 215hp has a 10/21 option, 255hp 14/25 option, 16/21 for a kawasaki 300x.

    So my point is, does the speed/cavitation issues lay soley in the pump and not the hull?

    Has anyone ever tried lowering the pitch this far on a r-12x?
    Or re powered a ski hull with proven speed readings with a honda?
    Or played with the pumps nozzel, removed vanes, knife edged them?

    Iv just completed a jet boat build with a r-12x and see basicly the same performance from what i had when engine etc was in the ski hull.

    Any input would be great.


  2. #2
    supermac's Avatar
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    the honda makes power at a lower RPM, hence the steep pitch.

    A steep pitch promotes cavitation.

    The answer is less pitch, but you need a larger diameter pump to consume the power without over revving the engine.

    On your boat, I would try to retrofit a modern sea-doo pump. They are pretty good and relatively inexpensive. The driveshaft/spline becomes your next challenge to adapt to the honda.

  3. #3

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    Doesnt the honda run a 155 pump as with most seadoos? And wouldnt i just run into the same problem as you said with the power being delivered at a lower rpm? Realy id need to lift the rpm and lower the pitch on the impeller?
    Last edited by LiquidAsset; 09-19-2013 at 09:34 PM.

  4. #4
    supermac's Avatar
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    The sea doo has far less pitch. They make similar power at 1000 rpm higher with less torque. Cavitation is a product of the low pressure in front of the impeller, which is a direct result of the pitch.

    Don't try and retune the engine. You need to tune the impeller and pump to the application.

    A larger diameter pump will be a better fit for your application.

  5. #5
    supermac's Avatar
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    The sea doo has far less pitch. They make similar power at 1000 rpm higher with less torque. Cavitation is a product of the low pressure in front of the impeller, which is a direct result of the pitch.

    Don't try and retune the engine. You need to tune the impeller and pump to the application.

    A larger diameter pump will be a better fit for your application. Sea doo uses a 158mm pump in their 260 crafts.

  6. #6

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    Oh sweet, i will be on the look out for a pump then, cheers for the input

  7. #7

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    If I were to add in a rpm/throttle position boost controller to give me a lower boost at hole shot would this help my cavitation? and would the Honda ecm accept it?

  8. #8
    supermac's Avatar
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    the stock ecu already does that. I wouldn't cripple it any more. Fix the problem not the symptom!

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