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  1. #1

    What is the real function of the blower clutch on one of these bikes?

    What is the real function of the blower clutch on one of these bikes?

    1) Limit the max boost out of the supercharger to the Seadoo spec? So it constantly slips at some boost level? Wow that would be hard on things....

    2) Limit the max acceleration of the RPM of the blower as the bike comes in and out of the water and rev limiter? Somewhat less hard on things. Smooth water bikes should have less where than the guys doing lots of jumping.

    3) Save the motor, blower gears... if something ugly tries to get thru the blower? Why would it ever need rebuilding unless something ugly happened.

    4) Something else...

    Andy


  2. #2
    Vern's Avatar
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    4) Something else ... It is a slip clutch, designed to allow the SC to freewheel occasionally (under right conditions) so it does not break gears, teeth or the clutch shaft. People have eliminated the clutch slip a few different ways, always with the same result ... eventually the SC shaft breaks.

    It is the only centrifugal SC that has a clutch that I have ever seen; have never seen this application on another engine/SC setup. I think it is mostly due to the violent acceleration/decceleration that occurs when hooking/unhooking while holding full throttle ... very hard on the rotating masses. The clutch mostly comes into play with rough water/WOT ... you will hear it 'chirping' when it slips usually.

  3. #3
    GasResearch-VT.SE's Avatar
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    I wonder how a 3mm walled steel shaft would feel changing from 8900rpm to 6000rpm in 0.1 of second...

    Over 100nm with a 300gram assembly?
    Just guessing here the amount of G's... Maybe over 100g's?

    Its job is to soften the transition from sharp rpm changes on the direct driven shaft.

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  5. #4
    I was betting choice number 2.

    Andy

  6. #5
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by GasResearch-VT.SE View Post

    Its job is to soften the transition from sharp rpm changes on the direct driven shaft.
    Exactly!

    There have been those that thought they didn't need the clutch because they were using a blow off valve so they locked the clutch up.
    Needless to say they ended up retrieving metal debris out of the bottom of their motors

  7. #6
    Blow off valves are actually a device to assure that airflow always continues to go the same direction thru the turbine. Strange things happen when the air tries to go backwards and small parts in the motor tends to be the result.

    Andy

  8. #7
    GasResearch-VT.SE's Avatar
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    Blow off valves do more damage than good on the SC seadoo's.

  9. #8
    How is that? What is the downside? I would think it would drive the EFI mapping nuts if any of the base fueling is Alpha-N.

    Andy

  10. #9
    GasResearch-VT.SE's Avatar
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    BOV increases clutch wear and heat on the clutch.

    Its fine, the TB does a good job.

  11. #10
    Duke's Avatar
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    Vern, Green Hulk and VT.SE are very correct. The SC assembly is delicate at best and needs room for decel and movement for choppy water. This may play havov on tuning but is needed.

    The absence of the BOV actually helps slow the wheel down in decel and relieves some stress off the clutch,

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