Factory Pipe Adjustment Screw Demonstration
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  1. #1
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Factory Pipe Adjustment Screw Demonstration

    I did this a few years ago when I was bored.

    Basically just connected a garden hose to one of the factory b-pipes I had in my stash of spares and simply compared the visible flow differences as I adjusted the bottom injection screw. I suppose I should have connected a flow meter to the feed line to be more scientific, but oh well. This did provide some decent info.

    Here is the starting point.

    20200905_112718.jpg


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  2. #2
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Step 1. Screw fully closed. As you can see, it doesn't completely stop the flow.

    20200905_112722.jpg


    WHEN IN DOUBT, GAS IT!

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  3. #3
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Step 2. Screw 1/4 turn open. Stream is steady but piddly.

    20200905_112803.jpg


    WHEN IN DOUBT, GAS IT!

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  4. #4
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Step 3. Screw 1/2 turn open. Noticeable increase over 1/4 turn.

    20200905_112810.jpg


    WHEN IN DOUBT, GAS IT!

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  5. #5
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Step 4. Screw 3/4 turn open. Similarly noticable increase going from 1/2 to 3/4 as was seen when going from 1/4 to 1/2.

    20200905_112817.jpg


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  6. #6
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Step 5. Screw 1 turn open. The increase from 3/4 to 1 was noticeable, but probably a tad less so than the previous increases.

    20200905_112823.jpg


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  7. #7
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Steps 6 and 7. Screw 1.5 then 2 turns open. Essentially, once you get past 1 full turn open, that's about it for the adjustment. No more changes in flow to be detected visibly or audibly.

    Yeah, this demo isn't super scientific, but it does at least show the adjustment range available with these screws.
    Note that I left the Allen wrench in the pictures, so you can see the adjustments as I went along.


    20200905_112831.jpg20200905_112837.jpg


    WHEN IN DOUBT, GAS IT!

    Yeah, I'm an @sshole, but I'm not a complete @sshole.

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  8. #8
    Top Dog JC-SuperJet's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Good to know. Thanks.

  9. #9
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    Quote Originally Posted by fox river pwc View Post
    Yeah, this demo isn't super scientific, but it does at least show the adjustment range available with these screws.
    Note that I left the Allen wrench in the pictures, so you can see the adjustments as I went along.
    A mistake in early dyno testing was using tap water pressure to
    simulate the cooling water supply from the 440/550 pumps. Flowing
    pressure from the tap is only 4 psi. The flowing water pressure supplied
    by the 440/550 pumps were ~30psi.

    I am trying to distinguish between flowing water pressure and static
    water pressure. Static tap water pressure can be ~10x the flowing
    water pressure, but it isn't usable.

    The average 750 has ~40psi (flowing water pressure).
    The average 1100 has ~50psi (flowing water pressure).


    Bill M.

    The early PJS pipe dyno tests (and possibly others) were at the lower
    (4psi) pressure, so on the dyno the pipes were dried out, and had
    hotter exhaust temps. When they under went first article testing
    the pipes had disappointing power because of the increased pressure
    and the cooler exhaust temps.
    Horsepower == Speed, RPM != Speed



  10. #10
    PWCToday.com Is My Home Away From Home fox river pwc's Avatar
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    Re: Factory Pipe Adjustment Screw Demonstration

    You're referring to dynamic versus static pressure.
    I'm familiar. For my real job I work on development, troubleshooting and operational training of multi million dollar RO water production and distribution systems used for watering drug research animals. We manufacture our own 316 passivated pressure regs from scratch ...even all the silicone components are molded in-house (as they need to tolerate aggressive RO and DI water with pH levels as low as 2.5 and free CL2 levels as high as 10ppm long term). As part of our distribution systems, we make pressure reducing stations, as we need 12-15psi dynamic for flushing the RDS and rack manifolds and 3-5psi dynamic for supplying our pivoting shielded drinking valves. Too much pressure to the valves means weanlings can't actuate the valve and they dehydrate. Too much pressure and we risk cage flooding and hypothermia. We are talking about mice that can be worth $10k+ each in the scope of drug studies that cost millions. We feed these pressure reducing stations with literally the same dynamic pressure and flow ranges that a well pump produces, and then knock the pressure down to 12-15psi with the first regulator, then down to 3-5psi with the second. We use a bypass solenoid in between them to be able to control which pressure level is sent downstream. Fun stuff.

    Anyhow, I get that a 440 pump is different than my well pump. The 40-60psi coming from my well and exiting out of the wide open end of a garden hose, at a consistent rate of flow and pressure, is different than a ski pump where the pressure and flow varies with pump RPM. However, the adjustment screws in the headpipe are nothing more than simple flow restrictors that require "x" amount of dynamic pressure and flow to effectively "max them out", as anything above that amount isn't getting past the restrictors/screws and into the headpipe. But yeah, dyno testing a pwc motor/pipe would be much more realistically performed with water supplied to a wet exhaust system that mimics what comes from an actual PWC pump versus a garden hose fed by a well pump.


    WHEN IN DOUBT, GAS IT!

    Yeah, I'm an @sshole, but I'm not a complete @sshole.

    http://badgerlandjetpilots.com/

    I don't come here to make enemies - only to identify them...

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