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  1. #1

    Pump Pressure Relief Mod

    Here are a few pics of my setup.. Put a 1/8 npt barb at 10 and 2 oclock. Used jetworks pro valves, 2 transmission cooler hoses with the steel lines crimped on them, then ran the steel line through a homemade aluminum bracket that mounts to the upper left pump bolt. Aluminum bracket started life as a truck mirror bracket. It is much happier now going fast on a jet ski.
    The 2 oclock exit hose can easily be routed over to the 10 oclock side as the pic shows. A hose loom, bracket (not yet installed) will be installed using the rear 10 mm bolt from the exhaust exit and keeps the hose clear of any exhaust action.

    Riding today the valves opened between 40-45 mph. I set both the same and i was amazed at how much water shot out of them at hi speed. Handling was still very good with the FF j-plate, but the ski did seem to lift out of the water a little more, just had a lighter feel to it, but still would stay stuck and did great in a few 75 mph slalom zig zags, and not a hint of buck..

    Performance gain i cannot verify, i changed the impeller also and went a little to high, and wasnt in any flat water either..

    General consensus is ... I love it! It felt very fast, very light and very safe.. I think the days of pump tunnel cracking are gone and this should yield many benefits in both the speed and safety realm..

    Ross
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  2. #2
    Moderator RX951's Avatar
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    SWEEEEET ! thanks for sharing Ross ! This is great news. A breakthru I must say for the advancement of the GPR!
    I know you pioneers that have been working on this need cudos !



    this is now a Sticky !

  3. #3
    Robsauto2's Avatar
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    So did you tap into the 2" extention? I dont have that, so where would I tap into? Thanks

  4. #4
    Nice install Ross!!

    Just out of curiosity. You have your valves set to open between 40-45 mph, is this with a 800 or 1200 grate? I was thinking that a 1200 grate would open sooner than an 800 since it flows more water and at higher pressures. I know its easily adjustable but I was just wondering if maybe 40-45 on a 1200 grate would'nt be more like 55-60 on an 800? That still sounds good to me so you wouldnt loose any thrust that you could still use.

  5. #5
    Duke's Avatar
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    Good looking install Ross!!

    I think you will be very happy with the results after a little fine tuning. The boats Rich and I have done actually required the boat to be loosened up a tad to get the speed back. Rideplate angle can be taken to a complete different level.

    Pressure pop off doesn't seem to be that important. I've gone from 10 psi to almost 30 and it doesn't seem to make much difference as long as they open by 65mph or so.

    With you and Jim working on this I expect to see great gains from this camp. Unfortunatly I will be able to do any more for a while.

  6. #6
    (So did you tap into the 2" extention? I dont have that, so where would I tap into? Thanks)

    Yes it is tapped into the 2 inch extension... If you dont have one then i dont know where you would put the barbs. The 2 inch extension works very well.

    This is on my EFI 1390 lowell ski and it has an 800 grate. I will be installing the same kit on my other ski which has the 1200 grate soon..

  7. #7
    There is no VooDoo like BadVooDoo NeVerMind's Avatar
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    For those without the extension... Can a valve be added to the pump strainer? Have the one line go into the waterbox (jetworks mod) and the other as a pressure relief?

  8. #8
    My son (mohawk man) jeffsntx's Avatar
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    Quote Originally Posted by NeVerMind View Post
    For those without the extension... Can a valve be added to the pump strainer? Have the one line go into the waterbox (jetworks mod) and the other as a pressure relief?
    NO!!!!! Do not do this. The pump pressure must be relieved BEFORE the impeller housing. If you vented it in the strainer you could possibly starve the engine of the water volume that it needs to stay cool.

  9. #9
    Hydrotherapy's Avatar
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    Quote Originally Posted by jeffsntx View Post
    NO!!!!! Do not do this. The pump pressure must be relieved BEFORE the impeller housing. If you vented it in the strainer you could possibly starve the engine of the water volume that it needs to stay cool.
    does anyone know the stock cooling line working pressure, aprox.......

    then ross can measure his with mods to see if its being robbed top end of water..

    just a thought...

  10. #10
    My son (mohawk man) jeffsntx's Avatar
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    Paul, the way that Ross, WFO, Hydro and Duke are doing it, it does not have any affect on the water going through the strainer and to the engine, they are venting it in the 2" extention.

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