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  1. #1

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    Bov closing slowly

    I have an hks style bov from frozen boost. The problem I am having is it seems to take 2-3 seconds to fully close after is discharges. Consequently, if I blip the throttle during this time it creates a massive boost leak from not closing. It seems too stay closed at idle and during boost.

    I am using a plastic tee for the vac line. I sprayed the bov with fluid film, but I'm still having the same issue. This is all on the hose. I have not had time for a water test if that makes a difference.

    What could be my issue?

    I have been told the frozen boost bov has been run without issues by many on the boards.


  2. #2
    abracadabra's Avatar
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    You need to get it to the water. These are sequential BOV and it will try to equate the pressures before and after the TB when the engine isn't pulling. To give you an example on my FZR the BOV closes shut on holeshot but as soon as I stay at cruise speed or slower around 4K rpms the valve may open just a little bit since the super charger is making more boost than the engine needs to operate at 4K. I hope this helps and look forward to hearing your results. Take care, Julio...

  3. #3

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    I will give it a shot. thanks.

  4. #4
    ksalles's Avatar
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    Spring pressure in the valve as well as reference line inside diameter play a role in how fast or slow the BOV reacts. I would suggest running 1/4" or 6mm line as your manifold pressure reference if you're not already. Also, the lightest spring you can use the better. The lighter the spring, the faster and more accurately the valve will open and close.



    Here is something from frozenboost that explains in detail directly how to select and set your BOV...
    (something striaght forward and simple I thought would help to share on this topic)

    1.Figure out how much vacuum your car is capable of pulling (peak vac). You can watch a boost/vac gauge while doing a high-RPM deceleration.
    2.Using the lightest spring, adjustment screw all the way out, and no shims/washers, install the BOV.
    3.Re-create your peak vac in your intake manifold. You may be able to use a vacuum pump or just let the car idle.
    4.If your BOV opens during peak vac, increase the spring energy. You can turn the adjustment screw to the right, install a heavier spring, install a second spring, or add shims/washers. Use caution when removing BOV top as the spring will try to throw the top in your face.
    5.Increasing the spring energy little by little in this way, you will soon find the point where the BOV is shut during peak vac. Make sure you hear no compressor surge during pressure relief.
    6.ALTERNATE METHOD: Let your car idle with the BOV installed with the lightest spring, adjustment screw all the way out, and no shims/washers. Using methods above, find the lowest amount of spring energy that will keep the BOV closed at idle. Since most cars pull more vac during deceleration, increase the spring energy by "some". We don't know how much "some" is because it varies from car to car, which is why we recommend the method above if possible. Make sure you hear no compressor surge during pressure relief.

  5. #5

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    Thanks. I am running a 6mm hose. it seems to open fine. The issue seems to be it takes forever to close, and if you gas it while it's open, it leaks all the pressure out.

  6. #6
    lets race.... mikeFZR's Avatar
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    IMO take the BOV apart and check for corrosion. It's really easy to disassemble, I've done it to mine to service it.

  7. #7

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    It's brand new out of the box. I took it apart to see what it's all about it looked ok as far as I could tell.

  8. #8
    PWCflorida.com FtLaudBlkGT's Avatar
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    Sounds like you have a binding issue, did you see if there was any binding with pushing the piston back and forth when you had it apart? Sometimes, there's just a defective one out there, I've had a couple that wouldn't open, and leak boost... They are mass produced so it's bound to happen sometimes.

  9. #9

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    I dont think binding is an issue. The BOV shaft slides easily when I take it apart.

    I will test ride after work. No one at the office seemed to notice I showed up late towing a jet ski and took up 4 parking spots.

  10. #10

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    Quote Originally Posted by abracadabra View Post
    You need to get it to the water. These are sequential BOV and it will try to equate the pressures before and after the TB when the engine isn't pulling. To give you an example on my FZR the BOV closes shut on holeshot but as soon as I stay at cruise speed or slower around 4K rpms the valve may open just a little bit since the super charger is making more boost than the engine needs to operate at 4K. I hope this helps and look forward to hearing your results. Take care, Julio...
    Thank you Julio you were correct. It operated as expected on the water. This ski is my first experience with boost so I am learning as I go.

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