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Thread: BOV Question

  1. #1
    FZS Monty's Avatar
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    Angry BOV Question

    So yesterday i ran my ski on the hose after installing B1, Power Cooler with HKS BOV, R2. Testing was done on the trailer, since its 30*F in NY, no water testing yet. WHY does the BOV work occasionally? IF i hold RPM's at 2 or 3K RPM and blip the throttle to 4k RPM i will hear and feel the boost coming out the BOV and if i do it again a minute later,.. nothing.... WTF? btw i have a dedicated vacuum hose running to the BOV from the manifold. help..


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    ksalles's Avatar
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    The BOV should be wide open on a charged application until you reach any boost. More than like you're spring is to tight and the vacuum you're making can't overcome the spring to open it. I'll copy and paste what commented on in another topic and hopfully it may help you. My ski has zero surge with the BOV setup properly.


    This was regarding my application on another topic....

    I'm not that surprised that the BOV works as well as it does. The 50mm Tial with the light spring actually is labeled as a surge/bov. What causes surge is when the the motor can't ingest as much as the blower puts out. When that happens, compressed air kicks back on the blower. Thats what you hear, basically the wheel trying to overcome the backed up air. This is probably the culprit in destroying the clutches in our skis. From what I gathered from Tial, the big BOV helps combat pumping losses at part throttle...usually in vacuum. This also helps keep the intake tract cooler from venting the charge into the atmosphere and not pumping unwanted boost into the intake relative to throttle position. This basically takes the load off the blower at less than WOT too. This possibly explains why the correct BOV/surge valve could be beneficial in our application. I wouldn't trust any other style valve with a high boost application...like the HKS etc. This is mainly because of the lack of volume they can flow in comparison to the 50mm valve by Tial.



    Quote Originally Posted by FZS Monty View Post
    So yesterday i ran my ski on the hose after installing B1, Power Cooler with HKS BOV, R2. Testing was done on the trailer, since its 30*F in NY, no water testing yet. WHY does the BOV work occasionally? IF i hold RPM's at 2 or 3K RPM and blip the throttle to 4k RPM i will hear and feel the boost coming out the BOV and if i do it again a minute later,.. nothing.... WTF? btw i have a dedicated vacuum hose running to the BOV from the manifold. help..

  3. #3
    FZS Monty's Avatar
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    Thanks a lot Ksalles, makes perfect sense. Too bad i leanr about it now, after it took me 2 hrs to install that Effin BOV onto the RIva cooler, talk about a pain in the ass.
    Question: once in the water, did you notice surge with other then Tial BOV's at less then WOT? is the SPring on my HKS Easy to swap out?.. would love to get rid of the surge...

  4. #4
    FZS Monty's Avatar
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    after a little research:

    http://www.motoiq.com/forum/aff/16/a...afv/topic.aspx

    sounds promising.. will attempt soon.

  5. #5
    ksalles's Avatar
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    There ya go...good luck with it. The spring tension and reference line (dedicated ONLY to the BOV) is very important when dealing with the blow off valves. The valve should be open at all times during vacuum and only close when the pressure behind the throttle plate, is anything above vacuum. During cruising, or anything out of boost, mine is wide open. Thats the way it should be to help with additional heat created in the intake tract when there doesn't need to be and surge kicking back on the compressor wheel. The spring needs to be soft enough to where as soon as boost is being built and gets past the throttle plate, the reference line signals the valve and equalizes the pressure inside the manifold to on top of the spring allowing full boost. Basically the system should only allow the amount of boost into the intake tract as the motor can ingest. Thats the whole point of these valves and what the key is to eliminate the surge. As soon as the boost lessens behind the throttle plate, inside the manifold, the valve should start releasing pressure with it to eliminate the compressor surge. Your valve should work fine once fine tuned. There is alot of misconception how the valve should work. Good luck with it and keep us posted. Don't stop until it does as I described...some settle and deal with compressor surge. You shouldn't have to once you get it dialed in.

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    FZS Monty's Avatar
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    Great! THanks! I will not ride it until its all dialed in on the trailer. I will video Before and after to post up back here.

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    Same thing happened to me when I installed mine. I started a thread on it here, and I was told to test it on the water with the engine under load. It worked fine.

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    FZS Monty's Avatar
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    great, ill do some water testing in march/april and get back to the post. First no changes, stock BOV, if surge persists, modify the spring..
    Thanks for the input buys.

  9. #9
    ksalles's Avatar
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    This is how your valve should work. When you think of the simple principle of how the surge/bov operates it makes sense why it should be open at idle all the way until the motor is ready to ingest boost..not just when it's made relative to rpm. The valve actuates as fast as the signal travels from the manifold to the top of the spring...basically opening and closing with the throttle.

    Quote Originally Posted by FZS Monty View Post
    great, ill do some water testing in march/april and get back to the post. First no changes, stock BOV, if surge persists, modify the spring..
    Thanks for the input buys.

  10. #10
    FZS Monty's Avatar
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    wish HKS would make a 3lb spring... so stupid..

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