violacleff Posted March 14, 2006 Share Posted March 14, 2006 Hey guys, I was wondering if there was a test I could do to see if my bov is opening or not. James Thagard posted on zcar.com that the turkey under my hood was surging. There aren't any soundclips on the web for me to hear what my bov should sound like. What do u think? http://videos.streetfire.net/video/2...4A63D77757.htm I always thought a greddy R would flutter under low boost cause it shuts down harder than most bov which stay open longer. Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted March 14, 2006 Share Posted March 14, 2006 From what I've experienced with blow off valves is that if the spring tension is too great, then the valve will not open unless you are running high amounts of boost. It's a tradeoff of response vs. staying shut under high boost. If the spring tension is too loose, the blow off will open up under boost and cause a leak. From the Option Tsukuba Superlap videos I've watched, the TypeR blowoff valve on the Jun Lancer gets a little surge, but you can hear the pshhhh when it opens up if you crank the volume up a bit. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted March 14, 2006 Share Posted March 14, 2006 I can't watch streetfire.net videos, do you have a direct link? The only reason I could think of as to why a BOV would be forced open is if its positioned close to the turbocharger, and there is a large pressure drop between there and the inlet manifold. A BOV is a spring yes, but its not ONLY the spring that is holding it shut. The feed line to the top of the spring is connected to the inlet manifold, hence if the BOV is just before the T/B there is very little pressure difference between the top and bottom of the spring, not enough to open it. Then when the T/B slams shut the intake manifold goes to vacuum which helps open the BOV. Thats my understanding of the theory anyway, could be totally different in practise. Dave Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted March 14, 2006 Share Posted March 14, 2006 if the spring tension is very high.. with high amounts of boost.. the BOV will open and close, open and close very fast.. or a turkey call.. if the spring tension is very high.. and low amounts of boost.. the BOV will NOT open, and the turbo surge will result in a turkey call if the spring tension is very loose.. and high amounts of boost.. the BOV will open and stay open for quite sometime and will close slowly... so letting off the gas, and mashing the pedal immediatly will not build boost. also too loose, will BLOW the valve open under boost, and you will have boost leak Capeesh? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted March 14, 2006 Share Posted March 14, 2006 No, I don't capeesh. The spring is held shut by the pressure in the intake manifold. How would it possibly be blown open? Dave Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted March 14, 2006 Share Posted March 14, 2006 the BOV is BEFORE the intake manifold.. soo there is MORE pressure in the intake piping and the valve on the BOV than the pressure in the vacuum tube further downstream.. especially under low throttle situations... throttle partially open in 5th gear = boost .. more boost in the piping than in the intake manifold dont believe me?? why do people crush the DSM BOV to tighten the spring? the stock DSM BOV will blow open stock at 17-19 psi... a crushed DSM BOV will hold 25psi try an adjustable BOV like the Greddy Type RS.. and have it super loose.. and see how much boost you can run Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted March 14, 2006 Share Posted March 14, 2006 Yep, and thats a bad thing? I just thought it was normal, disappears as soon as you put your foot into it? Dave Quote Link to comment Share on other sites More sharing options...
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