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Is there something wrong with my Tial BOV?

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15+ Year Contributor
Aug 8, 2004
Long Island, New_York
I just installed my brand new Tial 50mm BOV with an 11psi spring. A couple of things I noticed. 1 thing is the BOV makes barely any noise. I know its supposed to make a nice loud *BOP* type of noise. Im like WTF? It sounds like it does a mini compressor surge and then a little hiss. Also, my vacuum use to sit at 20hg/in at 750rpm. Now it sits at 17-18 at 800rpm. Anything would be helpful.
first thing to do is check for boost/vacuum leaks..
i'm not familair with the tial bov's in particular but it sounds like you need to tighten the spring
I think i need a looser spring. It sounds like its not opening all the way like it should. It surges alot meaning the spring pressure is too tight/ high.
if you are only running 18 psi, then you need to put a lighter spring in there. your BOV is causing compressor surge. put in a 7 psi spring and you should be fine.
I just ordered the 7psi spring. Now, I know I need an allen key to remove the top half. What do I need to do to remove the old spring and replace it with the new one? Thanks for the help.
Is it safe to run a 7psi spring on stock cams? Or should I go with the 9psi spring? 11 is way to hard for me. Thanks.
Alright first the tial in general is a pretty quiet BOV. The valve is 50mm its fricken huge. So to replyu to your first "problem" why did you get a tial if you wanted noise. Next getting the lower psi spring will probably allow the bov to open more, but from your mod list your turbo should be more than enough to open the valve. Once you hit 20psi+ the tial will be much louder and make a more "BOP" noise. what bov did you have before. The bov can change your idle vacuum. and check for leaks.
it's quiet (when recirculated?) or are you running blow-thru?
My last BOV was a HKS SSQV. My problem is not really the noise anymore, for now I actually broke it in and it makes some decent noise now. Not too loud, not too low. But what I am having problems with, and im not sure if it is it, but from 0-10 psi, its sounds as if its surging my turbo. The HKS SSQV surged the 3065 so much, that now I have shaft play, but not anywhere close enough to need a rebuild. I heard that they said that 9psi spring would be safe to run on a stock cammed 4G63t due to the fact of some surging issues. Anymore info would be greatly appreciated.
i take it back. tial can only be vented, not recirculated. i am teh dumb. :coy:
so man...did you solve anything with the BOV? I'm having some issues with mine now...when I had scm61 it ran fine, now it''s surging with a smaller turbo. I had a 11 psi spring and I put a 9 psi one...helped a little but it's probably too much for stock cams...the bov is half open at idle...and if I accelerate the car to 2k and let off the throttle it will open it's working. I changed the vacumm source...nothing, changed the vacum line to 3/16"(smaller) nothing...only thing coming to my mind now is lowering the lower IC pipe to 2.25"...I have 2.5" ...lowering the volume of air that the BOV throws out should help...ohh...I also noticed the valve was sticking a bit on the seal (o-ring)...not anymore with a bit of petroleum jelly :thumb:
I'm running a Holset HX-35/40 and need to boost to 25psi but NOT get surge at lower boost/part thrlttle. If TIAL is the best and you guys are having trouble i don't knoiw what to do!! Their site has a chart for choosing spring based upon vacuum at idle and with my cams I get 12" which calls for a 7# spring,comments? Van I run 25psi and not surge? I sent a question to tial but no response yet. Mark
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