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Old 04-19-2011, 11:53 PM   #1
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Default ITT: quiet BOVs/bypass valves

After doing a search I have come to the conclusion that:
-Not running a BOV is not an option.
-Recirculating BOV is quiet
-Recirculating may or may not be a bad thing and is only done on AFM cars. (pretty unclear on this, but MS so speed density)
-Taking a recirc BOV and venting it to atmo is just as loud?
-Spaghetti

I'm not into the whole WHOOSH thing. I feel like I belong in F&F. I'd rather it be damn near silent when I have to release pressure because, also, I don't want to attract the wrong kind of attention (cops). All I've gathered so far is that a Bosch recirc BOV is quiet.

Excuse the ignorance, but I don't know if a BOV and bypass valve is the same thing. If they are not, I'm not sure if a bypass valve is quieter.

Some education on the subject would be appreciated. Mainly:

wut bov is quiet and gud
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Old 04-20-2011, 12:02 AM   #2
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-Recirculating may or may not be a bad thing and is only done on AFM cars. (pretty unclear on this, but MS so speed density)

recirculating is done normal because MAF\AFM's meter air and releasing air after it has been metered throws off fueling calculations causing stumbles and other issues.
You have to recirculate if your bov is after the maf\afm.
If its before the AFM\MAF you don't need to.

-Taking a recirc BOV and venting it to atmo is just as loud?
I am using a stock rx7 turbo 2 diverter valve, its just as loud as when I wasn't running anything.

-Not running a BOV is not an option.
depends on turbo and pressure, ran my T3 fine with no valve for a while, no issues



You could try muffling the bov with a container of some sort
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Old 04-20-2011, 12:06 AM   #3
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there's no reason you can't run a recirculating valve on a MAP based system. It will work just as fine and be quiet.
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Old 04-20-2011, 12:11 AM   #4
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My TiAL Q is pretty quiet when the pressure is low.
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Old 04-20-2011, 12:56 AM   #5
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Quote:
Originally Posted by dustinb View Post
there's no reason you can't run a recirculating valve on a MAP based system. It will work just as fine and be quiet.
The problem with recirculating valves is that most of them are only 1 piston therefore they are open when in vacuum and allow unfiltered air to enter into the engine.

I am running a forge vent to atmosphere bov that i can barely hear. Wouldn't mind exchanging it for something louder of equal quality.

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Old 04-20-2011, 01:12 AM   #6
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Quote:
Originally Posted by triple88a View Post
The problem with recirculating valves is that most of them are only 1 piston therefore they are open when in vacuum and allow unfiltered air to enter into the engine.

I am running a forge vent to atmosphere bov that i can barely hear. Wouldn't mind exchanging it for something louder of equal quality.

That BOV is not what I would consider quiet.



You could use a Bosch bypass valve VTA and put a filter on it for idle situations. It is extremely quiet and only makes a "sigh". It's nearly inaudible when in recirc configuration too.
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Old 04-20-2011, 01:15 AM   #7
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Where do you have yours at? I have mine right on top of my IC and i cant hear ****. Just the turbo spooling sounds louder than the bov even when i let off the gas from 7psi.
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Old 04-20-2011, 01:17 AM   #8
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That was mounted just before the throttle body.
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Old 04-20-2011, 01:18 AM   #9
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Hmm I guess i'll flip my piping around and hope for some luck. You using those silicone T pipes? http://www.siliconeintakes.com/produ...3ec5ce6b7945d7

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Old 04-20-2011, 02:15 AM   #10
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bosch bypass valves from some audis are what a lot of VW guys use when they want to be stealth. and they hold boost into the 20's
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Old 04-20-2011, 02:24 AM   #11
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I'm not shitting you: Use an HKS SSQV. Just remove the whistle tips.
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Old 04-20-2011, 03:56 AM   #12
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****. So many ways to go about this. I may just do the recirculating BOV and try it in recirc and in VTA and see what I like.

So other than the unfiltered air situation, I should be fine just venting a recirc? Is there a specific place you guys are getting your Bosch BOVs or a specific type (obviously recirc)?

/ignorance
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Old 04-20-2011, 05:38 AM   #13
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you dont really need one though. It helps with boost response on gear changes, and at higher boost levels supposedly helps with turbine life, though thats yet to be proven.

Dann

Last edited by nitrodann; 04-21-2011 at 09:05 AM. Reason: Some of what i said was incorrect and the rest didnt come out how I meant it to.
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Old 04-20-2011, 07:35 PM   #14
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Quote:
Originally Posted by nitrodann View Post
a recirc valve is the same as a VTA valve in operation
Dann


Have you even seen a diagram of a bov?

After reading more of your post you seem to have some reading to do about turbo life.
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Old 04-20-2011, 07:49 PM   #15
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How do you figure it's not? The only difference is the pipe that routes back before the turbo, aside from those that have eleventy small holes instead of one large one.
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Old 04-20-2011, 08:30 PM   #16
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Quote:
Originally Posted by Jeff_Ciesielski View Post
I'm not shitting you: Use an HKS SSQV. Just remove the whistle tips.
What's the whistle tip? The purple part?

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Old 04-20-2011, 08:32 PM   #17
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Quote:
Originally Posted by kenzo42 View Post
What's the whistle tip? The purple part?
I'm so sorry but I can't resist.
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Old 04-20-2011, 08:32 PM   #18
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Quote:
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What's the whistle tip? The purple part?
No, the silver fins that are in the discharge port.
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Old 04-20-2011, 08:42 PM   #19
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i feel like i have seen one that was set up as if it would recirculate but had a filter on the end of the tube.. is there any way to attach pipe to the bov and route it to a filter.. i feel like this would cut down on the sound
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Old 04-20-2011, 09:14 PM   #20
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Quote:
Originally Posted by Jeff_Ciesielski View Post
I'm not shitting you: Use an HKS SSQV. Just remove the whistle tips.
Actually this is true. I had one on my Skyline and pulled the chrome thing out. Sounded like an nice woooosh after. But really low key.
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