ITT: quiet BOVs/bypass valves
They react different. Finally found the website with the cutaways.
http://www.evilution.co.uk/249
All the stock (such as bosch) recirculating ones are like the first one (either rubber diahram or a piston)
The 2nd one is the one with the 2nd piston and thats made to prevent crap from going back into your intake even when the main valve is open. Thats how most regular VTA are.
http://www.evilution.co.uk/249
All the stock (such as bosch) recirculating ones are like the first one (either rubber diahram or a piston)
The 2nd one is the one with the 2nd piston and thats made to prevent crap from going back into your intake even when the main valve is open. Thats how most regular VTA are.
That said, it doesn't work any differently than what you're calling a recirc bov. At any pressure above atmospheric the pistons are locked together.
Last edited by Asx; Apr 24, 2011 at 11:36 AM.

Its different when in vac and thats what i've been saying all along.
$1.19 from ace hardware is my solution.
Thread Starter
Joined: Aug 2009
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From: Redwood City, CA
Grah. I'll just run a rubber hose along the piping then if I decide to recirculate. I dont see a reason to run that crossover tube right in front of everything.
According to Begi their stock bosch valve makes a "silent sigh".
http://www.bellengineering.net/produ...roducts_id=126
http://www.bellengineering.net/produ...roducts_id=126
The synapse i've seen is loud. I'm pretty sure they have different models though.
Today i modified my forge and enlarged the holes. Now every small hole is connected to the big hole next to it. Still havent driven it so dont know what it sounds like but i'll post some pics and results when i drive the car later on.
Today i modified my forge and enlarged the holes. Now every small hole is connected to the big hole next to it. Still havent driven it so dont know what it sounds like but i'll post some pics and results when i drive the car later on.
Hmm, well we'll see. I'm too impatient - I went ahead and ordered one. Apparently the new model (SB002) is available on their website only, so I snagged it from there. Black finish to match my TB. 
I'll be running it with the 1.25" recirc fitting and a little filter, if I can find a decent filter that is. Having a bitch of a time finding a 1.25" ID filter.
EDIT - Nevermind: http://www.knfilters.com/search/prod...x?Prod=62-1512

I'll be running it with the 1.25" recirc fitting and a little filter, if I can find a decent filter that is. Having a bitch of a time finding a 1.25" ID filter.
EDIT - Nevermind: http://www.knfilters.com/search/prod...x?Prod=62-1512
Last edited by kotomile; Jun 25, 2011 at 04:27 PM.
Thread Starter
Joined: Aug 2009
Posts: 1,784
Total Cats: 42
From: Redwood City, CA
Thanks for the link, I was looking for the same thing in 1" ID.
Ended up getting a bypass valve from 034 motorsports. A little more expensive than the plastic bosch valve, and I read pretty good reviews from Euro guys who use it.
Ended up getting a bypass valve from 034 motorsports. A little more expensive than the plastic bosch valve, and I read pretty good reviews from Euro guys who use it.
I figured I'd bump this up and find out how the 034 valve worked out for MartinezA92, or if it was changed for some other solution. I'm thinking we have the same requirements for the same reasons.
Thread Starter
Joined: Aug 2009
Posts: 1,784
Total Cats: 42
From: Redwood City, CA
I ended up using the 034 BPV...and its vented to atm. I stuck a tiny filter on it and wrapped a couple socks around it and it was KIND of quiet. But for some odd reason this BPV sounds so cool when its vented that I took the socks off and stopped caring.
A+ would buy again for any application. No idea how quiet it would be when it's recirc'd
A+ would buy again for any application. No idea how quiet it would be when it's recirc'd
here you can find a couple vids.
New Synapse BOV Blow-Off Design Eliminates Compressor Surge - Video Dailymotion
They seem to have a myriad of adapters for their Diverter Valve (DV001x) or their Synchronic BOV (SB001x) to adapt them to recirculate. They even have a video on their youtube channel:
but dammed if I can tell the difference.
I've currently got a Bosch 710N in hand, but by all reports they are pretty budget and can't take a lot of abuse. The rebuild-able 034 Spec BPV is a direct replacement for my 710N, as is the FrozenBoost "SS Style BOV". They are probably both the same unit, but who knows.
Remember, I'm not looking for more flow or more boost, I'm looking for more quiet...er
but dammed if I can tell the difference.
I've currently got a Bosch 710N in hand, but by all reports they are pretty budget and can't take a lot of abuse. The rebuild-able 034 Spec BPV is a direct replacement for my 710N, as is the FrozenBoost "SS Style BOV". They are probably both the same unit, but who knows.
Remember, I'm not looking for more flow or more boost, I'm looking for more quiet...er






