An education lesson: BOV vs DV

[ADLER]

I see so many posts "BOV's = The DEVIL!!" So much disinformation that probably started as a way for the 3 or 4 companies providing aftermarket DV's to influence the market in their favor.

BOV: 2 types
type 1) closed loop system, i.e. recirculates the air back into your intake.

type 2) open loop system, i.e. vents the air back to atmosphere. Yes, the open loop can cause stalling problems, running rich problems, etc.

DV: 1 type
type 1) vents the air back into the intake.

Guess what, type 1 DV = type 1 BOV. there is no difference. A closed loop BOV will work the same in the A4 as a DV.

Some examples:

Closed Loop:

The Greddy Type-S BOV is a closed loop BOV just like the stock BOV with higher flow capacity and much stronger piston spring for no boost leaks.


TurboXS Valve H-34: closed loop.


TurboXS Valve H-25....wait a minute.... holy shit! what's this say from their website??? and I quote: "The Racing Bypass Valve Type 25 was specifically designed to replace the 1 inch (25mm) Bosch Bypass Valve used in most Volkswagen and Audi applications. The Bosch valve is prone to failure in stock application and not adequate for holding boost in "chipped" 1.8T equipped vehicles. The RBV-25 spring tension is adjustable, making it ideal for your modified vehicle."
How can this BE?! A "BOV" that was made for VW applications?! the world is ENDING!



DV's

HX Compact


Forge Valve


Open Loop BOV's - vents to atmosphere.

Blitz SS BOV:


HKS SSQ BOV


Turbo XS RFL


In Conclusion.
As you can see. The Closed Loop BOV is the same exact thing as the DV's some of you people worship.
The Open Loop BOV is different than a DV and yes, can be 'harmful' to your vehicle depending on your specific application.

BOV = DV = Bypass Valve

Feel free to flame away. I really don't care. I'm sure some of you still will refuse to see how BOV's can be the same as a DV just because that's what someone told you.

[F16HTON]

I heard that if you run a BOV that your car will throw a MIL, run improperly and it is just plain rice. Somebody also told me that the A4 is a European Luxury Sedan, similar to the Maybach, and BOVs do not belong on them.

[morgiea4]

Originally posted by 400HPA4
I heard that if you run a BOV that your car will throw a MIL, run improperly and it is just plain rice. Somebody also told me that the A4 is a European Luxury Sedan, similar to the Maybach, and BOVs do not belong on them.

I almost got a Maybach.. but I got a killer deal on my A4 so I opted to get it instead. I was going to get an S4, but hell I figured I could slap on 2-3 BOVs on my A4 and I would end up being just as fast for thousands less.

[QuattroRocket]

While I do understand your information above I an curious about one thing ... whats the point in a closed loop BOV ? If it recirculates the air then its a DV so why pay more for the horn setup if nothing is being vented ? And why call it a BOV if there is no air being "blown off" ?

[chelskisw6]

BOVs are ghey

[German Driver]

Whats the obsession with BOV? So you hear wooshing noise, BFG... Not like its your big turbo under the hood spooling. Closed circuit or not, people have thrown codes or worse case CEL. The idea is that it is kinda overkill. But with that said I look at a BOV as being a looks/hear thing. If you are more about modding the exterior on your car or more about making your car look aggressive then this is probably something you would like. It seems like something people do to make their car sound faster than it is.

[F16HTON]

Kinda like adding door blades

[German Driver]

Originally posted by chelskisw6
BOVs are ghey

you mean duck call BOV's aren't cool?

[German Driver]

Originally posted by 400HPA4
Kinda like adding door blades

Yea, just like adding door blades... actually no.

But if you kinda take more of the strong points im trying to make from my comment I think you will get a better understanding of where I am coming from. I am not saying everyone with a body kit feels this way, but rather that some people go with just exterior and nothing under bonnet.

[morgiea4]

Originally posted by 400HPA4
Kinda like adding door blades

If I remember correctly Greg... Dont u run a BOV? Guess you have nothing under the bonnet.

[German Driver]

Originally posted by morgiea4
If I remember correctly Greg... Dont u run a BOV? Guess you have nothing under the bonnet.

I believe he is just trying to play "BIG DADDY" to me because I made the comment. Kinda strange considering he is the unique individual who can back that whooosh up by some power...

[F16HTON]

Actually I hate the noise, but if I do not run one...I'll prolly toss the compreesor

[Nogaro A4]

Damn I wish you had of posted this like a month ago, when I did like 3 hours of research on the subject.
I just bought a hybrid DV/BOV, I dont feel that it compromises performance, and I like the noise it makes under full boost, I dont really care how anyone else feels about them.

[Itchy Foot]

Originally posted by QuattroRocket
While I do understand your information above I an curious about one thing ... whats the point in a closed loop BOV ? If it recirculates the air then its a DV so why pay more for the horn setup if nothing is being vented ? And why call it a BOV if there is no air being "blown off" ?

2nd that!

I thought BOVs = open loop and DVs = close loop

[JBM]

Guys personally I have run both a Bailey, Forge 007 and the Forge 004 BOV. I came to realize that the BOV felt like it held the boost better(I have GIAC 91 OCT File) and the fact that I run a carbonia system the air is not recycled. As for the rumors about the MIL I have not had one since installing it. I have VAGed my car and everything is fine. Say what you want to say its my car and it runs.

[Vortec4800]

Originally posted by 400HPA4
Somebody also told me that the A4 is a European Luxury Sedan, similar to the Maybach, and BOVs do not belong on them.

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHA! God, I haven't laughed this hard in a while. Good show.

[ADLER]

Originally posted by QuattroRocket
While I do understand your information above I an curious about one thing ... whats the point in a closed loop BOV ? If it recirculates the air then its a DV so why pay more for the horn setup if nothing is being vented ? And why call it a BOV if there is no air being "blown off" ?

Diverter Valve is just a different name for BOV... or BOV is just a different name for DV. I'm saying they are all the SAME, unless you have an open loop BOV.

It's like Shakespeare... 'a rose by any other name is still as sweet' or something to that effect.

I'm just stating that 1/2 the people here don't understand that a BOV = DV = bypass valve.

just because it's called a BOV doesn't make it open atmosphere. I don't understand why some people have difficulty grasping that concept.

a DV is the same as a recirculating BOV.

[ADLER]

Originally posted by Itchy Foot
2nd that!

I thought BOVs = open loop and DVs = close loop

DV = closed loop.
but there are 2 types of BOV's
they can come in either flavor, i.e. open loop, or closed loop.

[AB18]

Dude, if a bov is a closed loop system then its a dv, because if its a closed there is no air being vented so there is nothing being "blow off" why is that so hard to understand. But this is a nice post you started, prolly took you about 15min to put that post together, and it was a waste of time.

[ADLER]

Originally posted by AB18
Dude, if a bov is a closed loop system then its a dv, because if its a closed there is no air being vented so there is nothing being "blow off" why is that so hard to understand. But this is a nice post you started, prolly took you about 15min to put that post together, and it was a waste of time.

Apparently you have difficulty comprehending.
Take Greddy for example... considered a major aftermarket manufacturer.
Direct Link to Greddy "BOV"

Greddy Type-S, as my original post stated, is a "BOV" and it is "closed loop"

Or are you telling me you know more than Greddy?

It is accomplishing the same thing as a DV, because as I said a closed loop BOV is the same thing as a DV! Go back and learn to read. Here's what I said "closed loop BOV = DV = Bypass Valve"

I started this thread because everyone thinks they have to have something called a "DV" all I'm saying is that is not true. You can have a "BOV" as long as it recircs.

Here, I pulled the below from another site:

A blow-off valve is mounted in the intake plumbing between the
turbocharger compressor and the throttle plate. The blow-off valve is a second safety measure against the turbocharger over-boosting and damaging the engine.

The blow-off valve is more commonly used to keep the turbocharger spinning when the throttle plate is suddenly closed. When the turbocharger is generating maximum boost pressure at full throttle and then the throttle is suddenly closed, compressed air coming from the compressor slams against the throttle, generating extremely high pressures that travel backwards to the compressor stopping the compressor from pinning. When the throttle plate is again opened, the engine must spool the turbocharger shaft again. The effects of this high pressure can also be very damaging to the turbocharger.

the "BOV" can be closed loop, because it's still 'blowing off' the air, it's just blowing it back into the intake.

Let me guess, you don't believe that 'bypass valves' are the same thing either, do you? If it doesn't have 'dv' in the name it won't work.

[ADLER]

Originally posted by AB18
Dude, if a bov is a closed loop system then its a dv, because if its a closed there is no air being vented so there is nothing being "blow off" why is that so hard to understand. But this is a nice post you started, prolly took you about 15min to put that post together, and it was a waste of time.

Oops, sorry guys, I was wrong about something.
Guess, what... there are Two Types of Diverter Valves as Well

Since some of you believe it's impossible for a "BOV" to be closed loop, explaing this to me.... how about an open atmosphere diverter valve? Since Forge is a name that seems to be accepted and recognized in this community, tell me you can't have an open atmosphere Diverter Valve?

Atmospheric Diverter Valve

and I quote... from Forge:

Made from billet aluminium, this atmospheric diverter valve dumps the charge-air to atmosphere creating the "Whoosh" sound most commonly associated with rally cars when the throttle is lifted. This increases both quicker throttle response and higher clamping load to maintain boost pressure more reliably.

[AB18]

Dude, grow up, you knew exactly what i meant. A bov vents air, and Dv recirculates it, its not rocket science, its not a hard concept, call it what you want.



And btw- I am last person you need to lecture on cars.

[ADLER]

Originally posted by AB18
Dude, grow up, you knew exactly what i meant. A bov vents air, and Dv recirculates it, its not rocket science, its not a hard concept, call it what you want.



And btw- I am last person you need to lecture on cars.

All I'm asking is that you explain how there can be an atmospheric diverter valve then? see my previous post.
according to you, it's impossible. all I've been saying the whole time is BOV = DV = bypass valve

[bhvrdr]

Originally posted by ADLER
Oops, sorry guys, I was wrong about something.
Guess, what... there are Two Types of Diverter Valves as Well

Since some of you believe it's impossible for a "BOV" to be closed loop, explaing this to me.... how about an open atmosphere diverter valve? Since Forge is a name that seems to be accepted and recognized in this community, tell me you can't have an open atmosphere Diverter Valve?

Atmospheric Diverter Valve

and I quote... from Forge:

I think we all already pretty much knew this. You can run a BPV/DV in BOV mode and you can run a BOV in BPV/DV mode.
When people are referring to a BOV, they are generally referring to one venting to the atmosphere. For a factory like modified setup I cant see a reason to spend more than $50 to $100 for some of the highest quality BPV out there. cheers! Mike

[knight007]

OMG my car makes this loud WHOOOOOSH noise after I release the gas pedal......Holly my goodnesss....does that mean I have a blow-up valve??

Cmon guys, its your car so put a DV or a BOV in it if you want. It also doesn't make your car RICEY!!!??? Besides, if you hear an Import with that WHOOOOOSH sound that a BOV makes and wants to race you. You better be prepared for an arse reaming cause an Import w/forced induction is FAST!

[bhvrdr]

LOL...isnt an audi an import car? cheers! Mike

[ray-ray]

Originally posted by bhvrdr
LOL...isnt an audi an import car? cheers! Mike

lol yea it is. so many of us today just associate the term import with ricer wanna be JDM adn DSM cars out there on the stree. u know..those cars with the ungerglow lights that are too fast and too furious for us euros

[Itchy Foot]

Lets just say concept/idea of a DV and BOV is the same. I'm not saying they are the same thing because I don't see any other forum refer the BOV and DV are the exact same thing. Besides seeing it on forums I don't think they are the same thing.

On THIS forum we all refer to BOV as opened loop and DV as closed loop. End of thread.

[German Driver]

Originally posted by knight007
OMG my car makes this loud WHOOOOOSH noise after I release the gas pedal......Holly my goodnesss....does that mean I have a blow-up valve??

Cmon guys, its your car so put a DV or a BOV in it if you want. It also doesn't make your car RICEY!!!??? Besides, if you hear an Import with that WHOOOOOSH sound that a BOV makes and wants to race you. You better be prepared for an arse reaming cause an Import w/forced induction is FAST!

Who's Holly?

[F16HTON]

Originally posted by Itchy Foot
Lets just say concept/idea of a DV and BOV is the same. I'm not saying they are the same thing because I don't see any other forum refer the BOV and DV are the exact same thing. Besides seeing it on forums I don't think they are the same thing.

On THIS forum we all refer to BOV as opened loop and DV as closed loop. End of thread.

What about bypass valve?

[bhvrdr]

Originally posted by 400HPA4
What about bypass valve?

*bangs head on desk* I had a feeling this would become a very long and very useless thread. LOL. People are going to buy whatever the heck they want. Greg is one of the few here that has a reason to run a BOV. cheers! Mike

[Itchy Foot]

Originally posted by bhvrdr
*bangs head on desk* I had a feeling this would become a very long and very useless thread. LOL. People are going to buy whatever the heck they want. Greg is one of the few here that has a reason to run a BOV. cheers! Mike

yeah I know what you mean.

like this?

What about by pass valve? it is something you only need when you want to do all wheel burnouts....j/k.

[knight007]

Can we have both BOV and DV?

[AudBoost]

Originally posted by knight007
Can we have both BOV and DV?

http://www.gofastbits.com.au/index.p...ion=stealth_fx

[German Driver]

529.00 AUD Australia Dollars = 412.18 USD United States Dollars

It is beyond me why any individual would want to pay that amount for something you can get as low as $29 (710N) and have it perform just as well...

[F16HTON]

For whatever it is worth, the Bosch DV is a cheap piece of plastic junk. It is unable to handle ANY increased boost pressure for a proglonged period of time.

[bhvrdr]

Never blown a stock one on 21psi. Never blown a sport 110 on 23 and 26psi spikes and 21psi holds. Figure about 50K miles between the two. cheers! Mike

[F16HTON]

It is all the pressure drop from your DSMIC

[Mark]

this thread went south quickly.

[German Driver]

Originally posted by 400HPA4
For whatever it is worth, the Bosch DV is a cheap piece of plastic junk. It is unable to handle ANY increased boost pressure for a proglonged period of time.

I cannot justify spending $200 let alone almost $500 on a friggen DV/DOV/BPV whatever it may be. it is purely UNECESSARY.... (for avg. driver setup)

But not like my two cents is worth a dime around here...