blow off valve

**efx1** · 03-02-2012 09:52 AM

Who makes the best blow off valve for our Audi A5?

best pricing?

**gd10** · 03-02-2012 10:22 AM

Originally Posted by efx1

Who makes the best blow off valve for our Audi A5?

best pricing?

why would you want a blow off valve for the A5?

**efx1** · 03-02-2012 10:25 AM

heard it on another members car
sounds pretty good

http://www.youtube.com/watch?v=3ViWSy6YNcM

**mr shickadance** · 03-02-2012 10:52 AM

it's a bad idea, the sound i will be honest, does sound kind of cool i guess. but the b8 a5 2.0T engine was designed for a closed loop system, meaning that the ECU was programmed to accept and adjust it's A/F ratio based on the assumption that the 'blown off' air was going to be recirculated back into the intake manifold.

by using a blow off valve, you are intentionally making your car run rich, and you could stall out on occasion. the best bet is the factory DV, but if you are hell bent on getting that woosh sound, see if forged racing makes a DV for this car....i'm too lazy to do the research on it but i would assume they have a mechanical spring DV, that will give you a similar noise but much muffled, but still louder than stock.

**gd10** · 03-02-2012 11:03 AM

Originally Posted by efx1

heard it on another members car
sounds pretty good

http://www.youtube.com/watch?v=3ViWSy6YNcM

sounds good maybe, but decreases performance

**TGreene09** · 03-02-2012 11:23 AM

Originally Posted by gd10

sounds good maybe, but decreases performance

Diverter valves have been shown to not decrease performance. This has always been a hot topic though. And I agree you dont need a blowoff valve on a A5. Had one on a B6 A4 because and only it was recommended by APR to replace after an ECU upgrade. The 1.8T for some reason came with a weaker unit.

**mxrz** · 03-02-2012 11:45 AM

A blow off valve will work great once you add two large bottles of NAWZ.

**mxrz** · 03-02-2012 11:47 AM

Originally Posted by TGreene09

Diverter valves have been shown to not decrease performance.

Stating the obvious here, since the car already comes with a diverter valve.

**mr shickadance** · 03-02-2012 12:05 PM

i think the guy was trying to say that the BOV decreases performance

**bknewtype** · 03-02-2012 12:20 PM

why bov? because racecar

**mr shickadance** · 03-02-2012 02:18 PM

why bov? bc op clearly needs to be fast AND furious at the same time

**elf_cruiser** · 03-02-2012 02:28 PM

Originally Posted by mr shickadance

why bov? bc op clearly needs to be fast AND furious at the same time

"Granny shiftin' when you shoulda been dubble clutchin' ..."

**Okan509** · 03-02-2012 02:32 PM

This sub forum blows

You can direct serious questions about the A5 to the A4 section, where people aren't so ridiculous.

Or search, BOV's do not decrease performance, or increase it. They simply add the queef noise. There are a few different manufacturers with them.

**zxsuxr** · 03-02-2012 02:38 PM

Originally Posted by Okan509

. They simply add the queef noise.

Yea, thats why i dont run a BOV, queefs are a big turn off

**eclimax13** · 03-02-2012 04:01 PM

Originally Posted by Okan509

This sub forum blows

You can direct serious questions about the A5 to the A4 section, where people aren't so ridiculous.

Or search, BOV's do not decrease performance, or increase it. They simply add the queef noise. There are a few different manufacturers with them.

once again you add terrible advice and information to this forum.

To the original poster, you want to, at the most, look at hybrid diverter/bov's. Running a pure bov on a recirculating engine is not recommended and possibly can cause damage. There are those running them that haven't had a problem but I wouldn't risk something happening just for the sound. Another alternative is to get a less sound suppressive intake and you'll be able to hear the diverter valve, which sounds like a bov, but not as loud.

**MonzaA5** · 03-02-2012 04:36 PM

Originally Posted by efx1

heard it on another members car
sounds pretty good

http://www.youtube.com/watch?v=3ViWSy6YNcM

Buy an electrical teapot and a 12V adapter. That way, you can get the same sound without the performance decrease. And as an added benefit, you can have tea when you get thirsty..

**TofuShop** · 03-02-2012 04:49 PM

looks like they have a custom setup in that video because that is not the location of the stock dv. if you want a bolt-on solution, Forge makes one with an electronic connection that functions the same as stock (open/close via ECU, not vacuum operated):
http://www.audizine.com/forum/showth...lve-(FMFSITAT)

**mr shickadance** · 03-02-2012 04:50 PM

Originally Posted by eclimax13

once again you add terrible advice and information to this forum.

To the original poster, you want to, at the most, look at hybrid diverter/bov's. Running a pure bov on a recirculating engine is not recommended and possibly can cause damage. There are those running them that haven't had a problem but I wouldn't risk something happening just for the sound. Another alternative is to get a less sound suppressive intake and you'll be able to hear the diverter valve, which sounds like a bov, but not as loud.

quoted for all of the truths

okan - stop giving out misinformation

**Okan509** · 03-02-2012 06:11 PM

Originally Posted by mr shickadance

quoted for all of the truths

okan - stop giving out misinformation

What I said was in fact true. I recommended a search as well. For all the information on this topic that has already been discussed, What I said was supposed to be a short throw of info, which was not wrong. It was specific, but it wasn't wrong. So fuck off

**mr shickadance** · 03-02-2012 07:08 PM

blow off valves vent to atmosphere, your car is programmed to work with a recirculating or DV.....by doing this you ARE running your car rich, today's cars can adapt to it, but that takes time and you are still running the car rich,....care to guess how that affects performance?

stop giving out misinformation

**MonzaA5** · 03-02-2012 07:36 PM

Originally Posted by mr shickadance

but that takes time and you are still running the car rich,....care to guess how that affects performance?

Actually, a spark ignition engine produces peak power with a slightly rich mixture.

**Okan509** · 03-02-2012 09:25 PM

Originally Posted by mr shickadance

blow off valves vent to atmosphere, your car is programmed to work with a recirculating or DV.....by doing this you ARE running your car rich, today's cars can adapt to it, but that takes time and you are still running the car rich,....care to guess how that affects performance?

stop giving out misinformation

you're talking about 1 option out of 3 or 4 that are currently being made. Once again fuck off

**32spoke** · 03-02-2012 10:38 PM

okan, he's kinda right, you need an ecu modification to comprehend the change made to how the A/f mixture gets altered. otherwise it will make a recovery, but will take longer and creat a rich condition. it might make the sound you desire, but it WILL reduce the power until the ecu picks up a rich condition from the O2 sensors. but this is the internet, everyone will get nasty so try to take the positive out of what was written and do what you'd like!! and enjoy your car, cuz it's your car!

**mr shickadance** · 03-03-2012 04:32 AM

Originally Posted by Okan509

you're talking about 1 option out of 3 or 4 that are currently being made. Once again fuck off

a bov that also recirculates could be an option, but im pretty sure you need a DV relocator as the DV on the stock ko3 is on the housing, i don't think im being a jerk i'm just saying, stop giving out misinformation, it does affect performance, how much? not much, but it's not right to say that a BOV on an engine system designed to run closed-loop is proper and won't cause performance loss

**Okan509** · 03-03-2012 05:07 AM

I'm obviously not being specific enough. BOV's in my case include Any type of Diverter valve, or Blow off valve. Generally what you are saying is correct, but every car is different, and I feel like you are take the general and putting in to a specific car.

Anyway this is the info I found on the topic

Originally Posted by Info@EuroCode

The car will not run rich if you vent to atmosphere, this is an Internet urban legend. It is not like every molecule of air is inventoried and accounted for as it passes across the mass air flow sensor.

The exact same jibberish could be argued that venting back into the intake will cause the car to run lean since the air was counted once and was expected to be burned, but since you closed the throttle plate the air never made it into the cylinders.

Originally Posted by 400HPA4

This post is full of misniformation...first off there are no Carbonio intakes for the B8 A4, second, Forge does not make a true diverter valve for the B8 A4...

What is available for the B8 A4 is a Forge DVFSIT, it is a spacer that allows you to retain the factory diverter valve and instead of dumping the boost back into the intake tract, some of the boost gets diverted into the atmosphere, by doing this you get the whoosh sound that folks that own turbo cars like.

Is this childish? Depands on to who is listening I guess, there is no real answer to the question other than bee a free thinker, and do what you like to please yourself.

Of course, everyone has an opinion, some we agree with, some we dont...

Originally Posted by cory_can

Geez....tough crowd. If you want the sound the best advice came from 400HPA4 when he mentioned the DV Spacer instead of a full BOV. Audi's system is 'closed loop' and requires the excess boost to recirculate in order to be monitored......not to blow off into atmosphere. If you run a full BOV you'll have air/fuel mixture issue which will cause other problems.

Originally Posted by b6onboost

Audi's run MAF sensors and the air is metered. They use closed loop systems with a Diverter Valve, which vents boost pressure back into the intake post MAF. So if you run a BOV the air is being vented out of the system, yet the ECU still assumes its there, so it still pushes fuel. The air/fuel ratio is off and you run rich.

However, you only run lean for a second between shifts when the BOV releases. Under boost (acceleration) the BOV is closed and the car runs at the correct A/F ratio.

So it's not automatically bad, but it isn't optimal. I personally think it's ricer to have a brand new B8 and have that high pitched BOV sound. If you want sound, get an intake and the DV will make a nice 'whoosh' sound.

^like you said BOV bad, DV ok.

Originally Posted by LB_NY_B8

This Spacer Allows some of the air to be vented to the atmosphere when the throttle plate closes, it is perfectly harmless. There is no compressor surge.

"A DV and a BOV basically do the same thing, they release built up air pressure when the throttle plate closes, by releasing the air pressure, the turbo is able to stil spin freely. The reason that the air pressure is "diverted" back into the intake tract is because current emission rules do not allow it to be released in the atmosphere"

This is all as per eurocode.

Originally Posted by JMG

The desire to use a BOV for the "psst" sound on an Audi A4 has dated back to the B5 A4, and that debate has been restarted with each new generation of driver and build. Generally the use of a BOV on a close to stock Audi has been frowned upon because the A4 has been a closed system which utilizes a DV as opposed to an atmospheric BOV. Even some BT Audis don't need it.

I suggest doing some research on what a BOV does and what types of systems they are good for. Then determine where your car's (the B8) MAF takes it's measurement, if its an open or closed system, and what kind of gains you will get as well as the risk factors for using a BOV on your car.

What does an MAF do? On the B5-B7 A4 the MAF metered the intake air mass. This measurement is used to calculate the required fuel to be injected in order to maintain a proper air/fuel ratio. Because air mass reading is taken from the intake, venting air after the intake makes this reading inaccurate.

What does a BOV do? It releases excess air when the throttle plate is closed so as not to cause excessive stress to the turbo. When a BT setup running lets say 20-30 psi, experiences pressure surges, this can significantly affect the time needed to "re-spool" the turbo, cause premature wear and tear, and even cause damage to the turbo and blowout. Thus, the BOV is used on high performance big boost cars which have been tuned to adjust for the air released by a BOV. For those that know what a BOV does and where it is needed, the sound is associated with highly modified turbo cars. For others, it just sounds cool. Or maybe it sounds cool because we have heard fast cars make that sound?

Why didn't the A4 already come with one if it works so well? I'm not too sure, but the fact that the A4 uses a "closed" system is either a result of or one of the factors of using a DV instead of a BOV. Either way, the MAF and ECU were designed with a closed system in mind.

Note that there are also "spacers" which allow for the BOV sound while still being able to use a DV. The Spacer still makes the system atmospheric, venting air that was measured by the MAF. While some spacers are adjustable, they are still venting metered air.

One such spacer is made by Forge Motorsport, who expressly state that:

source: http://forums.vwvortex.com/zerothread?id=2651617

To summarize, the B5-B7 A4 was not designed to use a BOV or Spacer. The Spacer, which when used in conjunction with a DV, vents metered air, thus providing BOV functionality. The spacer/BOV has not been shown to improve performance in the 2.0T FSI and the manufacturer makes no claims that it will. Thus the BOV almost purely cosmetic for the B5-B7 engines with the stock KO3 running 8-9psi.

What's wrong with a purely cosmetic mod? Nothing. But I do have the opinion that a mod should not misrepresent or give false impressions of the car it is placed on. This would include such mods as false badging (ie S4 badges on a A4, Turbo badges on a NA car) and fake BOV generators such as this:

Fake Turbo Sound Whistler

The Fake Turbo Sound Whistler does not hurt or increase performance. It's purely cosmetic and a complete misrepresentation of the car it's placed on. I wouldn't say that a BOV on a stock A4 is as much of a misrepresentation or nearly as reprehensible. But, taking into consideration that the BOV is designed for big boost turbo setups running, for example, 20-30psi, it is my opinion that the BOV would be a misrepresentation of my vehicle unless I am actually generating those kinds of numbers. There are those who think it's fine to make others think that their vehicle produces the boost levels that require the use of a BOV when they, in fact, do not, but I am not one of them. On the other hand, there are those who don't even know what a BOV truly does or when it is needed, so there is no misrepresentation at all. The sound is just "cool". IMHO that does no service to the enthusiast crowd as a whole, because the entire meaning of the mod is closer to being lost to nothing more than a cosmetic sound. I don't know about you, but that doesn't sound like the ideal way to promote the community.

In the end, you make your decision. What is important to me may not be important to you. Take as many facts you can into consideration when you make your decision, and know that not everyone is going to agree with your decision or appreciate your mods, and they may have a good reason in their own mind.

Consensus, Get the DV spacer, which gives you the same whoosh, without the BOV run rich situation. I think there are 2 actual BOV's made for this car, and 2 DV's amde for our cars. SO that's what I was talking about ^.

Hope this is specific enough. And finally not "misinformation". I won't give out any info if I don't have anything to stand on. I usually give out good information. And I said to give it a search. When you search BOV - you get all the DV answers you need, because it's the same part, but doing slightly different things.

For what's it's worth a BOV is recommended when modding, but for the most part we want to be running DV's instead.

**eclimax13** · 03-03-2012 06:35 AM

Okan. You are so confused, it's scary.

**Okan509** · 03-03-2012 06:38 AM

Originally Posted by eclimax13

Okan. You are so confused, it's scary.

I posted things on both sides of the argument? is that why? I must be, since I have no idea what you're talking about.

**mxrz** · 03-03-2012 08:01 AM

This thread was about "blow off valves", not hybrid systems like the Forge spacer. The reason the Forge spacer works without any issues is because it retains a DV (any pressure release valve would do) that can be controlled by the ECU, through the MAP sensor (though I believe it is mounted before the manifold, so it's not a true MAP). Venting to atmosphere is not a problem, it never has been, but regular BOVs cannot be properly controlled electronically, and that is what causes potential fuel trim issues that can decrease performance. As long as the operation of the valve can be electronically controlled by the ECU, as required, there is no problem with venting and making that gay sound all the posers love

**oohnoo** · 03-03-2012 08:38 AM

Just about all BOV's can be had in both circulating and also be able to blow off to atmosphere. Every car is different when you blow off to atmosphere, some have issues and some don't. Same make/model can have two different results, seen it happen.
A good after market BOV will not leak or break down over time. And most important it will hold the boost and not bleed off.

Here's one made for the Audi A5 2.0
http://www.forgemotorsport.com/conte...oduct=FMFSITAT

The one in the vid looks like Tial BOV which is a high quality piece, I got one in my 3000GT

**efx1** · 03-03-2012 04:01 PM

Thanks oohnoo for the link

Here's an A5 with K04 turbo upgrade with blow off valve

http://www.youtube.com/watch?v=f3x3yfUZTDE

Sounds great !!!

Nothing ricey IMO

**mxrz** · 03-03-2012 04:44 PM

Originally Posted by efx1

Sounds great !!!

Nothing ricey IMO

Yeah, it sounds like a BOV, what did you expect... Everyone knows what it sounds like, and that has never been the issue. The retarded part is the whole concept of defeating a more modern and sophisticated system by converting it back to a more primitive system with no benefits what so ever. Would you also like a carburetor for your 2.0T? Or how about a non-synchronized manual transmission... yeah, didn't think so.