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Choosing a blow off/ diverter valve.

12192 Views 19 Replies 13 Participants Last post by  NorthSide_pimpin18t
I have had my passat for about two years, and I am now looking for a blow off valve. Does anyone have any opinions on which is better? Also what are the pros and cons of each, is there a brand that is best? I was thinking Greddy, or HKS bfv. Any info is appreciated, thanks.
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Hmmm...doesn't a blow-off valve make you run richer? What engine (AEB, AWM) and year do you have?
Blow off makes it run very rich.

Quick explanation: Maf reads amount of air, engine gives it gas according to amount of air then *WOOOSH* the air that the maf read is gone and the engine still thinks it needs that much gas. BOV's let the air out into the atmosphere. With a DV, the air is recirculated and its at the should be proper air fuel ratio.

But there are some recirculating BOV's. Looks like a DV but has a flared horn on it. I haven't really heard many testimonials about them, but they exist.

Most people will tell you to get a DV (I hope at least lol) Personally I got a Forge 007 DV while planning to mod in the future. But if you don't really have any mods or plan on it then the 710N DV from the TT will work great for you
response

thanks for all the info. I have a 99 passat with the 1.8T and 5 speed. Someone told me that the Audi TT unit fails prematurely. Has anyone had any experience with either of these?
the Audi TT unit fails prematurely.
The Audi TT DV is what a lot of members have replaced their OEM DV with...holds sturdier. The OEM one fails prematurely.

OEM DV < Audi TT DV < Bailey or Forge or APR
Tons of a4 1.8t owners run the TT valve on their stage one chips. Holds up pretty good from what I hear
^ yea.

I've heard of many people using the TT DV with a chip. Most people upgrade to Forge or APR with a BT or something crazy awesome lol
New Information

Ok so sorry for the slow response, but I have been doing a lot of research on this issue. Apparently there are two other options besides using the factory Audi TT diverter valve. The first is a blow off valve by AgencyPower. They make a blowoff valve that is specially made for the 1.8L passat. Supposedly it recirculates 50% of the air back into the system, and sends the other 50% into the atmosphere. The other option is a Bypass valve by Turbo XS I have posted the info on it below. "Racing Bypass Valve Type 25 (RBV-25) US$169.00


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. This RBV-25, though louder than a stock bypass valve, is not loud compared to an atmosphere BOV." This info was taken from
"http://www.turboxs.com/shop_car6.php?car=11"

Also here is the info for the Agency Power BOV
Agency Power Passat Audi VW Blow Off Valve Kits
Photo may differ for each model

Agency Power turn to its design team to produce the first multi function and fully adjustable Blow Off Valve for the VW, Audi, and other vehicles using a 1 inch inlet and outlet flanges. Keeping the turbo spooled between shifts, holding boost pressure strong, and giving you adjustability is what the all new Agency Power Blow Off Valve offers you.

What makes the Agency Power Blow Off Valve above all others? The AP BOV is made in the USA and designed from the bottom up after analyzing the current market competitors. What we designed was a full T6061 CNC aluminum valve. The sleek body has a smooth round surface anodized with rich stylish colors in Stealthy Black and Rich Red. The Agency Power text is engraved on the body next to the 50/50 vent plate. The outlet flange is removable and can also work as a full vent to atmosphere position. The base is 1 inch in diameter and designed to be used with the factory hoses in the factory position. The brass nipple on the side is ridged to ensure the vacuum hose stays secure and has no leaks. Continuing with style, the top of the valve has the trademark AP logo engraved on the triangle style top which adjusts the valves spring load. This is held in place by a diamond cut lock ring and O ring. The inside of the valve is operated with a piston and steel spring. The spring rate is manufactured to the correct rate for stock to aggressive boost levels. There is O rings inside to provide proper movement and sealing.

The Agency Power BOV is a fully adjustable, fully rebuildable, and a completely useful device. The BOV is designed to be used with several different setups. The valve can be set up to vent 100% to the atmosphere or 50/50. This is where 50% of the air is returned to the intake pipe and 50% is vented out. As well, this valve can be setup as a 100% recirculation valve like stock. The valve includes the return line plug as well. We recommend this valve for daily drivers to high boost race cars.

http://www.horsepowerfreaks.com/pri...ncy_Power/Blow_Off_Valves/Blow_Off_Valve_Kits
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hmm...

so you're willing to spend that much for what, the sound of the blow off valve?
i wanted the sound of a bov, but went with a evoms diverter valve and i love it.

running a bov will make you run really rich, sluggish performance, and super bad fuel economy
stay away from any bov.
and if youre not planning on chipping anytime soon, the audi tt dv should work great.
but if you are chipping in the near future definately get a forge or apr or Evom diverter valve!

just my two cents
:)
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A tt DV will work just fine for a chipped 1.8T. Remember, it's made for the 225HP 1.8T in the older TT's
i was looking at the Forge hybrid DV. Because i need to get a new DV but i dont want to run rich but i want the sound of a BOV so i was thinking of this being a happy medium. Anyone run these?? and if so good or bad. anyone have any opinions on this?? Thanks

http://www.mjmautohaus.com/catalog/...irculating_Polished_Splitter&products_id=2593
i was looking at the Forge hybrid DV. Because i need to get a new DV but i dont want to run rich but i want the sound of a BOV so i was thinking of this being a happy medium. Anyone run these?? and if so good or bad. anyone have any opinions on this?? Thanks

http://www.mjmautohaus.com/catalog/...irculating_Polished_Splitter&products_id=2593
interesting! i would def be curious how these things run.
Technically.. you can put a bov on them..
but you have to run with no cat .. thats the only problem is that you run so rich that you risk blowing out the cat..
thats it..
just the cat...
make the engine free flowing and either manually or electronically tuning it..
a cat is cheap..
^ I'm going to go out on a limb and say thats probably 100% incorrect . Cats are not cheap, unless you get them used. Also running a BOV will give you a cel and cause your maf to freak out. Also, you would need to plug the hole in your tip. Also, depending on year, by manually tuning it, you run a high risk of bombing your turbo and engine. Don't mean to blow up your spot or anything, just sayin. Also I'm in denver as well :thumbup:
i was looking at the Forge hybrid DV. Because i need to get a new DV but i dont want to run rich but i want the sound of a BOV so i was thinking of this being a happy medium. Anyone run these?? and if so good or bad. anyone have any opinions on this?? Thanks

http://www.mjmautohaus.com/catalog/...irculating_Polished_Splitter&products_id=2593
I have been running one of these for over six months with no problems. Great sound, great performance and no check engine light! the other nice thing about the forge hybrid DV is that the spreing tension is adjustable, so there is no need to fool around swapping springs.
This may sound weird, but I re-routed my DV (actually, it's just a BOV with a 3/4" hose attached that spits the vented air just after the MAF) putting it right before the TB. Also, I installed a CAI and a FMIC.

Now, when I installed the CAI I heard that BOV loud and clear. You can also hear turbo hiss as well. Sounds great.

I should note that I am using a knockoff BOV, but it works great. Spits at 20hg every time. Much better than the stock DV. I heard it's much easier on the turbo when you put the Cold Air back into it as well. Who knows.
I should add that not only does the noise make you look/sound real cool, but it also aids in understanding what is mechanically going on under the hood. I find it useful.
^ I'm going to go out on a limb and say thats probably 100% incorrect . Cats are not cheap, unless you get them used. Also running a BOV will give you a cel and cause your maf to freak out. Also, you would need to plug the hole in your tip. Also, depending on year, by manually tuning it, you run a high risk of bombing your turbo and engine. Don't mean to blow up your spot or anything, just sayin. Also I'm in denver as well :thumbup:
yeahhh my bad.. i keep forgetting bout these cars computers..
im used to working on simpler supras 7m's and 2j's :wrench:
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