PDA

View Full Version : Yet ANOTHER BOV thread



sixfiveoh
08-27-2007, 11:08 AM
I was under the impression that our cars, like the S4s, ran metered air thru the stock bypass valves, making it bad to shoot any of that air back into the atmosphere with a BOV, like every single BOV thread has concluded. But 1997gtx states in this thread that a BOV will be fine on an A4. Any truth to this? I mean, I'm sure this couldn't have been overlooked, but what gives?


Does the A4 have the same motor design as far as the MAF being located before the BPV, making all of this info applicable to the 1.8T motor as well?


No, it's different. Most 1.8T's that I know of have no problems running a straight BOV.
--Adam


http://audizine.com/forum/showthread.php?p=1857281&posted=1#post1857281

AudiRacerS4
08-27-2007, 11:12 AM
if your car has a MAP sensor then you will have no problem running a BOV

sixfiveoh
08-27-2007, 11:14 AM
Do A4s have MAP sensors? Or did they vary from motor types? Do the AWMs have them?

AudiRacerS4
08-27-2007, 11:14 AM
your car is a 2001 so you have a MAP sensor it is located on your SMIC

sixfiveoh
08-27-2007, 11:19 AM
your car is a 2001 so you have a MAP sensor it is located on your SMIC

Wow, if it was that simple, how could all of these threads shunning BOVs have gone on this long? I'm assuming a BOV will hold plenty of boost, so when I chip, I can just go with an HKS SSQ as an upgrade to the stock BPV?

AudiRacerS4
08-27-2007, 11:21 AM
well only cars made in 2000+ have MAP sensors cars before before 2000 only have a MAF and BOV's are not ment to run on MAF equipped cars unless the BOV is located before the MAF

Nebone
08-27-2007, 11:26 AM
Buy a BOV and be happy.

AudiRacerS4
08-27-2007, 11:28 AM
or if you dont want to risk running rich at all buy a 50/50 DV that is recirculated and atmospheric like I have

sixfiveoh
08-27-2007, 11:57 AM
That's another thing I was about to ask, the only down point of running a BOV would be running rich between shifts, right? What valve are you running? Could I simply get an HKS and recirculate it to the airbox and run just as well as an upgraded DV? How loud is your BOV since it's recirculated? I know I'll probably get over it, but I want the noise. How much does recirculating it quiet it?

AudiRacerS4
08-27-2007, 12:03 PM
Im running a forge split r valve and its a 50/50 and its really loud

t1demont1
08-27-2007, 12:06 PM
will the 50/50 valves run fine on cars without the map sensor... aka pre 2000?

AudiRacerS4
08-27-2007, 12:19 PM
yes

sixfiveoh
08-27-2007, 12:38 PM
So in theory, I could just run a straight BOV on my car, and would have normal performance except for running rich for that split second when venting, correct? But the right thing to do would run something like the Split R. Why all the nay saying about BOVs in the past?

AudiA4_20T
08-27-2007, 12:41 PM
Why do you like the HKS? It sounds like ass... if your going to do it right get the GFB Stealth F/X or recirculate a Greddy Type S

Jereme
08-27-2007, 12:45 PM
dude,if you really want one then just get it. It's not good for the car, but when I first got my car i had one and its really not as bad as everyone makes it seem....

but soon enough your going to realize that its annoying as hell, and it just makes a slow car SEEM fast.

I'm not trying to shit on you or your car either, it just seems like you really want one and your looking for some sort of justification as to why you should get one even though you know you shouldn't. Like AudiRacerS4 said the 50/50 ones are and option but If it was me, I would just spend the money on a real nice DV...

TMorris
08-27-2007, 12:52 PM
I don't understand why there is always a thread on BOV. Everyone knows and every thread comes to the same conclusion. Yes you can run one but WHY!?

sixfiveoh
08-27-2007, 12:53 PM
Why do you like the HKS? It sounds like ass... if your going to do it right get the GFB Stealth F/X or recirculate a Greddy Type S

Idk, I'm partial to the sound. My buddy has one on his Supra, and I think it sounds decent. Maybe a bit extreme for a luxury car though...


dude,if you really want one then just get it. It's not good for the car, but when I first got my car i had one and its really not as bad as everyone makes it seem....

but soon enough your going to realize that its annoying as hell, and it just makes a slow car SEEM fast.

I'm not trying to shit on you or your car either, it just seems like you really want one and your looking for some sort of justification as to why you should get one even though you know you shouldn't. Like AudiRacerS4 said the 50/50 ones are and option but If it was me, I would just spend the money on a real nice DV...

The thing I'm trying to figure out is why it's bad for the car. That's what I can't understand. Is it the running rich between shifts? If I can see that it really is bad for the car, no doubt, I wouldn't let it touch the car.

I totally know where you're coming from on the slow car/fast sound thing. It's understandable, which is why I doubt I'd go for something really extreme like the HKS, I was just using it as an example. The Forge Split R sounded pretty good in some clips I saw, but it sounded like a loud DV, which I know EvoMS makes a pretty loud one.

I know, I'm a ricer, but I like my car to sound "intimidating" (even though it's a boat [:D])


I don't understand why there is always a thread on BOV. Everyone knows and every thread comes to the same conclusion. Yes you can run one but WHY!?

I guess the question I'm asking it why not? Why are DVs so much more recommended than a recirculated or straight BOV? Idk, this probably sounds like a broke record [:p]

Jereme
08-27-2007, 01:41 PM
I honestly don't know the real answer....

But when i had my BOV I didn't really have any problems. The only thing was the car would stutter when I was at low boost...say anywhere below 8psi.

Eventually I figured out that my BOV had an 8psi spring in it and It wouldnt blow off unless I went above that 8 psi....thus causing compressor surge everytime It didn't blow off...

btw, heres the vid I used to watch b4 i got my car. I wanted it sound exactly the same so i bought magnaflow exhaust and a forge 004 BOV just like the car in the vid.

http://videos.streetfire.net/Player.aspx?fileid=2C3CEC0F-530D-4BB0-B8FF-56F6FD3BE5CE&kw=29&p=1

sixfiveoh
08-27-2007, 01:43 PM
Holy damn, that's nice. But that's a BOV as well, right? No recirculating? So what would be the difference between this and any other BOV on the market?

Jereme
08-27-2007, 01:48 PM
yeah its just a BOV heres the link for it. I actually scored mine off ebay with one of the billet plugs for like 70$...

http://www.ecodetuning.com/shop/cart.php?m=product_detail&p=436

Poopie
08-27-2007, 01:56 PM
it all comes down to a personal preference. I personally they are annoying.

Jereme
08-27-2007, 02:00 PM
yeah mine got really annoying after a little while

ActiveMonkey
08-27-2007, 02:09 PM
I like my recirculated Greddy Type S with RS Springs. Holds boost no problem and doesn't sound too bad

nomoore
08-27-2007, 03:19 PM
The thing I'm trying to figure out is why it's bad for the car. That's what I can't understand. Is it the running rich between shifts? If I can see that it really is bad for the car, no doubt, I wouldn't let it touch the car.


Yes, the reason it's bad for the car is because it runs rich when shifting and generally when you let off the gas. This causes extra soot that can eventually clog stuff up on the exhaust side of the engine like your cat or your O2 sensors.

What cars will run rich? Definitely all cars without a MAP sensor which means, for our A4s, all non-drive-by-wire cars.

The drive-by-wire cars have a MAP sensor but they also have a MAF sensor so I don't know which of these it would primarily base the fuel map on. I'm not sure if these cars would run rich or not.

On a car with no MAP sensor the fuel map is based on a Mass-Air-Flow (MAF) sensor that measures how much air is going into the system. On our cars (as with most cars) the MAF sensor is located right at the airbox. The air goes through the MAF sensor before it goes through the turbo. The BOV/diverter valve is located after the turbo to let off the pressure when the throttle plate closes so it doesn't back up into the turbo and ruin it. The BOV vents the air to the outside so the air that has already been measured is lost and the fuel map is then too rich. The diverter valve recirculates the air back to the turbo inlet pipe which is after the MAF sensor but before the turbo. This equalizes the pressure on the 2 sides of the turbo but keeps the air in the system so the fuel map is not wrong.

98a4
08-27-2007, 03:39 PM
Oh MY GOD.

AUDIRACERS4 is an idiot.

Open your god damn hood and look at your maf. Saying 2000+ dont have MAF's is one of the most blantant incorrect statements on theses forums. MAP's by no means replace mafs.
Mass Air Flow sensor
Manifold absolout pressue sensor

Yeah reah close, I guess M + A = F or P its all the same...

"Equalizes the air on both sides of the turbo?" Apparently you need a re-fresher on turbos.

Now think logically here, when you shit, there is vaccume, not boost so the map sensor reads a vaccum. Doesn't mean a damn thing. Air comming in is metered already, proper fuel quanties are dumped based on that ammount of air. Releasing the air will cause the same ammont of fuel to be dumped, MAP or not.

With that said. I run a GFB hybrid, and its fine when tuned right, I've run SSQV and the car was known to stall going from boost to idol under no load engine decel.
Just because one person says it works you feel the need to ask AGAIN when literally over 500 times each thread has come to the conclusion that they are not a good idea.

You run rich between shifts
You have the possibility of stalling if its not adjusted right
It wont kill your car
DV;s are better
You will lag regaining boost between shifts

/End

speedydragon
08-27-2007, 04:37 PM
I like the high pitched bovs more than the ones that just goes sshhhhhh like the one in that vid from the previous post ^^

SoFresh
08-27-2007, 06:00 PM
When I ran my A4, I used the following on 16psi:

-Greddy Type S BOV
-Turbo XS RFL BOV
-HKS SS BOV

The Greddy Type S was a deep ppppshhh, the RFL sucked and then the HKS SS BOV was the loudest and was a quick high pitched sound.

In the end, the car idled rough with the BOV, so I ended up just running the 710n DV, made the car actually run at 17psi, and idled smooth, better performance with the DV over the BOV.

sixfiveoh
08-27-2007, 07:13 PM
So the Forge 004 is just a straight BOV and will cause the same problems as any other BOV on the market?

AudiRacerS4
08-27-2007, 09:40 PM
Oh MY GOD.

AUDIRACERS4 is an idiot.

Open your god damn hood and look at your maf. Saying 2000+ dont have MAF's is one of the most blantant incorrect statements on theses forums. MAP's by no means replace mafs.
Mass Air Flow sensor
Manifold absolout pressue sensor

Yeah reah close, I guess M + A = F or P its all the same...

"Equalizes the air on both sides of the turbo?" Apparently you need a re-fresher on turbos.

Now think logically here, when you shit, there is vaccume, not boost so the map sensor reads a vaccum. Doesn't mean a damn thing. Air comming in is metered already, proper fuel quanties are dumped based on that ammount of air. Releasing the air will cause the same ammont of fuel to be dumped, MAP or not.

With that said. I run a GFB hybrid, and its fine when tuned right, I've run SSQV and the car was known to stall going from boost to idol under no load engine decel.
Just because one person says it works you feel the need to ask AGAIN when literally over 500 times each thread has come to the conclusion that they are not a good idea.

You run rich between shifts
You have the possibility of stalling if its not adjusted right
It wont kill your car
DV;s are better
You will lag regaining boost between shifts

/End

I never said NDBW cars dont have a MAF i said ony the 2000+ cars have both a MAP and MAF sensor

AudiRacerS4
08-27-2007, 09:41 PM
Oh MY GOD.

AUDIRACERS4 is an idiot.

Open your god damn hood and look at your maf. Saying 2000+ dont have MAF's is one of the most blantant incorrect statements on theses forums. MAP's by no means replace mafs.
Mass Air Flow sensor
Manifold absolout pressue sensor

Yeah reah close, I guess M + A = F or P its all the same...

"Equalizes the air on both sides of the turbo?" Apparently you need a re-fresher on turbos.

Now think logically here, when you shit, there is vaccume, not boost so the map sensor reads a vaccum. Doesn't mean a damn thing. Air comming in is metered already, proper fuel quanties are dumped based on that ammount of air. Releasing the air will cause the same ammont of fuel to be dumped, MAP or not.

With that said. I run a GFB hybrid, and its fine when tuned right, I've run SSQV and the car was known to stall going from boost to idol under no load engine decel.
Just because one person says it works you feel the need to ask AGAIN when literally over 500 times each thread has come to the conclusion that they are not a good idea.

You run rich between shifts
You have the possibility of stalling if its not adjusted right
It wont kill your car
DV;s are better
You will lag regaining boost between shifts

/End

Also the MAP sensors on DBW cars has everything to do with fuel maps if it cant get a good reading from the MAF it will rely on the fuel trims from the MAP sensor this is the reason 2000+ plus cars can run with the MAF unplugged and and still have drivabilty unlike the NDBW

AudiRacerS4
08-27-2007, 09:50 PM
and if you have a BOV that is dual piston (ie does not leak in unmetered air under vacuum), your fuel trims will not be affected.

dualaudi
08-27-2007, 10:54 PM
So the Forge 004 is just a straight BOV and will cause the same problems as any other BOV on the market?

get the 004.. it's nice... i have only had the shifting rich issue everyone says is bad. I am not DBW, so i can't tell you that you will not stall - sounds like a jacked up ride to me.

My car has never stalled while shifting in any psi range. get one and be happy like everyone that's not haters of the BOV.

1.8 Tcat415
08-28-2007, 12:41 AM
hey SIXFIVEOH check out this group buy http://audizine.com/forum/showthread.php?t=150411 scroll down to post #4

this company says they DO NOT recommend BOV on audi's

Russell2686
08-28-2007, 01:39 AM
hey SIXFIVEOH check out this group buy http://audizine.com/forum/showthread.php?t=150411 scroll down to post #4

this company says they DO NOT recommend BOV on audi's

Come on man don't ruin his fun. He's looking for everyone to tell him why he SHOULD get one. If he wanted to hear all the bad stuff he would listen to the other million threads that are on here. [drive] pssshhh [drive] pssshh[drive]psssshh[race]

98a4
08-28-2007, 02:36 AM
Sorry miss read it.

Reguardless, above 4500rpm stock maf's cant give a good reading.

No reason to get technical, i laid it out already.

You can run it and it wont kill your car, but you'll trade that sound for some performance

nomoore
08-28-2007, 07:12 AM
"Equalizes the air on both sides of the turbo?" Apparently you need a re-fresher on turbos.
/End

Ummm.... no! What I said is correct.

When you let off the accelerator the throttle plate closes. The turbo is still spinning though because it is already spooled up. The turbo is still producing pressure for a few moments. Because the throttle plate is closed this pressure cannot go into the engine. The pressure has to go somewhere. Without a BOV or DV the pressure will go back through the turbo in the opposite direction and the backpressure can damage the turbo. If the pressure on the intake side of the turbo was the same as on the charge pressure side then the air would not be backing up into the turbo to do damage. So that's what a BOV or DV valve does. They let off pressure from the higher pressure side of the turbo so it equalizes to the intake side and doesn't back up into the turbo and abruptly stop the compressor. The only difference in the way they work is that the BOV vents straight to outside air and the diverter valve recirculates the air to the turbo inlet pipe. In reality the air never actually completely equalizes but it equalizes enough so that the difference in pressure is no longer damaging.

Pat@Forge
08-28-2007, 08:27 AM
We back our products with a 100% satisfaction guarantee. If you are so curious about the 004 you can give one a try with no risk, we will refund you if you aren't happy with how it performs.

AudiRacerS4
08-28-2007, 08:48 AM
like i said dual piston BOV's do not affect your fuel trims and the forge 004 is a dual piston BOV so you can run it and like pat mentioned you can try it risk free and see if you like it

dualaudi
08-28-2007, 09:10 AM
hey SIXFIVEOH check out this group buy http://audizine.com/forum/showthread.php?t=150411 scroll down to post #4

this company says they DO NOT recommend BOV on audi's

"We do not recommend running blow off valves on any Audi application."

Of course not.... but we'll sell them by the millions if you put in an order... You'll also see on a few products out there... "For off road use only" but 95% of those products are "on road only vehicles"

Get an 004 and enjoy...

Jereme
08-28-2007, 10:24 AM
the 004 worked really well, I just got sick of it..