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View Full Version : what's so bad about BOVs????? (a4-b5)



moreno_8903
10-15-2011, 12:38 PM
Hi, I was thinking on getting a bov but everybody says that it messes up the car. Can somebody explain to me why I shouldn't get one????

AudiNFS
10-15-2011, 12:46 PM
Search. It's been covered a lot. But to give you the short answer, our cars have Mass Air Flow sensors (MAF) and having a BOV causes the car to run rich, which is bad.

seanj130
10-15-2011, 12:48 PM
Hi, I was thinking on getting a bov but everybody says that it messes up the car. Can somebody explain to me why I shouldn't get one????

Ok. You don't care about power if you are running one, you want the sound.

Just run it and you will be happy. It will only affect performance by running rich.

moreno_8903
10-15-2011, 12:53 PM
So I need to get a DV valve. Another question does the DV valve sounds like the bov or not , cuz I really like that sound. And sorry about the stupid questions but this is my first turbo car

murdered APR a4
10-15-2011, 12:57 PM
just get a forge splitter valve its a 50/50 DV/BOV you can either have it fully DV or BOV or in the middle, has the sound and all but actually doesn't make the car run shitty

AudiNFS
10-15-2011, 12:59 PM
Another option I got pointed to at one point was the GFB BOV. It's a little pricey, but it's just like the Forge Splitter except it's a BOV and closes at idle and there's no clicking to adjust spring rate.

OP: You can have your DV and turbo spool louder with a cone filter as well, but just make sure you run a heatshield or else you will be sucking in all the hot air from the turbo. I will also offer you more advice, just incase. With these cars, maitenance is a must before any upgrades, just like all other cars. Also, do not take any short cuts with any sort of mods, or it will come back to bite you at some point.

If you don't have a boost gauge, make that your first mod. Stay out of boost until the car is up to operating temps., and do no just run the car hard and turn it right off. I always let my car cool down for about 20 seconds for normal drives (unless car wasn't even warmed up, I just turned it off) and after longer or harder drives, I let it cool down for about a minute. Had the car for a year without any problems.

If you have any questions just send me a PM and I will try to help.

TConklin821
10-15-2011, 01:11 PM
I promise, one question mark will get the point across.

sgt_g
10-15-2011, 01:26 PM
my car died at idle with a synapse bov and there antistal kit which has been proven to work on other cars for some reason my 01 it didn't like it. but using it as a dv it works great and is pretty darn loud with in intake and heat sheild.

moreno_8903
10-15-2011, 03:19 PM
Another option I got pointed to at one point was the GFB BOV. It's a little pricey, but it's just like the Forge Splitter except it's a BOV and closes at idle and there's no clicking to adjust spring rate.

OP: You can have your DV and turbo spool louder with a cone filter as well, but just make sure you run a heatshield or else you will be sucking in all the hot air from the turbo. I will also offer you more advice, just incase. With these cars, maitenance is a must before any upgrades, just like all other cars. Also, do not take any short cuts with any sort of mods, or it will come back to bite you at some point.

If you don't have a boost gauge, make that your first mod. Stay out of boost until the car is up to operating temps., and do no just run the car hard and turn it right off. I always let my car cool down for about 20 seconds for normal drives (unless car wasn't even warmed up, I just turned it off) and after longer or harder drives, I let it cool down for about a minute. Had the car for a year without any problems.

If you have any questions just send me a PM and I will try to help.

Thanks bro , that was a lot of help , ill definitely pm you if have another question.

1sikk04
10-15-2011, 04:30 PM
I have a forge splitter valve and it ain't 50 50 its 70 to intake and 30 atmosphere but its loud no problem with it and with a cone filter u get loud turbo spool and louder blow off ull be happy with it for sure.. a regular bov won't always make u run rich but could run lean which is worse cuz it won't see the extra air from the dv but it will expect it so it sees less air so it dumps less fuel get a splitter or 007 dv and u won't have problems I vote splitter if u want the louder pshht

M-Hood
10-17-2011, 05:34 AM
I have a forge splitter valve and it ain't 50 50 its 70 to intake and 30 atmosphere but its loud no problem with it and with a cone filter u get loud turbo spool and louder blow off ull be happy with it for sure.. a regular bov won't always make u run rich but could run lean which is worse cuz it won't see the extra air from the dv but it will expect it so it sees less air so it dumps less fuel get a splitter or 007 dv and u won't have problems I vote splitter if u want the louder pshht

Not sure why he thought the Forge splitter was 50/50, just 1 look at the instruction video shows that there are 2 different size holes on the side of the body. The GFB Hybrid is 50/50 and the GFB Stealth is completely adjustable, both of those were out long before Forge came out with the splitter.


BOV can cause the AFR to go slightly rich for a split second right after the BOV has released the pressure, after that point the BOV closes and the AFR goes back to normal. Since the IC pipes is always under boost pressure it is not possible for the BOV to cause the car to run lean.

As for your theory of the BOV causing the car to run lean because the ECU expects that air, that would be true if our cars did not have a MAF.

1sikk04
10-17-2011, 05:40 AM
Ah makes sense I feel dumb thanks for the knowledge

walky_talky20
10-17-2011, 06:06 AM
Forge splitter can definitely make the car run lean, especially at light throttle on a Drive-By-Wire car. The N249 will command the valve to open (partly to atmosphere) causing an intake leak out of boost = lean. Thus, splitter + n249 can wreak havoc on the fuel trims by causing both rich and lean situations at different times. Bypassing the N249 fixes most of that.

Dan[FN]6262
10-17-2011, 06:48 AM
if you want to run a BOV, run a Forge 004. It is designed to work with MAF cars, as it is a dual piston design and stays closed at idle and part throttle.

this thread is retarded

M-Hood
10-17-2011, 07:28 AM
Forge splitter can definitely make the car run lean, especially at light throttle on a Drive-By-Wire car. The N249 will command the valve to open (partly to atmosphere) causing an intake leak out of boost = lean. Thus, splitter + n249 can wreak havoc on the fuel trims by causing both rich and lean situations at different times. Bypassing the N249 fixes most of that.

You do understand that the IC pipes are never under vacuum? This is because the turbo is always spinning which means there is always a constant flow of air. Only thing that is under vacuum is the IM. This is basic stuff. lol

walky_talky20
10-17-2011, 07:40 AM
The valve is venting the TIP as well, not just the charge pipe (when fully open). I'm just saying, the fuel trims were plenty positive on this car (and it ran crappy at light throttle) until the N249 was bypassed. That is all.

sweets4style
10-17-2011, 08:02 AM
This is not true. You can certainly create a vacuum in the intercooler pipes when venting a DV or BOV. This is incorrect information. Yes it is always spinning but you mistaken pressure in one side, a different pressure on the other side, and pressure AND volume leaving. Also why would you believe the intake manifold is under vacuum when that is connected to the IC pipes and yet you claim that is not under vacuum. Just trust me when I tell you it is under vacuum.



You do understand that the IC pipes are never under vacuum? This is because the turbo is always spinning which means there is always a constant flow of air. Only thing that is under vacuum is the IM. This is basic stuff. lol

M-Hood
10-17-2011, 08:03 AM
The valve is venting the TIP as well, not just the charge pipe (when fully open). I'm just saying, the fuel trims were plenty positive on this car (and it ran crappy at light throttle) until the N249 was bypassed. That is all.

It can if it allows the TIP to suck air in unmetered air. Which is why some of the hybrid valves offset the outlets on the valve, putting the BOV outlet higher then the return to the TIP. This is also why the splitter has a smaller hole for the BOV outlet.

ECS Tuning-Audi
10-17-2011, 08:32 AM
I run a 710n DV and a cone filter with a heat shield and the DV is definitely loud enough for my tastes. My car runs perfectly as well.

Jason

M-Hood
10-17-2011, 09:50 AM
This is not true. You can certainly create a vacuum in the intercooler pipes when venting a DV or BOV. This is incorrect information. Yes it is always spinning but you mistaken pressure in one side, a different pressure on the other side, and pressure AND volume leaving. Also why would you believe the intake manifold is under vacuum when that is connected to the IC pipes and yet you claim that is not under vacuum. Just trust me when I tell you it is under vacuum.

The IM is under vacuum because the TB has blocked off the opening from the charge pipe.


IF the charge pipe was under any type of vacuum your BPV vac line would be hooked up to the charge pipe not the IM. [o_o]

ZimbutheMonkey
10-17-2011, 03:59 PM
I'm running a bit of a hybrid setup on my 60-1 and it seems to be working OK. I kept the factory DV and put the BOV right by the compressor discharge. That said, I'm pushing more than twice the air that a chipped K03 or K04-015 moves, and there isn't a single factory piece in my charge piping other than the DV (well, it's a TT diverter valve, but you get the picture)

PS: I'm also an AEB so no N249 either

chodemaster
10-17-2011, 04:34 PM
http://i52.tinypic.com/2zzq49s.jpg

M-Hood
10-17-2011, 06:35 PM
I'm running a bit of a hybrid setup on my 60-1 and it seems to be working OK. I kept the factory DV and put the BOV right by the compressor discharge. That said, I'm pushing more than twice the air that a chipped K03 or K04-015 moves, and there isn't a single factory piece in my charge piping other than the DV (well, it's a TT diverter valve, but you get the picture)

PS: I'm also an AEB so no N249 either

Why didn't you put the BOV near the TB?

ZimbutheMonkey
10-17-2011, 08:03 PM
Because the DV was already plumbed in there and if possible I wanted to only use the DV just to keep the compressor spooled between shifts. So it basically had priority in terms of location. The BOV was installed primarily to prevent compressor surge, and locating the BOV right near the discharge port will give you the best venting for that purpose IMO. I basically thought of it like a dam. You want to place the gates right by the area you want to regulate, not 10 miles upstream. Maybe there are other schools of thought on the matter, but that was my thinking.

TJN0923
10-17-2011, 09:37 PM
http://i52.tinypic.com/2zzq49s.jpg
LMFAO.
OP, just get a forge splitter. it's plug n' play and you get the best of both worlds. BOV when you want it, and you can cap it off at any time to make it a full DV.

M-Hood
10-18-2011, 07:05 AM
Because the DV was already plumbed in there and if possible I wanted to only use the DV just to keep the compressor spooled between shifts. So it basically had priority in terms of location. The BOV was installed primarily to prevent compressor surge, and locating the BOV right near the discharge port will give you the best venting for that purpose IMO. I basically thought of it like a dam. You want to place the gates right by the area you want to regulate, not 10 miles upstream. Maybe there are other schools of thought on the matter, but that was my thinking.

Well placed anywhere will work since all your doing is reducing back pressure in the whole system and that back pressure starts at the TB when it closes. BOV put near the TB just acts like the TB but letting the air out instead of into the IM. What helps with putting it closer to the TB is that air is still traveling to that point and you end up with less dead zone area that has to be covered once the BOV closes and the TB opens.

Dan[FN]6262
10-18-2011, 07:14 AM
LMFAO.
OP, just get a forge splitter. it's plug n' play and you get the best of both worlds. BOV when you want it, and you can cap it off at any time to make it a full DV.

Forge Splitters suck.

M-Hood
10-18-2011, 08:18 AM
5857;6953454']Forge Splitters suck.

I liked both of the GFB dual outlet valves I used on my car back when I was running ECU tuning.

flynnr
10-18-2011, 08:24 AM
since this thread has already been answered, i have a quick question. I have a homebrew setup waiting to be installed to relocate my bov to the TB side - right now it is on the pipe connecting the IC to the turbo - so when i move it to the other side there will be about a 1" hole that needs to be capped. what is the best way to cap said hole? It will have a lot of pressure on it, so i dont want something that will be able to come loose. i was thinking maybe jb weld it shut, but idk if that will hold.

Seerlah
10-18-2011, 09:05 AM
What type of nipple/port is it? Best bet would be to eventually get that piping replaced. Or take it off, take it to a shop, have the port cut off, and a plate welded on it.

PhillyOne
10-18-2011, 10:25 AM
5857;6953454']Forge Splitters suck.

whys that? Was planning on getting one.


& OP there is a sh*tload of threads on this already. I'm a new owner and barely post on here because of the search box in the top right.

flynnr
10-18-2011, 11:07 AM
What type of nipple/port is it? Best bet would be to eventually get that piping replaced. Or take it off, take it to a shop, have the port cut off, and a plate welded on it.

this nipple

http://www.racetec-us.com/

TJN0923
10-18-2011, 11:09 AM
5857;6953454']Forge Splitters suck.
Maybe. But it's the simplest way to accomplish what he's going for.

Seerlah
10-18-2011, 11:12 AM
I am assuming you have some type of hose (silicone maybe) clamped onto that, then clamped onto your dv? Just take out your dv and place a Dorman Expansion Plug in place of it (clamp it down, of course). Then if you plan on sticking with that intercooler for a while, take it to a shop, have them cut off that extra piping for the dv/bov, and weld an aluminum plate over it. Or leave it with the expansion plug, for an easy resale. That's what I would do, anyways.

You running a BOV or DV?

M-Hood
10-18-2011, 12:02 PM
this nipple

http://www.racetec-us.com/

You just need something like this http://www.forgemotorsport.com/content.asp?inc=product&cat=0016&product=FMTB052K

flynnr
10-18-2011, 01:22 PM
I am assuming you have some type of hose (silicone maybe) clamped onto that, then clamped onto your dv? Just take out your dv and place a Dorman Expansion Plug in place of it (clamp it down, of course). Then if you plan on sticking with that intercooler for a while, take it to a shop, have them cut off that extra piping for the dv/bov, and weld an aluminum plate over it. Or leave it with the expansion plug, for an easy resale. That's what I would do, anyways.

You running a BOV or DV?

yeah im using a chunk of hose, clamped over that nipple, and onto the bov. I am running a DV, but diverting it straight to atmosphere, so in essence its just a bov.

flynnr
10-18-2011, 01:22 PM
and no, im not sticking with the shitty overpriced racetec fmic

Seerlah
10-18-2011, 01:32 PM
Advanced Auto Parts sell the Dorman expansion plug for like $4 (Dorman 1" expansion plug pn: 10027). Just replace the dv with that, and call it a day.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_x_22140129-P_x_x?cm_mmc=CSE-_-Google-_-VALUE3-_-VALUE4&ci_src=14110944&ci_sku=

flynnr
10-18-2011, 01:41 PM
thanks - should i put that plug directly in the aluminum piping? will it hold 25psi easily?

or should i leave the small chunk of rubber tubing on, and put this in the end of that, and hose clamp the plug in there for reinforcement??

Seerlah
10-18-2011, 01:48 PM
I am not sure how those plugs work, but they are supposed to be used for plugging ports. I have seen plugs that have the rubber expand, so that plug may work in the same fashion (looks like you can thread the nut down, and the rubber expands. that is just a conjecture by looking at it though). If so, try it out like that first. If the pressure is too much, then keep it on the rubber hose with a clamp.

M-Hood
10-18-2011, 07:19 PM
thanks - should i put that plug directly in the aluminum piping? will it hold 25psi easily?

or should i leave the small chunk of rubber tubing on, and put this in the end of that, and hose clamp the plug in there for reinforcement??

You need to use a very short piece of rubber hose and basically but the the plug and the pipe together.