This is the big BOV thread. If you didn't find this thread, you didn't search.
This thread is where all BOV question threads get merged into.
The quote below in this first post is from our BOV info sticky and contains links to some very explanatory BOV information. Please take the time to explore the links before you ask repeated questions.
A stock WRX/STi comes with a BPV (Bypass valve) which is a vacuum-actuated valve designed to release pressure in the intake system when the throttle is lifted or closed. This air pressure is re-circulated back into the non-pressurized end of the intake before the turbo.
An after market blowoff valve (VTA) does basically the same thing BUT unlike the stock unit it releases air to the atmosphere (giving you the loud sound). Some people see an after market BOV on a stock WRX as being in poor taste (probably due to the fact that it is basically a noise maker that really as no other benefit), while others simply find the sound very attractive.
Proponent opinions notwithstanding, there is a small mechanical downside to having an after market BOV (VTA) on a stock WRX. The problem comes when releasing air to the atmosphere that has already been metered by the mass airflow sensor. When the BOV releases (blows off), the ECU will be injecting the wrong amount of fuel into the cylinders. The engine temporarily runs too rich (meaning too much fuel is injected into the cylinders). This temporary rich condition isn’t typically THAT harmful, but it may cause bucking or hesitation on lift-throttle as well as some other concerns outlined in the links below.
Pros: Sounds awesome has two modes 50/50, 100%
Cons: hmmm.... some people have had problems running it at 100%
Thats about it, I have not run it at 100% yet so I don't know if it will affect my car yet or not, I am gonna wait until I can tweak my air fuel mixture so I will not have any problems.
I also had a GFB BOV and got rid of it. These BOV's are known to have idle problems. The piston in the main body of the BOV sticks open at idle causing the car to get a very low idle tone and feel like its almost about to die. You can remedy this by taking the BOV apart, and lubricating the piston with Slick 50 or Duralube, so it stops it from sticking.
Including a scan of the info page that came with the GFB. I believe they have updated the valve since the early models. I had heard of people having some issues early on, but not with any of the brand new ones... so far so good with mine... love it.
very nice a crisp sound...
if u set it at 50/50 u can kind of anticipate the sound if u go over 4000rpms.... i also heard running at 100% will cause some problems, such as your car running to lean, etc.
but this is the case in running any BOV 100%
Yeah, I tried running the HKS SSQV 100% valve and it made the car run horrible. I have heard of alot of people running the Forge 100% ATM and not having any problems though. I personally don't understand this because the return tube is still plugged up, but thats cool... I was going to buy a Forge, but there was a thread on NASIOC where people were trying and trying to get the guys from Forge to respond as to why their valve wont cause problems and they kept side-stepping the question and just saying "valve is still on sale for christmas! It wont cause any problems!" At that point, I gave up on them. I figured if they couldnt give an explanation to backup their claims, I wasnt giving them my $. I spent almost 2 months reading posts and going back and forth on what valve to buy. I was between the GFB and HKS... I tried the HKS first and my car ran horrible with it... decreased power and loss throttle response between gears. It felt like I was towing a boat when I hit 2nd gear (but it sounded sweet). I sold the HKS after only 1 day of use and bought the GFB instead. I am very satisfied, and also it helps my paranoia of running a 100% ATM valve. lol
I had the HKS on my car for 1 day. I trimmed a small piece of the extra long hose I needed (used it to replace the elbow shaped stock tube if I remember). I just connected that tube to the BOV and also to my T connector for the boost gauge and that was it I think. Of course, I plugged up my return tube with the metal plug and stuck the hose clamp back on it. As I've said many times (and I'm not going to rehash it yet again, lol)... my car ran terrible with the thing. It sounded cool, but d@mn... I took it off and sold it ASAP. Went with the GFB in hybrid mode instead...
PS - The HKS came with a weird plastic connector thingy. I tried it with and without that thing and it didn't change anything in terms of the way the car ran. I had a local guy help me with the install initially who had experience with BOVs, so I'm fairly certain it was hooked up right.
coool.... yeah i chopped off some of the tube and plugged it into the lil connector thing they gave and then to the stock tube then put it into the T connector.. mabye i should just try to go strait on from the hks tube to the T connector... hmm... so it fits on there well then?
I had the HKS on my car for 1 day. I trimmed a small piece of the extra long hose I needed (used it to replace the elbow shaped stock tube if I remember). I just connected that tube to the BOV and also to my T connector for the boost gauge and that was it I think. Of course, I plugged up my return tube with the metal plug and stuck the hose clamp back on it. As I've said many times (and I'm not going to rehash it yet again, lol)... my car ran terrible with the thing. It sounded cool, but d@mn... I took it off and sold it ASAP. Went with the GFB in hybrid mode instead...
PS - The HKS came with a weird plastic connector thingy. I tried it with and without that thing and it didn't change anything in terms of the way the car ran. I had a local guy help me with the install initially who had experience with BOVs, so I'm fairly certain it was hooked up right.
I lost power, basically. The turbo wasn't staying spooled between shifts at all and when I hit 2nd gear it basically felt like I was towing something heavy. I have done alot of "research" on BOVs before I purchased and it really just seems some cars run fine with the 100% and others do not. I haven't been able to determine why exactly this is. I sold the HKS to a guy on NASIOC and he PM'd me a few days later and said his car ran fine with the thing with no adjustments, etc to how it showed up at his house which was directly off my car. It sounded great, but the difference was blatantly noticable and I wasnt will to sacrifice power. Conversely, the car actually seems to run better with the GFB. And no, I didnt go straight from the HKS to the GFB. I went stock > HKS > stock > GFB
Anyhow, thats just my experience with the HKS. If your car runs perfectly with the thing, then thats cool...
I had a TXS HRFL and my car ran a little choppy at Idle. Installed the HKS SSQV and the Idle was just like new. The SSQV is an awesome BOV and I am on my 3rd for the rex. Think I found a winner.
The HKS sounded awesome... believe me, I didn't want to get rid of it. It seems that particular valve maybe reacts better on modded cars. Mine is pretty much stock as of now until I can manage to put 5000 miles on it and bring it over to Cobb. I bought it in August and I'm only 1/2 way there. I was getting ansy and wanted to buy something...
eheh, the V2 lip is awesome. I slapped that on within a couple weeks of the STi wing and projectors. The V2 totally makes the car looks-wise from the front IMO.
I just installed this bov w/ mounting hardware from enthuzacar. Everything went well, but the BOV sounds very quiet. I noticed there are two lines that need to go somewhere. The main line, I have tapped into my vacuum where my old bov went. Now there is a smaller line where I have no idea where it goes. Should I just plug it up, leave it, etc?
Currently, I have the other line not going anywhere.
It's a 100% atmo., but has 2 nipples instead of one like most BOV's do. It doesn't seem to be blowing off. I don't think the unit is defective because it works sometimes, but is very faint. If I had a leak, where would I check. It still boosts to 14psi and doesn't taper or spike. It basically exhibits the same behavior as my stock BPV in this regard.
It sounds weird because I'll get on it and when you're normally supposed to hear the BOV when you release the throttle, it flutters and there is a very faint whistle. I can hear the BOV better @ WOT though. Dunno what's going on. Very weird.
Did you plug the return hose that was connected to the stock BOV? If you did, then I don't know what to tell you bud. Try emailing the place you bought it from. I'm sure they can offer you some advice. Good luck
Yeah, I don't know what's going on either. And yes, the hose is plugged. I guess I'll check for leaks. I dunno if this has anything to do with it, but I just installed a uppipe and header last week before the bov. It's leaking a little because it has crappy gaskets, but I'm getting new ones next week. Can any of this be related?
Well, if the uppipe is leaking, you won't be making proper amounts of boost. That could be it. If you're not making boost, you won't be blowing any off...that didn't sound right, but you get the idea Do you have a gauge to see how much boost you're making?
At first I was going for the TXS RFL b/c it looks SICK and i heard it actually is really fu<#ing loud! But there is so much talk about the Forge. I know the RFL is about $180 and that it's very loud, and I know that the Forge is very reliable. My question is, how much is the Forge, and which one is "better"?
TurboXS looks AWSOME & I heard it's very loud. Forge bov is very reliable, but how much does the Forge cost and where can I get it? Please help, I need a BOV asap.
I'd hate to tell you this, but I think I see a whole lot of A$$ rippin coming your way in the ways of "why don't you use the search button?" There are tons of info within the forum.
Well just put my StealthFX GFB hydrid in. A snap to install even for me. Love the sound. Alot better throttle response and the turbo doesnt drop as much between shifts.
And being adjustable on venting mixture and BOV volume it's so perfect. When I want to just cruise quietly I can turn it all the way down. And adjust it perfectly for no stalling backfire or any other problems.
OR run it to full atm vent and sound all the way up for scaring old people and terrorizing honda and mustang drivers.
You can hear this thing for 2 blocks when it's all the way up..
It was 240 but I think it was worth the extra since I think the sound would get annoying all the time at the same volume. The option to turn it down is a must have IMO.