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"The BIG BOV thread" (Where all bov question threads get merged)

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#1 · (Edited by Moderator)
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.

Thanks!


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.


Links for BOV info:

Sinister's BOV FAQ

Wikipedia

Unabomber on Nasioc

Davenow on Nasioc





 
#6,306 ·
TOOFAST88 said:
or think that you're car needs something fixed:rolleyes: , I've gotten both reactions...
hahah when I had my Integra we had a sweet thread over on team-integra about some of the stupid things people have said or asked about our cars, it was one of the best threads ever it was hallarious
 
#6,307 ·
Sorry, I just had to point out that little thing. It's kind of like a doctor not knowing which side of the body the heart is on, or a teacher not knowing how to spell school. Just somewhat odd if that's going to be your chosen trade, and somewhat funny if you didn't just go into it.

http://features.evolutionm.net/article/machvcorner/29 Supporting
http://forums.nasioc.com/forums/showthread.php?t=468038 Supporting

Again we're back to Benefits = 0 on a mildly modded car.
Would you care to list the negatives again that you listed above and count those up?

I'm grasping at anything because you're not reading anything. Go argue with Dan @ MachV after this if you'd like. He actually does this for a living and I'm sure he's spent more time under the hoods of cars than "parroting" what he found in his text books online.

I'm done with this, I've proven my point and provided documents from professionals proving that ATM BOV's are nothing but a stupid noisemakers and have more negatives than positives.

Again if the original poster wants an unbiased source(I admitttedly hate show off valves) he can search on his own and draw his own conclusion. I know what he'll find.

Also, If he wants to save money and not have any of the downsides of a BOV he can sell it and get a kazoo.You don't even have to hit the gas pedal for it to make noise. I'm sure they even sell JDM ones for the uber import fanatics.

Thank god for the Ignore feature & Best of luck with shcooal.


04wrx4keeps said:
Wow, after all of that you come back by telling me I cant spell, yea spelling has never been one of my strong points, your point with that is? Yea thats really pertinent to your argument, all my information must be wrong because I cant spell right?:confused1 ... I'm going to school to be a Tech not an English major, I'm sorry if my spelling isnt up to your high standerds, its a hell of alot better than alot what I see on these boards.

The information came from my textbook, that doesnt mean that I'm sitting here copying it verbatim out of the book, (actually the books were in my car) if I had to copy it out of the textbook then I probably wouldnt have a 98% GPA in class right now.

And where did you ever get that I was a first year student from? you dont know me and have no idea where I've been to school or what I have done for a living.

I guess when you dont know what your talking about the only thing you have left to argue with is spelling, I'm glad you know so much about cars and didn't even know what cold start enrichment was :confused1 must be your pride is just to inflated to admit you might be wrong so you have to grab for whatever you can reach, even I can admit that I cant spell.

And so far I have never seen a single professional state that an atmospheric BOV will damage anything, I've heard pleanty of them state that it wont improve performance on a close to stock vehicle (which is true), but I have yet to see any acounts of one actually damaging anything (the rumour that your perpetuating).
 
#6,308 ·
scooby888 said:
I know someone who put the Perrin short ram intake on and his sound rivals my HKS SSQV BOV...it was the weirdest thing!

I personally hate the BOV sound & wish that I could find a quiet bov for my setup.

The only positive side to an intake is that you actually may need it down the road if you chose to mod your car beyond the limits of the stock airbox. .
 
#6,309 ·
#6,312 ·
I thought BOV's were needed when exceeding 22psi on an upgraded turbo or something like that? In fact I think my friend's Mitsubishi 3000GT VR4 blew out my stock BOV completely with whatever power it makes. Somewhat of a noob here on this though.

I still love the BOV sound...especially since I am now tuned for it...
 
#6,313 ·
scooby888 said:
I thought BOV's were needed when exceeding 22psi on an upgraded turbo or something like that? In fact I think my friend's Mitsubishi 3000GT VR4 blew out my stock BOV completely with whatever power it makes. Somewhat of a noob here on this though.

I still love the BOV sound...especially since I am now tuned for it...
Tuned for a bov? if you're running a MAF you're not, I don't know that speed density even allows you to be tuned for it. I know I still had some problems with stall & afterfires from running rich. .. but that could be me and could be caused by tons of ****.

I've read that around 19PSI is about the limit on the stock wrx bov. Most people with pump street tunes aren't going to be exceeding that.
 
#6,314 ·
the best way i can describe the sound is it sounds just like a tire that got a big nail in it and is losing air quickly. hissssssssssssssssss. i got under the car when it was running today and it is very noticeable around the downpipe, and is slightly quieter over the turbo. not sure if things are resonating inside the exhaust or it is indeed the point of origin.
i think i mentioned it before but my txs downpipe to racepipe flange has a small leak. i got a new gasket today and am going to try to put it on tomorrow. i doubt this is causing the sound because i have never heard an exhaust leak like that before, but either way it'll fix an exhaust leak that i had so thats a good thing either way.
i also got an uppipe-turbo gasket that i will put on when i have some more time. when i install that i'll be pulling the turbo out so i'll have a chance to redo all of the connections and hopefully fix whatever is wrong.
boooo to cars.
bryan

SD GR:
the coolant line? i disconnected the coolant line running to the turbo when i pulled it off, but i put it back on.
 
#6,315 ·
BrianH said:
Sorry, I just had to point out that little thing. It's kind of like a doctor not knowing which side of the body the heart is on, or a teacher not knowing how to spell school. Just somewhat odd if that's going to be your chosen trade, and somewhat funny if you didn't just go into it.

http://features.evolutionm.net/article/machvcorner/29 Supporting
http://forums.nasioc.com/forums/showthread.php?t=468038 Supporting

Again we're back to Benefits = 0 on a mildly modded car.
Would you care to list the negatives again that you listed above and count those up?

I'm grasping at anything because you're not reading anything. Go argue with Dan @ MachV after this if you'd like. He actually does this for a living and I'm sure he's spent more time under the hoods of cars than "parroting" what he found in his text books online.

I'm done with this, I've proven my point and provided documents from professionals proving that ATM BOV's are nothing but a stupid noisemakers and have more negatives than positives.

Again if the original poster wants an unbiased source(I admitttedly hate show off valves) he can search on his own and draw his own conclusion. I know what he'll find.

Also, If he wants to save money and not have any of the downsides of a BOV he can sell it and get a kazoo.You don't even have to hit the gas pedal for it to make noise. I'm sure they even sell JDM ones for the uber import fanatics.

Thank god for the Ignore feature & Best of luck with shcooal.
For one thing I dont know where you're getting this point that I somehow listed all sorts of negatives toward my own argument in my posts. I also never said that BOV's do anything positive other than make noise, its simply up to what someone likes. If you dont like BOV's THEN DONT PUT ONE ON YOUR CAR.

Both of the articles you quoted state that there have not been a significant number of problems with Aftermarket BOV's, and that the rich running condition isnt usually harmful, and only list catalytic converter problems IN SEVERE CASES. So yes, I suppose in severe cases you could see some damage. That holds true of just about any modification you do to your car though. In severe cases an aftermarket exhaust could cause problems, modifying your car at all could cause problems. I went almost 40k miles on mine with an upipe cat though, all types of driving conditions and a number of trips to the track and my cat was perfectly fine, as well as a number of people I know with WRX's who have had no problems with them at all, and with an RFL i guess that mine would probably be about the most severe model you could get right?

Obviously due to your absolutely unfaltering hatred of BOV's I can imagine you have never in your life actually installed on any of your own cars. I actually have personal experience with them as opposed to just sitting my fat ass in front of the computer all day doing searches like some people... as I stated above I have had one for over 50k miles and almost 3 years (much of that time with the stock cat and no problems or visible damage to it at all when it was removed), as well as many friends with turbocharged cars who run them too, and when adjusted properly none of us have run into any issues.

IF YOU DONT LIKE THEM THAN DONT FING BUY ONE, IM NOT TRYING TO SELL YOU ONE, BUT STOP TELLING US WERE ALL IDIOTS BECAUSE WE ACTUALLY LIKE THE SOUND.

And as far as the whole doctor not knowing which side of the heart thing, I hardly see how my ability to spell has anything to do with my mechanical aptitude whatsoever. I have been to many shops and never once have I or anyone else ever had to write a report out that was crucial to the matanance or reparis being done. I'm done with this argument . Its ignorant closed minded people who think they know everyting like you that are the reason I rarely post on these boards anymore, have fun spreading your doomsaying, I hope someday you actually find that stick in your ass so you can lighten up a little bit.
 
#6,316 ·
bump.

i put the new downpipe/racepipe gasket on and it didnt change the sound. looking for some new ideas here if anyone has any...

bryan
 
#6,317 ·
Well I guess you could call it tuning...had my car dyno tuned at KTR Performance in Ayer, MA with ECUTek. Ever since then, the afterfire has been at a minimum (some days it doesn't even "pop' at all).

I thought the aftermarket BOV problems were with the 02-03's. Had a BOV and ram air Greddy/HKS Intake for about 20,000 miles with no problems (only other mods at the time were UP, DP and SPT catback) and definitely no stalling on an '04. Just a lot of afterfire until the re-tune above.

I could be wrong and just have a freak car though. But yes, I do totally agree that people with pump street tunes aren't going to be exceeding 19psi.

I am still pretty much a noob and don't claim to be an expert on the subject though.
 
#6,318 ·
You might want to check the manifold to uppipe gasket to see if there is a leak. I know you probably didnt remove the uppipe during the turbo work, but when you put the turbo back on you could of forced the uppipe to an angle and caused the up-manifold seal to have been lost. The only reason I say to check this is because the same thing happend to me, and it was not the typical exhaust leak sound either, it had the same hissing noise. Other than that I think it is probably somewhere in your charging track.
 
#6,319 ·
thanks for the idea. i actually ported my manifold last week and noticed a small amt of carbon buildup on my manifold/uppipe gasket which would indicate a slight leak so it needs to be replace anyways. the sound didnt change after i put the manifold back on though so i never suspected it was a problem.
tomorrow i am hoping to replace both uppipe gaskets and also put new oil line banjo bolt washers on all 4 spots because im' getting a slow leak there.
hopefully just pulling the turbo and replacing the gaskets and such will cure my problems, knowingly or not.
bryan
 
#6,320 ·
A good option is to just pull the silencer. You'll hear the bpv with the windows down, but it doesn't intrude on daily driving comfort much.

I remember when I had a TurboXS Type-H. It was so cool for 3 days, then I wanted to wear earmuffs just to drive around town. I switched to a recirculating valve and it's like having a luxury car in comparison. Plus I don't stumble at idle any more...
 
#6,321 ·
can't we all just get along.
i question the commraderie between all of us Scooby lovers. we don't show love like other car cliques show to each other. this is funnier than them giving each other reach-arounds though.

damn ignorant people need to learn. STOP BEING STUPID AND GET AN EDUCATION ! ! ! i swear if these people spent half as much time learning as they do beatin it to Michael Jackson videos we would all be driving hydrogen power rockets . . . or just have lower gas prices.
 
#6,325 ·
Get ready to deal with the ****ing dual springs on that, I'd worry about it more if I didn't have antisurge ports. . . hopefully they do their jobs. If you do have surge issues you're liekly not going to be able to cure them with the adjuster screw, get ready to play grabass with the springs.

Looking at mine I can't imagine that it would bolt to the stock WRX or STI tmic without an adapter of some type.

Did you get the Recirc kit?
 
#6,326 ·
BrianH said:
Looking at mine I can't imagine that it would bolt to the stock WRX or STI tmic without an adapter of some type.
^ you are correct...the proper flange-style should look like this..but would mate to a Greddy Bov instead of a TXS...

 
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