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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





 
#7,671 · (Edited)
I vote that someone who does not have any idea what they are talking about stops posting "facts" Your awesome cobb stage 1 experience must have made you learn so much! Why don't you go get a wideband put on your car to see just how rich cobb makes you run...And why don't you also use it to see just how little a BOV does to your a/f...Everyone needs to stop being a bunch of pantywaists, and start learning before they post that a BOV will hurt your motor...
 
#7,672 ·
yeah cuz hes the only one who says that about bovs. yup, not one other person has ever said anything bad about BOVs...:screwy: :rolleyes:

yea cobb makes it rich, but at least it IMPROVES performance from stock. bov usually result in loss of power. a lot of people have bought them, ran em and felt a loss, and put them up for sale. id say looking at the % of people with wrxs running a bov to those without them, thats a good example. brains over being a "pantywaist". i agree on bannage.
 
#7,673 ·
I agree that you are a retard. How do you feel a loss between shifts? Ban someone because they use logic? How about you get the ban for being a bandwagon idiot. And "felt a loss" really isn't a valid way of determining performance. Maybe the engine temp was higher, maybe the humidity went up, maybe there just IS NO PERFORMANCE DIFFERENCE FOR BETWEEN SHIFT THROTTLE PLATE CLOSED AIR METERING!!! Why are WRX owners so against a harmless pshh noise?
 
#7,674 ·
vote for ban is saracstic way of saying youre just picking fights. why are we retards for telling someone who is asking a question about a part, that everyone agrees hurts the car, and telling them our opinion.

explanation and yet another thread about no bov.
http://www.clubwrx.net/forums/showthread.php?t=151920&highlight=bov
theres a million threads about this. one after another after another. the question u have to answer, is why would u WANT your car running rich?why? for the pshh sound? just do the silencer delete. its not the coolest thing in the world and certainly not worth hindering the power of your car and burning more gas. how about this. ill put a cobb ap on my car, and u put abov on yours, and well race. since well both be running rich but u have the sound youll win right? god, i dont know how many horses have to get beat for this point to come across without u calling people retards. its bad for the car, it hurts mpg, efficiency, power, and other problems people have had. so why do it? answer that question.
 
#7,675 ·
You made a lot of unfounded claims there...yet again no logs on wideband data to back it up. Just like every other BOV argument. I would say off throttle the amount of fuel being pumped into the cylinders is about...zero. So rich lean, who cares? How is that effecting gas milage? How is that making you lose power? How is it making you slower? BOV does not effect mixture when you are on the gas...when mixture actually matters. I am calling people names because there is a whole mis-informed culture in the wrx community that a bov will hurt you car. No it won't if anything a accessport super rich tune will hurt your car, but no one complains about that...
 
#7,676 ·
Plusses: More quickly fouled plugs, pointless noise, dirtier rear bumper, fireballs (OMGz Dawg!!), potential damage to the cats if you still have them.

But I guess it does allow you to announce to all the other 16 second cars that you've arrived as you pull into your 'spots' parking lot and proceed to make the woosh(zomg!!!) noise 30 times while finding a spot.

Get a kazoo or a ****ing air horn, they are cheaper and guaranteed not to cause you any problems. You'll look just as stupid. It's about the same as adding neons to your car, pointless and an attention getter. Goes great with NOS stickers!

As for wideband AFR data, it's a MAF based system. You're taking air out that it's expecting & compensating for with fuel. What do you think it's going to get leaner? It doesn't take a datalog to prove this, just knowledge on how a MAF based system works.
 
#7,678 ·
Oh so the throttle plate is closed so it doesn't matter that the airs not going into the motor. hmm the fuel still is, that would explain the rich condition seen by everyone.

thanks for supporting my argument, and common knowledge on how a maf based system works.

WOOSH !
 
#7,682 ·
Ok...throttle plate closed...the computer knows that your Throttle position is at 0...and no air is going into motor, no air no fuel. And a BOV makes you have less hp how? I would say with throttle plate closed you are making 0 hp anyways.

Throttle plate is closed air between the maf and the TP has already passed the metering, taking it out the motor is still going to compensate for that with fuel. Hence a rich condition.

I didn't say it made you have less HP. It just makes you someone that likes to sound fast.

woosh!
 
#7,690 ·
I never meant that the MAF metered it going backwards...I meant some air inevitably escapes. And you motor does not need any air or fuel to idle when the wheels are driving the engine forward. At 4k rpm throttle plate closed...there is far to little fuel and air being drawn to idle the motor.
 
#7,696 ·
No need for a BOV.. i was in the same position as u when i got my car and i got so many people telling me not to get one.

Instead i got an SPT Short Ram Intake, and got a great Wchsh from it. haha

If your not pleased with that little amound of noise that the intake gives you, do what i did and take out ur intake silencer which takes about 10 minutes, to find out how to do that, just search "intake silencer" on clubwrx.

Once i did that, i found out there was no need for a bov because i had the perfect WHCHSHHHHHH i wanted for my car:)

hope i was a help to u
 
#7,699 ·
i ran stg 2.5 with a worx bov set at 100 atmosphere for a while, then switched to 50/50 when it ran crappy. when at 50/50 it ran fine but it sounded nice as well. im back to recirc now though
 
#7,704 ·
Im sort of curious to see the ages of the members who post about bov's. Im thinking that if you want the bov sound, you may be somewhere between 16-20 and if you think getting a bov is ricey, you may be in the 21+ age group. I just think that the bov sound is something that seems more appealing to the younger wrx owners out there and that you grow out of it with age. Im just curious thats all.
 
#7,705 ·
+1

I'm 29, I'm not so much against BOV's as I am BOV+MAF. They can be done, but there are other ways to get the whoosh sound if you want it. Hell, crack a window open at highway speeds - plenty of whoosh.
 
#7,706 · (Edited)
I own a 2006 WRX and I had a 100% atmospheric Blitz Super Sound BOV for about a month, when I first bought upgrades for my car. I bought it because I would hear it in movies, and on a EVO in town and I thought they sounded nice, and from what I heard they helped performance.

I kept the Blitz on for less than 1,000 miles. It's sitting in my garage in a ziploc bag.

During that time it backfired on almost every accelerate and let off. When I would accelerate hard and get up to 4,000ish at and let off completely the entire car would shutter like it sucked up a rabbit. I was running the orig. Stage 1 from COBB at the time.

When I would head down a windy country road, which I used to love racing down, the car would stumble after repeated release and application of acceleration throughout the twisties.

I took it off, changed the sparkplugs, ported all the piping I could get my hands on including the connections on my stock BOV. Installed the p&p'd stocker, reset the ecu, ran a new map that I tweaked, did the knock timer reset. It works great.

The stock sounds better than my Blitz! I'm running a Fujita F5 Comp Intake and it's quiet enough on hard accel that people can't hear it, but if I cruise up to a parking lot and do some minor let offs, it sounds like no other BOV on the market. F the wooshing sound give me the laser like sound of the stocker :)

Check the page in the sig for the video. The beginning has the hard acceleration, and later on a slow drive by. Stocker the whole time.

I love my car now.:thumbup:
 
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