---<<<(((The BIG BOV thread)))>>>---

hi there,
I was wondering if someone can tell me how to remove
the silencer on the BOV.......

thanks..........

[God]

There is no such thing as a silencer on the BOV. There's a silencer on the intake tract. It is in the fenderwell. Simply undo the fender liner and remove the two bolts holding it in place.

[PlatinumWRX]

Viper,

I can see where you would be confused. By removing the fender silencer, it becomes easier to hear the stock BOV.

Check out the tutorials section.

-Jim

[Sherb]

A friend of mine in his MR2 removed the hose that connected to the intake from the BOV. He closed off the intake and let the BOV hose vent to the atmosphere. He claimed it was real loud, like hearing the brakes from a bus. I thought I could do the same but it looks like its too much trouble .

[PlatinumWRX]

Umm, don't do that. The Stock BOV is not designed to be vented to the atmosphere. You will destroy it prematurely.

-Jim

[Sherb]

I wasn't planning to do it anymore anyway . But I would imagine that the BOV wouldn't care where it vents the pressure (either the intake or the air, how can it tell?). The only thing would be that your engine may run richer as the air loss calculated from the MAF went out into the air instead of going back to the intake. I'm still a newbie with turbo cars so I'm just relaying what I've read.

[NJSubieTech]

You dont want your bov venting to atmosphere - that will cause a loss of power. Take out that stupid resonator and youll be able to hear it better, along with the turbo spooling up.

Joe

[TerribleOne]

alright a bov vents pressure to the atmosphere. lots of people use it interchangably with bypass valve which is what our car comes with. bypass valve vents back into the intake.

as for the question as to if it is ok to just take off the hose and vent to atm. does anybody have a solid answer as to why the bypass valve will malfunction if done so. im not saying it will not prematurly malfunction but i would like to now what will cause it because this is an interesting topic to me. cause all your doing is taking a hose off the line which in my thoughts does nothing to cause it to break.

[PlatinumWRX]

Here we go. Another long post from clubwrx's resident MechE.

The "bypass valve" used interchangably with BOV (T1 is right, this is not correct) is designed to open and release pressure to a different (lower relative pressure) location in the intake manifold. It is not designed to vent to a zero pressure (atmospheric pressure) location and simply removing the hose will put too much of a pressure difference (Delta P) on the valve actuation unit (which is controlled by a vacuum pulse). This will cause it to fail prematurely, as I previously stated. Add to this the fact that it only opens occassionally because it has a very stiff spring in it and you can see why this will cause problems.

While a lot of people don't believe a BOV is a performance mod, NJSubieTech and I will ardently disagree with them. A high quality BOV (like the APS/Cobb Tuning unit, which is worth the extra $150) will allow the excess high pressure between the turbo compressor and the throttle plate (or butterfly) to be instantaneously released to the atmosphere when the throttle is snapped closed. This release of pressure still occurs with the stock "bypass valve," but much less efficiently.

A good BOV, not one that's just designed to make a neat sound, will protect your turbo from the sudden pressure increase during shifts, and allow it to return to maximum boost faster after a shift. This has been proven by NJSubieTech in races. The car with the BOV pulled evenly with the stock WRX until shifting into second, then the car with the BOV would start to get away with each upshift.

As far as harming the engine in anyway, would a Subaru technician put a BOV on his car if it was going to hurt it? Even Dan (God) has stated that all cars go lean when the throttle is snapped closed, whether it has a BOV or not.

The qualities of a good BOV are:
1) Dual-vent capability so that the BOV can mimic the stock unit during lower rpm upshifts
2) Stock mounting without any kind of adapter plate
3) An adjustment for full atmosphere to full intake vent-back
4) A large piston that moves completely out of the way when the throttle is suddenly released
5) All of the hardware necessary for installation
6) Directions for installation and tuning the unit

Of all of these qualities, the APS valve only lacks directions. It came with no directions what-so-ever. While a person of above average intelligence can figure it out, I firmly believe that everything, and especially car parts, should come with directions. Whether or not you choose to use them should be up to you.

NJSubieTech, feel free to correct me if I am off base at any point in this very long post.

-Jim

[BigRich]

I've got one of those dual-vent GFB BOV's. Using the dual-vent option is nice, but now I want more noise. It's time to seal off the vent on the BOV leading to the intake and go with 100% atmosphere vent.

My question is, what is the best way to seal off the remaining vent to the intake? ...or with what? Is there a part I need?

Thanks

-- Rich

[dug-e-fresh]

i just sent you an e-mail....actually 2.

there are in fact 2 pieces that are supplied with the GFB BOV that allows for 100% vent. A plug and a plate. The plug is most important, the plate less important. You need the plug....

doug

[BigRich]

I gots no plug... Arrrgh!

Anyone have an alternative? ...or a spare plug?

-- Rich

[JDMario]

ever since i changed to synthetic. my bov seems quieter. and i get that skipping sound more often (it goes pah, pah, pah not pshhh)

[PlatinumWRX]

mario,

I never heard my BOV skip until I switched to synthetic oil. I have absolutely no idea what one ahs to do with the other! As far as loudness, I don't think that has changed.

-Jim

[JDMario]

so your skips too?