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.
FMIC Bov - $210 shipped
TMIC bov- $236 shipped
^Pricing for APS BOV @ Thewrxstore.com
All APS stuff is TOP OF THE LINE, nothing beats it that i have seen..Some of their items are pricey but.. these will outperform any other BOVs.. same thing as a forge exept w/a little more adjusting/sound options, i think.
drop me a mail if anyones interested.. going to try and work a deal on these to maybe lower the price or get some free stuff..somehtin like a GB yayforyay@hotmail.com
which color is which tension? how many different springs should i ask for more when i call and order this thing? i don't wanna have this "low rpm leak" thing and have to order more. ya know?
The 100% Forge that I have does not flutter.
Another point that should be made about the Forge is that they are a completely rebuildable item and Forge supports with all spares. I needed to get the 'blue' as opposed to the 'yellow' spring and they sent if for free in 3 days from their US distributor.
Very happy with it!
Another point to note - it is a lot smaller that some other BOVs
_____________________
To clarify the venting issue I had - I do not like the BOVs that open when you are in neutral and rev to 3000 rpm and open when you release the throttle - that is where a lot of the problems occur (IMHO).
I get slight venting in neutral only if I rev over about 5500 rpm.
which color is which tension? how many different springs should i ask for more when i call and order this thing? i don't wanna have this "low rpm leak" thing and have to order more. ya know?
yellow is soft or easy venting
blue is the next stiff-est or harder venting (he he I said STIFF!!)
I am not sure of the red - probably harder still. They fit the yellow which would be the most conservative setting. It is worse not to vent than to vent too much. I will email George and ask him. Cheers,
how long has that intake been on there....cause that can make a DRAMATIC increase in turbo noise....once i cut off my silencer and bottom half of my airbox and just threw a k&n in there it was like night and day in respect to turbo noise.....if your wastegate was stuck open you wouldnt be really making too much noise....is your car idiling crappy? if so maybe check the wastegate recirc hose...but that should only blow off when u shift...otherwise i dont know what to tell u man, bring it back and bring it back some more until u figure out whats up ...i am like very sure its just ur turbo though. contact one of the texas guys...one of them would possibly come down and listen to the noise for you...i would but that woudl be a looooooonnnggg drive haha good luck man im sure its just the turbo
At first thought, this sounds like an Uppipe leak has developed, however, my leak would leak at the same boost levels reguardless of what gear I was in....
My second idea, is that it could be your accessory belts slipping. I had this problem with an AC belt in my Mitsu., If I accelerated slowely, it wouldn't make a noise, but when I punched it the AC belt would slip on the pully and screetch pretty bad. You can try tightening your idler pulley.
I will try to find someone near me that can help. I will check for uppipe leakage. And I thought it was the AEM alternator pulley. So i took that off, but the noise is still there. how do you check for uppipe leakage without moving the car?
My guess is its a leak. Not neccasarily your uppipe but one of those gaskets in that area. My car developed that and it would only make noise while on boost and would not go awan no matter how warm the car was. I re did my uppipe install and my uppipe gasket looked perfectly fine after I retorqued everything i still have a very small leak that goes away once warm. I think it may be from my manifold to block gasket though.
from what hes describing its not a leak guys..come on if u had a leak for 6 weeks or months or whatever he said...that gasket would be totally gone and it would be like horrendously loud squealing..
I did have a leak for 2 months just like he is describing and all the gaskets were still there. Im not saying it definetly is a leak but your reasoning does not rule out the possibility of a leak.
the noise is loud enough for me to hear over my stereo blasting. If I had an exhaust leak.. how do I find out myself and how long would it take for somethin to get messed up?
what does this flutter sound like...i am hearing the wastegate quite a bit now but am not sure what this flutter would be (if i do in fact have it)....
george is also sending me some shimms (spacers ?) with my new spring and said that i should try them first....
this is the email that he sent me...
I've sent out your spring today. I've also included 2 shimms. I would suggest you try the shims with your current spring first and see how that works. If you're still fluttering after 2 shimms then go with the red spring.
Here is the email I rx-ed from George regarding the spring colour vs tension and the shims.
"
Green: soft
Yellow: medium/soft stiffness
Blue: medium stiffness
Red: stiffest.
The flat discs or shims are just for that. Pre-loading. We've found
that some of the WRX's respond differently to the new valves. Not sure why, it just seems to be an idiosyncrasy of the brand. Anyhow the shims allow the user to "fine-tune" the spring tension in the event that the spring alone is not working properly. This happens relatively infrequently but enough for us to offer a solution for when it does.
I don't have any printed material on how to tune and service the
valves but it's a very easy operation. The top of the valve simply
twists off. The springs and piston on found underneath. The shims are placed in the top of the piston and then the spring is put back on top of the shims. The top is then screwed back on, the valve re-installed and the user can then test the results. Usually this will take a couple tries but once it's set, it will not need any further adjustment unless the owner makes changes to the car that effect the valve such has increased boost.
I hope this has answered your questions. Please feel free to
contact me if you need any more information..
Regards,
George Osmun
Director Sales & Marketing
Forge Motorsport Inc. www.forgemotorsport.com
Phone - 321-689-0972
Fax - 321-697-0060
"
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