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Discussion Starter · #1 · (Edited)
so I am unclear on why everyone is so opposed to BOV's. is it just a matter of tuning, couldn't that be solved with something like cobb ap or ecutek? I have read all the threads and most people say don't because it is bad but they really don't say why, like exactly why. I like the sound and I what a big loud hisssy BOV, what do I have to do in order to have one on my STi without make the world implode?


if it does make you run rich like stated below then if a person were to run an alky kit, which I think makes u run lean unless properly tuned for it, would this help?
 
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Makes your car run rich if u have a BOV on a Stock turbo..or stock STi i think. All i know it makes u run rich, and thats not a good thing.
 

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Yes makes you run extremely rich between shifts and your fuel economy will become worse. Trust me I had the same issue I bought my car that way it had a 100% venting turbo xs Bov and man was the car hard to drive and lost power in between shifts so I changed it out to a stock Bypass valve just listed to the majority they are right. Unless you are going with a turbo upgrade stick with stock hope that helps.
 

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Discussion Starter · #7 ·
WESTI said:
Omg Search Before Posting!!!!!!
and
guirgis2005 said:
search button is ur friend
READ BEFORE POSTING!!! I did search and in non of the posts did it offer an answer to my question. if you read my question it is weither or not this problem can be overcome with EM. maybe u 2 should read the post youself before posting replies about SEARCH when I said I have NOT found an answer to my question.
 

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Discussion Starter · #10 · (Edited)
this helped too, thnx to da keyzo

STi and BOV
It is common conception that STi and BOV don't mix. This is true to some level; however, the fundemental issue here MAF setup engin management system which is not STi specific and is common among 99% of production vehicles.

BPV/BOV neccessity/background:
At mid-high boost situations where the throttle is closed (i.e. shifting or simply letting off / decelerating) the turbo is still spining and generating compressed charged (boosted) air; if the throttle was to close suddenly and there was no way of releasing this pressure quickly enough this would send a shock wave strong back to the turbo compressor blades where simiply turbo would fail (destroyed).

Stock BPV (by-pass-valve) recirculates all of this pressurized air back into the intake trackt before the turbo after / after the MAF (mass air flow sensor).

Source of the problem with aftermarket BOVs in a nutshell:
The problem arises when after market BOVs vent all of the charged air out into the atomosphere instead of back into the intake trackt. Essentially what is happening here is that the air being vented off was already mesured for by the MAF thus ECU is going to supply the fuel for it to the engine. But we vented the air out of the system and the ECU does not know this. This causes a rich condition (flames shooting out the exhaust) and some cases it could be bad enough where the car could stutter/stumble.

What is the advantage of aftermarket BOV/BPV? Then why so many poeple use the after market units and are there any benefits minus the sound?
The factory unit was designed to be used with the factory turbo at the factory boost setting (14 psi). Above this some claim the unit leaks I tend to disagree; however, at high boost pressures (factory turbo can make up to 23 lbs of boost midrange and 17 lbs at redline) the factory unit may not be able to vent enough air quick enough to avoid the damaging shock get back to the turbo. Further since the factory VF39 gets out of its efficiency range at high boost recirculating hot charged air pre-turbo may not be the best thing.

Solution:

APS and other Dual vent by pass valves ~ These units essentially recirculate the air at partial thorttle low boost settings just like the factory unit and vent to atmosphere and recirculate at high boost. Essentially providing the best of both worlds. The still does experience a short rich condition but this is not something that is un-healthy for the system. Further the turbo can respool quicker; since it was never stalled or had a hard shock.

checkout the APS
 

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^^^having a 50/50 bov is still not the answer. if any air is released into the atmosphere your car's ecu is going to be thrown off.

i have to imagine if you get tuned for a bov you should be fine because there are plenty of big turbo guys running bov's fine. but i certainly would not run without a tune, and i would double check that your tuner can make your car run fine with one.


easiest way to hear the bpv noise, get an intake.
 

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^^good stuff
 

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evilSTi7 said:
^^^having a 50/50 bov is still not the answer. if any air is released into the atmosphere your car's ecu is going to be thrown off.

i have to imagine if you get tuned for a bov you should be fine because there are plenty of big turbo guys running bov's fine. but i certainly would not run without a tune, and i would double check that your tuner can make your car run fine with one.

easiest way to hear the bpv noise, get an intake.
+1 ... If you want a louder sound find out which intake make the most sound with the BPV... I believe its the Perrin intake but dont quote me on that... I have a K&N and did the whole intake silencer delete and i can hear the BPV perfectly.
 

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Yep...

KiR DieseL said:
+1 ... If you want a louder sound find out which intake make the most sound with the BPV... I believe its the Perrin intake but dont quote me on that... I have a K&N and did the whole intake silencer delete and i can hear the BPV perfectly.
Right on. I got the SPT intake, even kept the silencer in the fenderwell and re-attached the front intake piece. I hear it loud and clear in the car, windows up or down. Don't know if it's heard outside the car and I don't care. I did it for my amusement only :D
 

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white2006sti said:
Right on. I got the SPT intake, even kept the silencer in the fenderwell and re-attached the front intake piece. I hear it loud and clear in the car, windows up or down. Don't know if it's heard outside the car and I don't care. I did it for my amusement only :D
On WOT (or giving it some good gas) people can hear it.. i asked the other guys when ive been at meets :D
 

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evilSTi7 said:
if any air is released into the atmosphere your car's ecu is going to be thrown off.
Negatory on that. Your ECU will be open loop at WOT and when you yank your foot off the gas, either one. So it won't care in the slightest about the 1/2 second lean condition.

The short answer to how to correctly use a BOV on a draw-thru MAF setup is that it cannot vent during part throttle. The factory BPV does this extensively. That would cause an extended rich condition that could actually be troublesome. If you only vent on shifts, you'll be just fine.
 

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get the K&n typhoon intake, it will sound like a BOV
 

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Reek knows whuzz good
 

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My Cobb shorty was pretty loud. My APS cold air is pretty fast.
 

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Rootus^^^So would you recommend a 50/50 bov or something else?
 
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