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Old 01-08-2014, 01:28 PM   #651
New88
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Thanks for the writeup Dave. I am completely new here, and just read this entire thing, as well as Unabomber's FAQ's. It seems a LOT of posters here spouting off about how horrible BOVs are, didn't even take the time to read anything!

I do have one question though, that I haven't seen addressed anywhere where BOVs/BPVs are being discussed, is that the BPV takes the air from between the compressor and the engine, and dumps it before the compressor, after the MAF sensor.

The piping leading up to the compressor does not have any type of backflow prevention (is open to the atmosphere at the filter), so when the air enters (from the BPV), it has 2 choices: go to the compressor, which is now only running on momentum, or go to the atmosphere. Air will take the path of least resistance and flow mostly toward the atmosphere, and back out apast the MAF sensor (so that already metered air idea doesn't hold much girth with me, at the moment).

Has anyone looked at this? I am a marine systems designer/engineer, and have drawn up a diagram of the system to ask a few coworkers. The most benefit we can see, would be from recirculating the air, as that the air has already been through the intercooler, and cools some more as it joins again into the intake (expansive cooling), thus cooling the compressor/making it slightly more efficient.

Sorry for the long post, and reviving an ancient thread, but I haven't seen anybody address this.
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Old 01-24-2014, 04:08 PM   #652
mephistomarius
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love my go fast bits 50/50 blow off valve, lol its been on my car since 02!
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Old 01-24-2014, 04:26 PM   #653
AFP520
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Quote:
Originally Posted by New88 View Post
Has anyone looked at this? I am a marine systems designer/engineer, and have drawn up a diagram of the system to ask a few coworkers. The most benefit we can see, would be from recirculating the air, as that the air has already been through the intercooler, and cools some more as it joins again into the intake (expansive cooling), thus cooling the compressor/making it slightly more efficient.
Air was never the problem with a BOV. It's the fuel. You cannot tune/modify the ECU to account for vented air, so the car will always inject that extra fuel and you will get the rich spike for under a second.

I believe a speed density system changes the whole way injection works and that's why you can go either recirc/vented without issue.
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Old 01-27-2014, 02:43 PM   #654
asticklerr
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This might have already been answered, but I want to be 100% sure. I just bought the Perrin recirculating BOV for my 2012 WRX, and I was just wondering if I need a tune, or if theres anything I should do. And if anyone else has this BOV, what setting are you running on it? Softer, or harder? lol Thanks!
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Old 03-03-2014, 10:44 PM   #655
iknowanoah
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no bov sleepin
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Old 03-07-2014, 07:18 PM   #656
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can i ask what running rich means?
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Old 03-08-2014, 02:28 PM   #657
Omega9120
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Love it, great post.
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Old 03-09-2014, 09:16 PM   #658
ndprsha
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Default Thanks for the write up

Thanks for the write up on this
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Old 03-28-2014, 01:26 PM   #659
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Quote:
Originally Posted by Davenow View Post
See, I know its a confusing message.

They are and they arent. There are ups and downs. If you are worried about performance, and dont NEED the noise, its best to just stick with stock.

It all comes down to

What are you looking to do? Like how much boost, what kind of setup
What are you looking for? Noise?
DID YOU BUY A QUALITY VALVE?
If so
DID YOU ADJUST IT PROPERLY?

Its not that they are "fine" its that they are nowhere near as bad as people like to make them out to be. And that 99% of the time when someone is making them out to be bad, they are making statements that just arent true, and ignoring the larger problem of leaks.

rich wont hurt you. its a split second and its not that rich. LEAKS will hurt you. Less power, and can kill the turbo over time.


How come people have nightmares of being rich for a second ? Dont formula 1 cars change maps to run rich at certain times in a race to make more power ? not trying to be a jerk just like to know as much as i can.

Last edited by Senio; 03-28-2014 at 01:53 PM. Reason: grammar
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Old 03-28-2014, 01:26 PM   #660
Senio
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Quote:
Originally Posted by jwassil7 View Post
can i ask what running rich means?
more fuel than air. i believe.
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Old 03-29-2014, 10:20 AM   #661
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Quote:
Originally Posted by Senio View Post
more fuel than air. i believe.
Correct.

"Perfect stoichiometry" is a ratio of 14.7 air to 1 fuel.
Anything above 14.7 is considered lean and below 14.7 considered rich.

Quote:
Originally Posted by Garrett Turbos
For Example:
15.0:1 = Lean
14.7:1 = Stoichiometric
13.0:1 = Rich
Turbo cars run happier on the rich side of AFR, within reason.
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Old 03-29-2014, 08:52 PM   #662
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I have a 2012 wrx tuned TP Stage 1 with a forge performance recirc valve. I noticed that that idle after installing it now drops much lower than before then picks up. It almost always happens when the car is given a little bit of gas then released. Little help!
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Old 03-29-2014, 09:14 PM   #663
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it's leakin
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Old 03-29-2014, 09:21 PM   #664
JDMasfcuk
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Quote:
Originally Posted by user1029 View Post
it's leakin
Positive? What's the best test to do? I'm guessing a spray bottle around the area where it bolts right up to the intercooler?
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Old 04-05-2014, 09:46 AM   #665
sxesubaru
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Definitely a good read.
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Old 04-13-2014, 04:57 AM   #666
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Thanks !!
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Old 04-14-2014, 03:48 PM   #667
A Fatal Ode
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Quote:
Originally Posted by AFP520 View Post
Air was never the problem with a BOV. It's the fuel. You cannot tune/modify the ECU to account for vented air, so the car will always inject that extra fuel and you will get the rich spike for under a second.

I believe a speed density system changes the whole way injection works and that's why you can go either recirc/vented without issue.


Are there any pros and cons to running a full recirc or just going atmospheric with speed density? Other than a simpler piping configuration. ...and noise. ?

as in, does one do the job more efficiently than the other?

again, SD... not MAF.
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Old 04-22-2014, 06:36 AM   #668
scylar
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Good write up.
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Old 04-24-2014, 07:22 PM   #669
endeeeejay
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Thanks for the write-up... taking notes.
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Old 04-24-2014, 11:05 PM   #670
kryptea
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great FAQ!!!
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Old 05-02-2014, 08:12 PM   #671
BobbyDUBRX13
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Anyone have thoughts on the GFB respons hybrid BOV? and right now I just have the sf intake cat back exhaust and running a stage 1 map on the AP.. I'm planning on replacing the tmic with a process west TMIC and I think this valve would be the best so I can set it up as a 100% recirculating or maybe do a 20% atmospheric and 80% recirculating what do you guys think
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Old 05-11-2014, 12:42 AM   #672
Rob_STI_PNW
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i think if you are deadset on a BOV get a full recirc one until you get a bigger turbo like Cobb XLE...
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Old 05-11-2014, 01:14 AM   #673
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TiAL for me every time.
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Old 05-20-2014, 06:54 PM   #674
Lionscage
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Just the info I needed, thanks!
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Old 05-21-2014, 01:05 AM   #675
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So I have a 2006 WRX with a cobb access port stage 1 install, I don't have a BOV and I am considering adding one. Any tips, good/bad experiences that you can share with a young person.
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