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Old 11-17-2003, 07:42 AM   #1
TheMadScientist
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Default $0.16 BOV mod

OK so I am a cheap sob. I want to run over 18psi on my 16G but the stock BOV opens around that pressure. So what are my options?
1)Buy an atomsphere BOV.
I borrowed one and got really sick of the noise I like stealth.
2)Buy a recirculate BOV.
I am cheap and don't want to spend $200+ on one.
3)The $0.16 mod
Very cheap and stealth this fit the bill perfect. Still 100% recirculate so no idle problems or rich between shift problems. This will allow you to run as much boost as you can throw at it and not open. The one drawback to this that I have found is that around 5-10psi when you shift you will get a real quick real short surge. This will not happen at higher boost levels.

The Mod:
Take off the BOV and look at the face that mounts to the IC. You will see two holes a big one and a small one. The big hole is the valve that releases the pressure the small hole is a boost signal line.
What I did was to take a 1/4-20 tap and drilled out the small hole and tapped it. Be careful to not let any shavings go into the hole. I held the BOV upsid down while drilling and tapping. Then I took a 1/4-20 set screw put teflon tape on it and sealed off that hole.
Then on the body of the BOV you can see where that signal hole goes through the casting. You want to drill in to that signal line and vent it to atmosphere. There is a bung cast into the BOV body to do this.

I have some pics that I will try to post tonight. Any comment or questions?

Mark
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Old 11-17-2003, 08:01 AM   #2
busky2k
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So how does it feel after you've done the mod? Holds boost better?
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Old 11-17-2003, 08:33 AM   #3
Rickyh
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Could you just crush the cap a little? I have heard of people doing this on dsm's to get them to hold more boost?
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Old 11-17-2003, 08:55 AM   #4
TheMadScientist
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Quote:
Originally posted by busky2k
So how does it feel after you've done the mod? Holds boost better?
There is nothing that I can feel that is different. Except that the BOV now holds a rock solid 20psi. I am sure that it will hold more but my boost gauge only reads to 20psi.
Crushing the top would probably work too. But eventualy you will run into the same problem at higher boost. From what I can see (I cut open another stock BOV) The more boost you run the tighter the BOV will close with this mod.
There is a diaphram inside the BOV before this mod the pasage that you block allows boost to be equal on both sides of the diaphram and relies on the spring to hold it closed. After the mod you have boost and the spring pushing the BOV closed with atmosphere trying to push the valve open so the more boost you run the tighter the valve closes.
Hope that makes some sense.
Mark
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Old 11-17-2003, 09:20 AM   #5
Wheeler Bement
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does it still dump the boost as fast as it should between shifts?
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Old 11-17-2003, 10:57 AM   #6
TheMadScientist
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Quote:
Originally posted by Wheeler Bement
does it still dump the boost as fast as it should between shifts?
Depends on how much boost. At lowwer boost levels 5-10psi I get a very very brief surge less than 1/2sec then vents normally. It is fine at higher boost levels 15-20psi. So far ther are no driveabilty issues.

Mark
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Old 11-17-2003, 11:44 AM   #7
garface
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You can always buy an STi BOV for under $100. My engine is putting out over 20 psi and never had a problem with the stock STi BOV. I might even sell mine, I'm still trying to decide between keeping the TXS RFL or keeping the JDM STi BOV. Actually, I might just sell them both. Let me know if you'd be interested, definately cheaper than an aftermarket one.
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Old 11-17-2003, 03:08 PM   #8
PaulRex
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I crushed my stock BOV, old DSM thing.. sounds alittle simpler than what you did.
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Old 11-17-2003, 03:12 PM   #9
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Quote:
Originally posted by garface
You can always buy an STi BOV for under $100. My engine is putting out over 20 psi and never had a problem with the stock STi BOV. I might even sell mine, I'm still trying to decide between keeping the TXS RFL or keeping the JDM STi BOV. Actually, I might just sell them both. Let me know if you'd be interested, definately cheaper than an aftermarket one.
Arn't the STI BOV springs less stiff than regular usdm wrx bov springs? that is what rallispec reported when they tested a V7 sti BOV vs. a MY02 usdm bov. They said it was actually less stiff maybe to react quicker.
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Old 11-17-2003, 05:47 PM   #10
Schleppy
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You're the mad scientist Mark
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Old 11-17-2003, 06:20 PM   #11
Greg Sharpe
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Yeah, the STi recirc BOV has a softer spring and is lacking the boost signal port. The divit for the port is there, but it isn't drilled all the way through.
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Old 11-17-2003, 06:27 PM   #12
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So this mod changes the WRX BOV into an STi BOV but with a harder spring?
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Old 11-17-2003, 08:05 PM   #13
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Talking

Here are the pics.
Attached Images
File Type: jpg block this hole.jpg (23.0 KB, 7753 views)
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Old 11-17-2003, 08:06 PM   #14
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I have more but these two should do.
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File Type: jpg drill this hole.jpg (25.6 KB, 7378 views)
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Old 11-24-2003, 02:07 PM   #15
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I am going to do this very soon...
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Old 11-24-2003, 05:57 PM   #16
n2xlr8n
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I wacked mine with a small ball-peen....good to 24 psi @ 7200 so far.
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Old 11-25-2003, 05:29 PM   #17
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Any updates TheMadScientist?
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Old 11-25-2003, 11:10 PM   #18
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Quote:
Originally posted by n2xlr8n
I wacked mine with a small ball-peen....good to 24 psi @ 7200 so far.
Not to hijack the original idea, but what does "wacking" the valve do? Are you hitting the face of the valve? Does it cause any notable problems for regular driving.
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Old 11-26-2003, 05:50 AM   #19
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Quote:
Originally posted by AjIsDope
Any updates TheMadScientist?
Running fine and holds more boost than my gauge will read.
I did one for Davenow yesterday. I hope he will post with his results.
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Old 11-26-2003, 06:41 AM   #20
Equilibrium Tuning
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Why not get an STI BPV? It looks like it should hold higher boost no problem and should work better at lower boost as well.

-- Ed
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Old 11-26-2003, 08:32 AM   #21
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Quote:
Originally posted by Vaus
Why not get an STI BPV? It looks like it should hold higher boost no problem and should work better at lower boost as well.

-- Ed
Because I am a cheap SOB. This cost me 16 cents the Sti BOV is around $100.
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Old 11-26-2003, 09:31 AM   #22
tmarcel
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Quote:
Originally posted by TheMadScientist
Running fine and holds more boost than my gauge will read.
I did one for Davenow yesterday. I hope he will post with his results.
How much boost are you trying to acheive?
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Old 11-26-2003, 09:41 AM   #23
TheMadScientist
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Quote:
Originally posted by tmarcel
How much boost are you trying to acheive?
25psi tapering to ~21psi at redline.
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Old 11-26-2003, 10:47 AM   #24
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Quote:
Originally posted by TheMadScientist
25psi tapering to ~21psi at redline.

I never thought about it until recently but how much boost is safe to run on the EJ205?
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Old 11-26-2003, 10:49 AM   #25
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I have no idea. But I have been running ~20psi on my daily driver for ~3 months. I want to melt or break the motor so I have an excuse to tell my wife that I need another one.
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