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11-17-2003, 07:42 AM | #1 |
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$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 |
11-17-2003, 08:01 AM | #2 |
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So how does it feel after you've done the mod? Holds boost better?
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11-17-2003, 08:33 AM | #3 |
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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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11-17-2003, 08:55 AM | #4 | |
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Quote:
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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05-23-2005, 06:08 AM | #5 | |
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So you could be holding 29389283 psi, but you have no clue, right? You only know its over 20... watch out. |
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05-23-2005, 07:39 AM | #6 |
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^^^ I'd venture a guess that he's running a better boost gauge now since the post you mentioned is from 03', and it was on a totally different car ...
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05-23-2005, 08:11 AM | #7 | ||
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Quote:
TMS |
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05-24-2005, 12:09 AM | #8 |
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Air Power Systems Pty Ltd has this to say about their blow off valve:
APS BOV development: We are often asked why we developed our own blow off valve when there are so many on the market. Quite frankly APS had not found a blow off valve for the WRX/STI that offered the level of performance required. With a large turbocharger, releasing pressure from the turbine compressor wheel when the throttle is snapped shut is critical not only for turbocharger response, but for turbocharger longevity. A huge volume of air must be passed through the blow off valve as soon as the throttle is closed. Most blow off valves have limitations in their design that inhibit the level of performance we demand. Piston/bore diameter and venting ports are often too small and surprisingly, most will not fully expose the exhaust ports when fully opened. Ultimately, the need for a truly high performance blow off valve specifically designed for the WRX/STI needed to be satisfied. |
11-04-2007, 01:26 PM | #9 | ||
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First of all, please excuse my bad english, I'm coming from Austria
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11-11-2007, 11:28 AM | #10 | |
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I did this mod now too, but I wasn't happy with the hole getting unfiltered air into the BOV. So I did the Mod this way: I love that PFZISCHHHHH at shifting |
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11-17-2003, 09:20 AM | #11 |
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does it still dump the boost as fast as it should between shifts?
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11-17-2003, 10:57 AM | #12 | |
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Quote:
Mark |
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11-17-2003, 11:44 AM | #13 |
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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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11-17-2003, 03:08 PM | #14 |
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I crushed my stock BOV, old DSM thing.. sounds alittle simpler than what you did.
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04-25-2008, 10:53 AM | #15 |
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11-17-2003, 03:12 PM | #16 | |
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11-17-2003, 05:47 PM | #17 |
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You're the mad scientist Mark
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11-17-2003, 06:20 PM | #18 |
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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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11-17-2003, 06:27 PM | #19 |
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So this mod changes the WRX BOV into an STi BOV but with a harder spring?
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11-17-2003, 08:05 PM | #20 |
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Here are the pics.
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11-17-2003, 08:06 PM | #21 |
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I have more but these two should do.
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11-24-2003, 02:07 PM | #22 |
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I am going to do this very soon...
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11-24-2003, 05:57 PM | #23 |
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I wacked mine with a small ball-peen....good to 24 psi @ 7200 so far.
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12-06-2004, 05:02 PM | #24 | |
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04-26-2005, 12:18 AM | #25 | |
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