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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 06-21-2007, 11:12 AM   #1
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Angry BOV not B, O, or V'ing HELP

My new greddy Knock off BOV is not venting at all. I put it on a flange I had welded on my crossover, and teed it into the vac line for my WG. And even with the nut fully removed i dont think it is venting. Not for free revving not with boosting. Could the BOV VTA just be to quite for me to hear? Should i take it apart and look for problems. Any ideas.
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Old 06-21-2007, 11:15 AM   #2
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The BOV needs to see both VAC and Boost.

If it isn't blowing off you'll hear compressor surge (turkey gobble).
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Old 06-21-2007, 11:15 AM   #3
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yeah, source line needs to be off manifold, not turbo. the vacuum created when the TB is closed is what helps pull the valve open.
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Old 06-21-2007, 11:17 AM   #4
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stuck your finger in there and checked for mechanical action?
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Old 06-21-2007, 11:18 AM   #5
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If you can remove the pipe easily, buy some PVC piping caps that will fit in the current silicone connectors, seal the pipe with the caps, put a tire valve on a cap, then pump the psi you run through a compressor and see if it opens.

That way you can test it on a work bench without the engine noise or having to drive the car.

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Old 06-21-2007, 11:54 AM   #6
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Even with a K&N air filter on the exhaust my knockoff Greddy BOV is loud enough to hear. You'll only get it when letting off the throttle under boost- not just sitting in the garage revving it.

Braineack is right in that the line on it needs to be connected to the intake manifold post-throttle. That's the only place you'll see vacuum.

When I did mine, I opened it up and removed the center (smaller) spring from the mechanism. That made it much more responsive and somewhat quieter, though it does vent (well, inhale technically) at idle. So this trick won't work for those using AFMs.
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Old 06-21-2007, 12:22 PM   #7
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I dont have a turbo feed for MY WG all my vac lines come post TB. I might just take the spring out of it i tried and at idle with -20 vac i dont feel anything that would indicate it is open i have the adjustment screw fully removed now. I took it for a drive and it still seemed to gobble on me abit just maybe a little quiter. Hopefully the spring deal fixes it i dont want to have to pony up any more money for this stuff. Thx guys I hope that with your help i can make my first BOv work for me.
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Old 06-21-2007, 12:24 PM   #8
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I think it is generally recommended to have the BOV on it's own line from the TB. Give that a try too.
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Old 06-21-2007, 01:25 PM   #9
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if it's delaying in opening and the BOV has a second port on the lower portion, hook that up to a boost-only source as well as the boost/vac upper fitting.
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Old 06-21-2007, 02:02 PM   #10
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Quote:
Originally Posted by magnamx-5 View Post
i have the adjustment screw fully removed now.
On mine anyway, removing the adjustment screw altogether creates a massive vacuum leak that would prevent the unit from working.
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Old 06-21-2007, 02:11 PM   #11
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How big a Vac line are using?
Some are more sensitive to size than other others. My little bosh recirc runs off any little 3mm line, But when I switched to the turbo XS I needed at least 5/16" to make it function properly, which sometimes means drilling and tapping the IM for a dedicated line.
Are using the source off the back underside of the IM? Or does your year car have one? The 1.8's have it, it's just capped off, not sure on the 1.6's...
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Old 06-21-2007, 07:34 PM   #12
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Hmm Joe you might be onto something there.
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Old 06-22-2007, 02:38 AM   #13
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I am also having trouble with my BOV. It is just the stock mitsubishi BOV. Anyway, it only seems to vent if there is a lot of vacuum. If I only partially lift on the throttle during boost, I hear the compressor surge, but no BOV. I think it is a bit old and I'm wondering if there might be something wrong with it.
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Old 06-22-2007, 02:08 PM   #14
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Quote:
Originally Posted by magnamx-5 View Post
Hmm Joe you might be onto something there.
Easy enough to test- just listen near the hole while the engine is running, plug it with your finger, etc...

When I first got mine I did a lot of experimenting with it on the bench using a hand-held vacuum pump and gauge. I found that the total adjustment range of the screw was fairly small, and that in the stock configuration it took about 25" of vacuum to open the valve. (And it never did open fully, as this was all my hand-held vacuum pump could produce.) Also, backing the screw out almost all the way was exactly the same as having it removed and plugging the hole. If you dismantle the valve and inspect it you'll see that the screw disengages from the spring retainer before it comes all the way out.

There are two springs inside, and removing the center (smaller) one brought the valve to the point where it starts to open at around 15". Thus, it leaks massively at idle, but closes as soon as I get on the throttle. This is fine since I have no AFM, so I just made an adaptor and stuck a filter on it. This also quieted it down even further, which is a plus for me.

I suspect (though I did not test for this) that you might be able to run with one spring but shim it with washers to fine-tune the BOV such that it does not leak at idle (around 19-20" typically) but is still softer than the out-of-the-box setup. I honestly don't know if you will be able to hit this point and still have full travel available on the piston, but it's worth a shot.


Quote:
Originally Posted by rharris19
I am also having trouble with my BOV. (...) I think it is a bit old and I'm wondering if there might be something wrong with it.
It's quite possible that the rubber diaphragm inside is just old and has started to crack. If you have access to a pump-type vacuum tester, you can do a leakdown test on it. Just hook up the pump to the BOV and draw a vacuum until it opens. Then stop pumping and see if the vacuum gradually drops or the piston starts to close again.

Speaking from limited experience (sample size = 1) I have had very good success with the knock-off "Greddy Style" BOVs that are sold by various eBay vendors. Specifically, this is the valve that I bought: http://cgi.ebay.com/ebaymotors/ws/eB...romZR40QQfviZ1
That particular seller is no longer around, but there are plenty of others. Just search eBay Motors for RS BOV and you'll get hundreds of hits. There are two general styles of Greddy-clone BOVs. The "S Type" has two vacuum ports- one above the diaphragm (post-throttle) and one below the diaphragm (pre-throttle).

Some people have complained about these being finicky, but I can't see why. The "RS Type" appears to me to be the exact same design but instead of a vacuum nipple in the lower position there is simply a small vent hole. Ergo: an "S Type" should behave identically to an "RS Type" valve if you leave the lower port open.
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Old 06-22-2007, 10:59 PM   #15
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Thanks Joe i used the vac pump on it and it was a leak source os i pluged it with a shorter bolt still no driving impresions yet but at 20 inches mercury it takes little effort to open so it should vent boost once i go into vaccuum wich is what it is supposed to do thanks guys i think this might be right now.
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