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Old 07-03-2006, 11:34 PM   #21
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Quote:
Originally Posted by ThePass
Also, two of the 3 pics show the valve mounted near the throttle body - but one of the pics:
http://www.bellengineering.net/Image...kit_front3.JPG
Has the valve mounted on the drivers side of the engine bay at the end of the recirculation pipe nearest to the MAF - so there is nothing keeping air from going into the pipe near the throttle body. This seems like it would be terrible for airflow since air would travel up that pipe and as it almost gets to the throttle body, there is a whole seperate pipe that will get filled by air - with nothing keeping it from getting into that recirculation pipe because the block - the bypass valve, is on the far side of the pipe.

Seems awfully bad for airflow to me... any one else think so or do I not understand things correctly?
-Ryan
Filling up that tiny pipe with boosted air shouldn't lead to any measurable decrease in throttle response or performance. I'd not worry about it, especially since Corky Bell designed it.

Secondly, you don't need to fashion a hard pipe like that, nor do you need to mount the bypass valve so far from the throttle body if you don't want to. This pics show roughly the same procedure and pieces I used to mount the Bosch bypass valve to my parents' Greddy kit, only, unlike these pics, I mounted the bypass in the correct direction (reverse of how it's shown here): http://www.15psi.com/BOV.htm

It was like ~$65 in parts and ~30min. of my time to install.
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Old 07-04-2006, 05:49 AM   #22
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Quote:
Originally Posted by bripab007
Dude, tons of people have shown the running VTA bypass can (not always, but can) causes drivability problems.
Ya = I've noticed that the car wants to turn left and right more often with it. Real loose front end, like my tie rods have fallen off!
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Old 07-04-2006, 10:23 AM   #23
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Quote:
Originally Posted by LOLA - 92
Ya = I've noticed that the car wants to turn left and right more often with it. Real loose front end, like my tie rods have fallen off!
Eh?
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Old 07-04-2006, 01:24 PM   #24
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Quote:
Originally Posted by ThePass
What kind of driveability probelms specifically? Idle problems I would expect if using a low quality bov that leaks at idle... but what else are you referring to? I'm curious as I would prefer to use a VTA bov for the simplicity but don't want to do it if it means a loss in performance or bad driving characteristics.

-Ryan
I have a Forge VTA BOV, it's a diaphragm type BOV. It leaks at idle and makes it sound all lumpy, it's one with a filter around the vent. With a VTA and an open element air filter, you'll still get a little whispering of the BOV, it just won't be that obnoxiously loud PSH! sound. Kind of like you you can hear the turbo spool up, you'll hear the BOV in a recirc.
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Old 07-04-2006, 02:46 PM   #25
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Quote:
Originally Posted by firedog25
I have a Forge VTA BOV, it's a diaphragm type BOV. It leaks at idle and makes it sound all lumpy, it's one with a filter around the vent.
It'd be interesting to see just how lean you're running at idle and cruising conditions when that VTA bypass valve is sucking in un-metered air.
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Old 07-04-2006, 09:33 PM   #26
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So that www.15psi.com website - is the recirculating BOV on there a good unit and is that a good kit or is that just somebody who doesn't know too much making shoddy stuff in their garage? It looks ok...
-Ryan
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Old 07-04-2006, 11:10 PM   #27
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Yes, the kit of 15PSI's website is incredibly easy to replicate yourself, for a bit less money (maybe $60-70 total, or less if you already have a drill press with large bit, etc.). There's nothing particularly shoddy about it, though; don't try to overcomplicate what a bypass valve is, be it recirculating or otherwise: it's just a very simple valve to divert air through some tubes.

That particular Bosch bypass valve has been used for years on Porsches, Saabs, VWs, Audis, etc. There's nothing sketchy about it.
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Old 07-04-2006, 11:19 PM   #28
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Quote:
Originally Posted by LOLA - 92
DOG -
Are you implying that running VTA makes your car run "PIGGY RICH"?
I've never heard of this, but I would be interested if others have this symtom from running VTA....
It will make the engine run rich, during the brief period when the valve is open, if and only if you are using an AFM or MAF sensor which directly measures the volume of air entering the system.

Those engines which use MAP as their primary fuel metering sensor will not suffer this problem, since they have no concept of how much air is being drawn through the intake- only how much of it is actually getting into the manifold.
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Old 07-05-2006, 02:56 AM   #29
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Flying Miata sells this blow off valve on their website:
http://www.flyinmiata.com/index.php?...umber=05-90110
It's from GFB and it is a VTA unit - but they specifically say that it has a special piston ring that makes a perfect seal and: "this means the valve can be used on a car that uses a MAF or AFM to measure airflow"

Are they just referring to the fact that it seals perfectly so it doesn't leak at idle, or are they somehow saying that this unit will work for a MAF metered car somehow? They sell a different bypass valve that is a recirculation unit, so it doesn't look like this bov can be used as a recirculation type...

-Ryan
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Old 07-05-2006, 03:02 AM   #30
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Quote:
Originally Posted by bripab007
It'd be interesting to see just how lean you're running at idle and cruising conditions when that VTA bypass valve is sucking in un-metered air.
Well, I don't have a wideband yet so I couldn't tell you. It runs pretty good at cruising conditions, but it idles like a retarded monkey with Parkinson's. ALMOST stalls every time, I'm pretty good at heel-toe so I just use that at stop lights.
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Old 07-05-2006, 11:51 AM   #31
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So, why are you using that VTA bypass on your car since it's causing such significant drivability problems?
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Old 07-05-2006, 02:16 PM   #32
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Me? Because I'm stupid and didn't hear anyone whining about drivability issues. I'm looking for the Porsche turbo recirculation valve now. It's a brass piston type valve, pretty solid from what everyone says. I've found some aftermarket replacements for a relatively decent price (sub-$150) so I may actually go with that since they're aluminum instead of plastic. My cat needed replacing anyways, so running piggy rich isn't a big deal to me except sometimes my exhaust reeks of gasoline even after parking and I'm used to replacing my 02 sensor because I had a small head gasket leak last year.

I need to re-find those though, I'll post links when I do.
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Old 07-05-2006, 03:04 PM   #33
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Here's the Bosch valve for $40: http://www.paragon-products.com/prod...110.337.50.htm

I think I bought mine for ~$50 shipped. I've said it before, and I'll say it again. If Porsche, Audi, VW, Saab, etc. saw fit to use these in OEM applications with warranty concerns and the like, I see no reason to believe that they'll break because they're plastic. When you've actually held it in your hand, you quickly realize it's not a fragile piece of plastic.

BEGi also sells a nearly identical one, although I'm not sure if it's Bosch or what: http://www.bellengineering.net/Pages...ata_parts.html
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Old 07-05-2006, 03:13 PM   #34
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Firedog: Temp solution = http://www.jgstools.com/turbo/oav.html

Easy way to Reirc.:



tools needed:
jb weld
drill - tap and bits
threaded pipe

My bov is recirc. and is still fairly loud
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Old 07-05-2006, 03:39 PM   #35
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What size of bit, tap and pipe nipple did you use to do this?
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Old 07-05-2006, 04:08 PM   #36
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actually, it was a 1" pipe, and I used a 1" hole saw. That's it, screwed in tight and JB welded it. The hardest part was sourcing the heater hose to fit. It's 1.25" OD. Matched the opening of my bov.
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Old 07-05-2006, 04:12 PM   #37
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You don't have to be incredibly precise with it; just make sure the diameter of the pipe is roughly 1", to equal the diameter of the inlet/outlet of the bypass valve.

You don't even really need to drill/tap the bung. You could just use an unthreaded, ~1-1.5" long section of ~1" diameter pipe, shove it into a hole you've drilled that's ever so slightly larger than 1", and JB weld, MIG/TIG weld, etc. I had my buddy TIG weld the one I did on my parents' car, but it could've easily been just JB welded.

Edit: Braineack beat me to it! Don't make it difficult, just do it!
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Old 07-05-2006, 04:27 PM   #38
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Thanks guys!

Jay
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Old 07-05-2006, 06:26 PM   #39
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Old 07-05-2006, 09:59 PM   #40
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So this bov attachment:
http://www.jgstools.com/turbo/oav.html
Is basically an add on to an existing recirculating bypass valve? It looks like it comes with a hose and clamps so you can attach it to the other end of the Bosch valve so that it vents to the atmosphere?
Really, is the only problem with the VTA that it leaks and causes rough idles, stalling, and lean conditions while crusing? Because if so, this seems to be a nice peice from that will not leak and not cause those problems... you could get the Bosch and this attachment for ~$65 - alot less than any high quality VTA that won't leak...
-Ryan

Last edited by ThePass; 07-05-2006 at 10:09 PM.
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