MR2 Bypass valve install, recirculated. A couple questions..

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Postby Gary » Thu Dec 20, 2007 7:09 pm

White plastic piece = VTV (vacuum transfer valve)
It is NOT a regular check valve.
It costs about $35 from Toyota.

Here is how you hook it up:

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Postby maxaud » Thu Dec 20, 2007 7:34 pm

I was waiting for Gary to chime in with a MSP Illistration
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Postby BriinumsBo » Thu Dec 20, 2007 7:37 pm

Vacuum Transfer Valve? :shock:
thanks for the links, ill try..
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Postby phattyduck » Thu Dec 20, 2007 8:21 pm

BriinumsBo wrote:Vacuum Transfer Valve? :shock:
thanks for the links, ill try..
It is a very specific restrictor that allows the dual chamber stock bypass valve to open for a specific amount of for shifts and throttle lifts and remain closed for cruising, accelleration and idle. Without the VTV, the valve does not work at all.

HKS BOVs use the same style design, but have the vavle internal so it requires only one external vacuum line.

-Charlie
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'99 4Runner SR5 4WD 5VZ-FE
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Postby lumbercis » Thu Dec 20, 2007 8:31 pm

I saw somone who had T'd both vacuum lines together and then ran the one line to a vacuum source. Would this cause the BPV to not work at all or would it only work off one "chamber."

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Postby gpmarzan » Thu Dec 20, 2007 10:29 pm

lumbercis wrote:I saw somone who had T'd both vacuum lines together and then ran the one line to a vacuum source. Would this cause the BPV to not work at all or would it only work off one "chamber."

J.


I sure hope that I can run my car w/out that vtv. $35 for that lil thing is just crazy.
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Postby gpmarzan » Thu Dec 20, 2007 11:25 pm

anyone know the part number for the vtv? is it the same as a one way check valve?
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Postby 88st165 » Thu Dec 20, 2007 11:29 pm

its almost like a check valve but it doesnt stop flow one way, it limits it.... (full flow one way->)(<-limited flow the other)

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Postby wizzards581 » Fri Dec 21, 2007 2:38 am

gpmarzan wrote:
lumbercis wrote:I saw somone who had T'd both vacuum lines together and then ran the one line to a vacuum source. Would this cause the BPV to not work at all or would it only work off one "chamber."

J.


I sure hope that I can run my car w/out that vtv. $35 for that lil thing is just crazy.


the bpv will not work correctly without the vtv.
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Postby gpmarzan » Fri Dec 21, 2007 2:55 am

This is what I read about the vtv:

"The large round area at the top is a diaphragm. The area on the top of the diaphragm is larger than the area under the diaphragm. Now note there is hose directly from the manifold to the top (large area) of the diaphragm, and another hose tee's off that goes through a check valve to the underside (small area) of the diaphragm. When there is pressure (boost) in the manifold, there is equal pressure on both sides of the diaphragm, but since force=pressureXarea, the greater force on the top holds the valve closed. In fact, the higher the boost, the more tightly the valve is held closed. Now as soon as you lift, and pressure starts to drop in the manifold, air immediately escapes from the top of the diaphragm, but the check valve restricts it from escaping on the bottom, and the pressure on the bottom quickly exceeds the pressure on the top, and the valve snaps open. If you reverse or eliminate the check valve (VTV) then you can't trap pressure under the diaphragm, and the valve cannot respond as quickly.
Conversely, the check valve insures that when there is a vacuum condition, more vacuum will be applied to the top of the diaphragm, and it will open and be in bypass mode.
The diaphragm section of the valve is connected to a spool in the main section of the valve. That spool opens and closes the connection between the crossover pipe and the intake air pipe. When the diaphragm is pushed (or pulled) to the top, the valve is open, and when it is pushed to the bottom, it is held closed.
There is just a light spring on the spool in the main body. Its only function is to return the valve to its normally closed condition when the engine is not running."

from that, it says that the check valve "insures that when there is a vacuum condition, more vacuum will be applied to the top of the diaphragm" which explains the limited flow in one direction. My question is, what if there is no flow there (regular one way check valve)? It would still put more vac on the top diaphragm as it wont have vac on the other port, right? same thing will happen when under boost as pressure will go through the 2 ports. Maybe im missing something here :shrug:
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Postby phattyduck » Fri Dec 21, 2007 6:11 pm

gpmarzan wrote:from that, it says that the check valve "insures that when there is a vacuum condition, more vacuum will be applied to the top of the diaphragm" which explains the limited flow in one direction. My question is, what if there is no flow there (regular one way check valve)? It would still put more vac on the top diaphragm as it wont have vac on the other port, right? same thing will happen when under boost as pressure will go through the 2 ports. Maybe im missing something here :shrug:
That's an awesome explaination of the stock BPV!

The small thing you are missing: You want the valve to be closed at idle and after a short time under throttle lift (decel in gear, etc). This is why the VTV allows some air back and is not a full one-way valve.

-Charlie
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'99 4Runner SR5 4WD 5VZ-FE
Previous: '88 Camry LE Alltrac 3S-GE BEAMS, '90 Camry 3S-GTE, '90 Camry DX
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Postby gpmarzan » Fri Jan 18, 2008 10:39 pm

This is what came with my st205 intercooler. Stock?

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Postby Gary » Sat Jan 19, 2008 6:45 am

^^^
Yes.
On ST205, the valve actually mounts on the air filter box.
There is a hose coming from the lower right corner of the IC to the valve.
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Postby maxaud » Wed Aug 06, 2008 1:44 pm

This post may be good in the "how to" section
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just musing...

Postby grip addict » Fri Aug 08, 2008 6:47 am

i'm running a recirc'ed ssqv. i'll try to get pics up. its a little ghetto for now, but i want to get a bigger flange (Read-correct size) welded onto my intake pipe. the car definately drives better, doesn't backfire as much, on/off boost is much more transparent.
now the question of the day-
i wonder if the 18 psi that i'm moving would be enough to spool the turbo momentarily? or at least keep it spooled. if you plumbed the line to the exhaust man and had it push air directly onto the turbo blades, i wonder how fast they would spin. you'd probably have to use a check valve or something...
i need to warn everyone-
ATSAaron wrote:You specifically told Matt that "some kid dumped sand into my motor."

don't let some kid dump sand into your motor.
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