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

I know we have nice detailed pics here, but I am still not understanding how the two vac lines coming off the BPV are hooked up. I have an mr2 BPV, but mine doesn't have the white plastic piece that the lower of the two lines (the short one) seems to hook into. Do I need it? Any way around using it?

Also, where are you guys hooking the topmost vac line to?

Thanks,
J.

BriinumsBo":31oiqkj3 said:

well i`ve spent 120% of my last 5 salaries on the car, 2400eur for engine rebuild (rings, bearings, gaskets), just because of overboosting/maybe detonation.. anyways i want to make sure my engine runs healthy

do you know any place where to get an MR2 bpv online? I doubt i can get any in my country.. there are maybe five MR2`s in the whole nation

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And exactly where are you based?

Latvia.. you shouldnt know

BriinumsBo":dktjqvuf said:

do you know any place where to get an MR2 bpv online? I doubt i can get any in my country.. there are maybe five MR2`s in the whole nation

Click to expand...

try the UK MR2 forums

http://www.imoc.co.uk/forums/viewforum.php?f=46

http://mr2oc.co.uk/ForumsPro/viewforum/f=87.html

http://www.tbdevelopments.com/forum/viewforum.php?f=18


hth

lumbercis":1ms9c5b6 said:

I know we have nice detailed pics here, but I am still not understanding how the two vac lines coming off the BPV are hooked up. I have an mr2 BPV, but mine doesn't have the white plastic piece that the lower of the two lines (the short one) seems to hook into. Do I need it? Any way around using it?

Also, where are you guys hooking the topmost vac line to?

Thanks,
J.

Click to expand...

The white piece is needed, after that it just T's into the other one and goes to the vacuum source.

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:

I was waiting for Gary to chime in with a MSP Illistration

Vacuum Transfer Valve? :shock:
thanks for the links, ill try..

BriinumsBo":1ffip4f3 said:

Vacuum Transfer Valve? :shock:
thanks for the links, ill try..

Click to expand...

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

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.

lumbercis":2qcs0d68 said:

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.

Click to expand...

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

anyone know the part number for the vtv? is it the same as a one way check valve?

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

pn:
90925-01059

gpmarzan":syotqz8p said:

lumbercis":syotqz8p said:

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.

Click to expand...

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

Click to expand...

the bpv will not work correctly without the vtv.

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:

gpmarzan":35yburhq said:

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:

Click to expand...

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

This is what came with my st205 intercooler. Stock?

^^^
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.

This post may be good in the "how to" section

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...