Recirc vs. Atmos Question (Education needed)

[KamaSupra]

I have a stock 7MGTE. I am so ubernoob its not even funny. I have a decent technical grasp (but I was raised on pushrod V8s and this is my first turbo)

Anyway, I recently bought a brand new Turbosmart Vee Port II because I got a good deal on it. Its supposed to be universal. Since I bought it, I've been informed by some other Supra owners, that venting to atmos will be a problem for me. The car is auto (I think that actually matters here, due to shift speed)

So, my question is this, what is going to happen if I install this BOV? Should I go ahead with it, or just sell it to some Subaru owner?

 

[RazoE]

the reason Supras stall with atmospheric BOV's is because air coming in is measured by the AFM, and fuel is added accordingly. When you vent to the atmosphere, the car still thinks the air is there (OEM is recirculated), so all that extra fuel is still there, but there's no air to burn it, so you run super rich and bog, or stall..

it's worse in a 5 speed car, as we shift into neutral when coming to a stop or slowing down, so RPMs drop right away. Autos hold boost between shifts and rpms drop slower, so they don't stall or bog as often.

I don't know about an auto Supra, but in my 5 speed, if i leave it in gear and engine brake until I get to around 1000 rpms, I won't stall (I have since reciruclated my HKS bov)

results vary though, my friend's 5 speed can let off 11 psi of pressure and not stall, and he has the exact same mods I do..

 

[CyFi6]

The problem with venting to atmosphere is that you might experience a stalling or studdering when coming back to idle or a popping when you let off/re-enter the throttle. The ECU (TCCS) measures the amount of air coming into the engine at the afm, before the turbo, and when you let off the throttle, an atmosphere venting BOV lets the air out from the intake right before the throttle plate. Air that is leaving the intake pipe is air that the computer has already measured, and is expecting to go into the engine, so therefore it provides fuel for the engine. Now you have a case of fuel being delivered to the engine, but not air, so it runs rich for that amount of time the valve is venting.
Granted a lot of people have atmosphere venting BOV's with an AFM, but it is not the proper way to do it and will likely cause driveability problems. Best bet is to keep it recirculated. When you recirculate it, the air being dumped goes back into the system, after the AFM, therefore any air that has been measured stays in the system.

A lot of people go with the Bosch style bypass valve, but I tried it and it made a very annoying "hooting" sound at around 0psi. I am actually selling a Turbosmart bypass valve right now, I used it with great results.
http://www.supramania.com/forums/sh...mpact-DualPort-Bypass-Blow-Off-Valve-like-new

 

[KamaSupra]

Looks good. You ship to Canada? I can probably sell mine to cover the cost of yours and then we'll both be happy.