From Jake N. of Tial, below. Sounds like air will always be exiting regardless of intake manifold... hoping to confirm with him shortly & will update
LINKY
Getting to know your TiAL BOV
First some commonly over looked facts about the unit:
- the spring ratings have nothing to do with boost
- the bov is a pull type valve - the vacuum sucks open the valve (which is why we have different spring settings for different vacuum levels)
- you need to put a washer on each side of the air fitting, they come with both on the inside so they don't fall out
- we have a -3psi spring for superchargers
the valve can be open or closed at idle depending on your air meter setup:
- if you are metering air BEFORE the BOV you will need to have the BOV shut at idle, unmetered air will be EXITING the bov and cause a rich condition because less air is entering the engine than previously recorded by the MAF sensor
- If you are metering air AFTER the bov it does not matter one way or another if the valve is open or closed at idle, since the air exiting the bov is before the air meter on the car you are going to get a correct mix of air fuel.
- if your air metering system is like this i would suggest a step lighter spring than the car is rated for, that will ensure you lightning quick response.
Is vacuum line size important?
Hell yes it is, if the line size is too small you will be restricting flow, which could cause problems. I've seen a LOT of evo owners get the required 1/4" ID line and attach it to the very small very restrictive connector right by the valve cover. the proper way to run the BOV is this: 1/4" ID reinforced line (brake line from autozone...it's cheap) running from the BOV ALL THE WAY to the intake manifold with NOTHING ELSE T'd into that line.
How do i know which spring i have?
It's on the box the unit came in
But i bought it used!
give me the SN on the top of the unit and I'll look it up
I hear you offer free bov spring swaps if my vacuum changes
Yes this is true, requirements are you must provide a picture of your unit and the SN from the top...some bozo's have tried to send us knockoff springs - we aren't stupid here guys, i can smell a fake from a mile away. you pay shipping, i turn the springs around the same day they come in. You must also include a note in the box with all of your contact info and what we are doing i deal with about 50-60 turbos/gates/bov's a week, when i open your box i need to know exactly what needs to be done, and will not ship back to the UPS store or the like.
