scooter3

Based on a lot of recommendations I picked up the Hot Pink spring for my Tial BOV since the spring that was in it seemed to be too stiff. Now that I have it in it is absolutly annoying. Maybe it is my age, but all you hear is a constant whoosh at normal driving and when I give it heavy throttle, not WOT it will close and then open up when I let off the gas and whoosh again. I know I have asked this question many times, but is this normal? Tial has other springs that have a 6 and 8 PSI rating. I know it is all based on vacuum at idle, but I have no idea what that is since I do not have a boost gauge. Any thought?

Kerns

That is normal and how it is supposed to sound. If you don't like the sound you will need a different BOV. To elaborate, the BoV will close when you give it more then around 50% throttle allowing you to build boost. Otherwise it stays open so you motor wont ever see boost unless you are 50%+ boost. The woosh sound is simply the air escaping from the blow off valve.

scooter3

That is what I figured and what most have stated. Again it may be my age and I only took the car around the block to see how it sounded. I will give it a few days and maybe I will get used to it. Thanks for the info.

Soldier GT

I love how mines sound.. Nothing like getting on her, passing a car and letting that BOV sound off..

Harryman2002

You'll learn to like it, I thought mine was a bit excessive at first but it's fun to play around with it.

Soldier GT

^^sounds like a man that lives on the wild side!!!!!!!!!!!!!

amoosenamedhank

Huh? You realize that a BOV does nothing for the process of building boost. I think you are confusing a BOV with a waste gate.

In the resting position the BOV is closed, otherwise you would be allowing metered air to escape the system.... not to mention you'd have one hell of a boost leak. Under positive manifold pressure the BOV will remain closed but when the engine goes into vacuum the BOV will open to release the excess pressure.

Kerns

Negative ghost rider. The BOV is before the MAF. The air that you are allowing to escape is never seen by the MAF. The BOV will close when you go beyond around 50% throttle otherwise it will stay open. At least the TIAL does. There are some BOV's that will stay closed and will only open after you have let off throttle from boost and will allow the excess air to escape. Mine, Soldiers, 0949er, and Scooter3's all stay open otherwise.

amoosenamedhank

You may be getting away with it because you're using a blow through setup but I assure you that is incorrect. The valve should absolutely be closed during idle.

What do you think the purpose of the spring is for? If the valve did work the way you are purposing... there would be no need for a spring. I have no idea where you getting this 50% throttle business either. The diaphragm doesn't close at 50% throttle position, it's based off when the engine is in vacuum/positive manifold pressure.

You're suppose to pick the appropriate sized spring to hold the diaphragm closed during idle. That's why on tial's website there is a chart listing which spring should be used in which -psi or ig/HG situation.

http://www.tialmedia.com/documents/w3_tial_bov50_sp.pdf

Edit: I'm trying to think of ways to better explain this to you. Basically what you have is an unmonitored vacuum leak. I'm not sure why this doesn't register with you. You have a large hole (open BOV) in your system.

Here's how it should work:
Air enters your system through the air filter, it goes through the supercharger into the hot pipe. The air passes by BOV because it is being held shut by the spring. The air the passes through the intercooler into the cold pipe (where your MAF measures the airflow entering the engine) and to the throttle body.

Here's where you're going wrong. In your situation, your air is entering through air filter, through the supercharger and onto the hot pipe where it's immediately being released from the system by the BOV. This is called a vacuum leak. You car remains running because the MAF has yet to see this air yet, so it doesn't recognize the leak.

Blk003GT

My tial stays closed until I build boost and let off the throttle and go into vacum at which point its a psshhh and back closed again. All a bov basically does is prevent compressor surge.


However on some s/c cars when they get off the throttle there is a continuous purge of air until throttle is applied again. Dont know why its differnt.

Im speaking on personal knowledge however im turboed and not s/c