The Procharger valve is not a good example. A Procharger still moves a ton of air at idle since it's forced to spin. So the valve needs to be open at idle to let all of that air out. A turbo is not forced to spin at idle, and frankly, move much less air at idle than a Procharger (at least in my experiences with both), so having the BOV open at idle is not necessary.

It seems that having it open at idle would depend on whether or not your turbo is moving enough air to push air out the BOV instead of air getting sucked in through it. I agree that it probably doesn't matter if air is getting sucking in through it, but I would rather be safe than sorry. And from another thread, Tial recommends the BOV be closed at idle and cruise. Every youtube video I've seen of BOV's shows them closed at idle, and opening pretty easily after revving.

 

Tial also has many different springs so you can fine tune it. I believe the RPS valves only have 2.

The issue really isnt the turbo forcing it open, it is the engine drawing vacuum to open it.

 

Right now with the heavy spring in my RPS, it needs a couple PSI of pressure in the pipes to open the BOV, it wont even open at max vacuum. So I'm thinking of using the lighter spring and shimming it so it's closed at idle vacuum but open at above idle vacuum. This should make it far more responsive.

 

Make sure the valve isn't stuck or not moving smoothly. Mine wasn't the smoothest out of the box. They are chinese knockoffs afterall.

The valve should be opening at full vacuum even with the heavy spring. Mine did, but I put in the light spring just because I like the "woooosh" sound better

 

Obviously I was wrong, under vacuum it barely pulls it open it didn't seem like much. Had to double check. Vacuum is barely open, closed with zero vacuum and open after I rev it up . Sorry

 

I tried to shim the lighter spring, but it still was open at idle. I shimmed it about 1/4" which caused the spring to start binding when open, so there wasn't anymore shimming to be done. So I cut about 1.5 coils off the heavy spring. Works great now, closed at idle and cruise, but opens in vacuum 3-5 inHg greater than at idle. I also lubed it up so it open smoothly.

It's slightly more responsive, but I'm still getting a little bit of turbo flutter before the BOV opens. Is this normal? The only thing I can think of doing next is using a different/bigger port in my intake for the BOV, I'm using the AIR port on the back of the passenger side now. And shortening my line to the BOV, right now it goes to the passenger side fender, under the airbox, then over to the BOV right behind the radiator, about 8' long I'd guess.

At idle mine does suck in air through the BOV, if it's open.

 

If you have a low mounted bov like mine be careful if it opens under vacuum. I almost lost my motor this weekend because of mine. I was slowly driving through some deep water when my motor just died on me. I had stopped to go into reverse and it stalled. Tried to start it and the starter wouldn't turn it over. Got out and my exhaust tip was half out of the water and my intake filter was bone dry. So I tried it again, still wouldn't crank at all. Pulled the plumbing off the throttle body and water rolled out. Then it dawned on me that most of my intercooler was under water and my bov liked to crack open under large vacuum with the new motor.
Long story short I got the truck home pulled the mani and plugs and cleaned it all up. Motor fired up no problems with no piping hooked up. Took my bov off and water rolled out of the intercooler.

 

Damn.. you got lucky. I was thinking of mounting my new big red down low near the intercooler on my truck, will keep it up in the engine bay now that I think about it and hear your experience.

 

Dang! Close call! Mine is basically in front of the water pump pulley, fairly high up.

 

Mine is mounted to the cooler itself on the lower back side of the passenger side end tank. I would highly recommend up high if you can. It almost sucked real bad, not to mention the motor has been in the truck bearly a month. Had it not been for the truck idling so low when I went to go I to reverse i may have lost it.

Funny part is I watch several stock silverados drive right past me, even a ford f250 no problems at all.