I have a stock longblock 4.6 2v with an old design (pre-2011) TurboSmart Raceport BOV about a foot and a half from the turbo before the intercooler. It is a blow thru setup and vents to the atmosphere. I see -20in/hg at idle and decel. Now should the BOV be open at idle or closed? I can't hear any air coming out of it and I swear it's closed while at idle and cruising. I rev it at idle and still doesn't open. They ONLY time I hear it is when I see positive pressure. It has worked flawlessly under load.

So is my setup fine or not? I read that Tial and TurboSmart said it doesn't matter if it is open at idle or not in a blow thru setup but prefers it to be closed.

Thank you TTF,

Scotty S.

 

Sometimes when you have a motor that can pull lots of vacuum, like you have, it will pull the bov open at idle. As long as you have the line hooked to the top I would think it to be working correctly.

 

Yes it is connected to the top and line is post t/b. I am 99% sure it's closed at idle and cruise.

 

I wouldn't worry about it if it not opening at idle is the only thing you are concerned about. Are you getting compressor surge when you lift with the turbo lit? Does it open when you free rev the engine?

 

I have heard surge maybe twice but nothing crazy. I mean it was like at .5 psi. I can hear the turbo whistle when climbing a hill and I dont hear the BOV or surge when I let off. No it doesn't lift when I rev it at idle. But I read it's ok if it doesn't. There isn't really any load. No surge either at that time