I'm running a Pettit CAI with the air pump disconnected (no cat). Lately, I've been wanting to remove that crappy plumbing between the CRV, ABV, air pump inlet, and filter.

On my old racecar, I vented both CRV and ABV to atmosphere, which seemed reasonable, since the car was only driven on the track every couple weeks or so. But for my street FD, I'm a bit more concerned about leaving CRV open. ABV obviously isn't an issue, since it only opens momentarily under significant pressure. CRV, on the other hand, is open at all times until the secondary comes online, and until pre-control starts spooling the secondary, there is no pressure behind it - that's my concern. If it's open and isn't venting pressure, debris can theoretically make its way in. Not to mention if there's even a miniscule leak at CCV, which could actually create suction in the secondary tract...

Anybody have any insight into this? I realize lots of people have vented both to atmosphere with no problems, probably for several years. Still, I'm leaning towards filtering CRV, and leaving ABV open. Any thoughts?

 

Why not filter them both and not worry?

Dave

 

Yep still get more air noise than if it into the Pettit tube but not quite as obnoxious as full open.

 

mine blows air just about at idle. but if it bugs you go ahead and put a filter on it /\ pep boys has them i think, kind of like the old school valve cover breathers

 

Yeah, I think I'd be more comfortable with them filtered. I guess I'll stop by Pep Boys and see what they have...

I'll be much happier when that plumbing crap is out of there - it really makes working anywhere around the filters a bitch!

 

not as obnoxious, yet you run two BOV's,

 

Dig Dug,

It is blowing when it's open. It's not blowing hard at idle, but it's blowing a little. It doesn't need to be filtered. However, I would route the exit hose down towards the ground in the engine to help reduce the noise as it's pretty annoying.

 

Not by choice I needed that pipe to use with the Greddy elbow and don't have one without the flange and BOV. My CRV is the one making all the noise most of the time (with the exception of track time.)

 

^remove the stocker and cap it with a 3/4" plug from Pboys...just an idea, remove some clutter.

 

So the secondary is always moving air, even at idle? I guess some exhaust flow always gets through the PC/TC valves?

Yeah, I remember the CRV noise from the racecar - it sounded sorta like a dump truck!

 

Well, the CRV is there to vent the access from spooling the secondary turbo befor it comes online. That way it just doesn't spool against a wall and overwork itself. So, it's venting whatever the turbo is producing; there's just not that much at idle.

 

I understand the purpose of the CRV, but my understanding is that precontrol doesn't open to allow exhaust flow to the secondary turbine until 3K, except at higher load on the primary, when PC cooperates with the wastegate to control primary boost. So in theory, at least at lower loads (including idle), the secondary shouldn't be spinning until that point, right?

If there is indeed flow through the secondary prior to 3K, I guess some exhaust flow must make it past the PC valve even when it's closed? Otherwise, I can't see why the secondary would even be spinning at all at idle...

 

Yes, and there is no vacuum before it starts spinning so the line isn't sucking anything in. Just venting it down toward the ground is fine. Actually, just leaving it open is fine, but annoying as you found out with the race car.

 

Good point, I think I'll just vent it - if there's never any vacuum, there's really no reason to filter it. I was being cautious because I didn't want to blindly make the assertion that there's never any vacuum in the secondary tract under any circumstances. I'm still a bit sketchy about the "under any circumstances" part, but then again, I never had any problems with the racecar, even with the occasional agricultural excursion through a cloud of grass and dirt.

To take the theoretical a little further, it seems like less restriction in the CRV output should improve pre-spool of the secondary, but now I've ventured into pure speculation...