Why doesn't anyone run the exhaust side VC port to their turbo inlet? I run mine that way so as boost builds, the PCV shuts, then the turbo is pulling a vacuum on the crankcase. By running a fresh air breather isnt the crankcase just going to atmospheric pressure and not staying in vacuum? The purpose of keeping the case in vacuum is to help pull the rings towards the walls.

Not to mention that when running a fresh air inlet style filter or tank on the valve cover you are essentially creating a vacuum leak at idle.

IMO the best option is to run two sealed cans. One on the intake side, the other on the VC to inlet side. This will keep moisture/oil trapped in the cans while preventing vacuum leaks.

Another option is the down draft style. Run a pipe from your exhaust/down pipe at an angle and a hose to your VC inlet. The exhaust will pull a vacuum if done properly but can cause some slight smoking and failing emissions.

 

I assume cause you want your turbo impeller clean. I would not want oil droplets hitting impeller blades at 150k rpm

 

Of course. Thus the purpose of the second sealed can between the VC and turbo inlet.

 

No air / oil separator is 100% efficient.

And, not only do you not want oil mist hitting the compressor blades, you also don't want it getting into the intercooler, where it will condense into liquid and coat the inside of the tubes.

 

I agree. One option not considered is a vacuum pump. GM makes them for a lot of vehicles. Not to be confused with their Air pump which are for cold start emissions.

 

Yea, no one in this thread has mentioned vacuum pumps already. >.>

 

Like nearly every single answer/comment on this website: it depends.

OEM (MSM) runs a type of catch can (ish) and drains the fluid back into the oil pan and returns that "cleaned" air back into line just before the MAF.

But in the case of higher horsepower (=more blowby) builds, you'll be sucking that poorly filtered air back into the turbo and everything else. Not saying it's impossible to clean it all out. But you'd need a really good catch can or maybe more. Twice now (different setups) I've had issues with blowing loads of crap into my intake. Until I can make a bullet proof catch can, I'm not going that path again.

Yes it helps to pull a little vacuum on the crankcase, but isn't anywhere near enough to make a difference in power. From what I've read, you need 12-14 inches of vacuum (a lot) to generate more power, but to truly take advantage of this pressure differential, you'd need to install thinner rings to reduce friction losses.

 

Would a check valve between the intake and catch can help, such that air can only be under vacuum from the intake? And no oil vapor being drawn into the intake tract.

 

That would be a disaster. As soon as you produced more blow by pressure than intake vacuum, you'd close off the valve and blow every seal in your engine.

 

Confused on the catch can setup for N/A track only conditions. Is the preferred option is to disconnect /block PCV and intake and run crankcase to can and back to intake ? Or is it better to have a dual setup like the Radium and run crankcase into one can and PCV into another can? I don't want my seals blown and since the car will be at WOT most of the time, Radium recommended that PCV could be deleted.

 

Delete and cap pcv valve. Run a 10an fitting on exhaust side of valve cover to catch can. Drill the port in valve cover and fill with copper scrubbers.

 

11:1 VVT motor. I run the stock setup on the intake side and a -06 hose from the exhaust side to a catch can. Small holes drilled in the covers and copper scrubbers. No issues with excessive oil in catch can.

 

when you say stock setup - PCV connected to IM?

Is the -6AN exhaust side welded or tapped for the fitting ? Is the drilling of the hole in the exhaust side baffles means enlarging the 1/4 hole that's already there to the middle baffle?

 

PCV attached to IM. Sorry, I was wrong on the exhaust size. Just a 5/16-3/8" (so -05-06) hose on the factory barb.

 

I was wondering if my car was worn beyond where catch cans and venting would help. It's an 01 with 160k 25k turboed. Check valve in the pvc line with a gtx pvc. The hot side has an 18' hose with a breather on it. It's blowing oil out the breather. About an ounce every hundred miles or so. Street use only. I had to stick the breather into a can, it was leaking oil all over. Compression test with Orilley's tester was 190-190-195-195. If it's rings I'll probably just replace engine when it gets too bad, but if it's in the head I have a somewhat fresh ported, CCed head I could use. What do you think. Do I try dual large vents or is it too late?

 

Joe, dual large vents will help, whether the extra blowby is caused by high boost or a tired engine. Either way there's an increased volume that needs to be relieved somewhere so it doesn't push oil out through the seals and gaskets.

 

Yes. Both holes in photo need to be enlarged.

 

i only have 1 hole port in the 99 VC

 

I haven’t modified your VC version but if that’s the port to the center chamber then that’s the one to enlarge. That small of a hole really adds an insignificant greater pressure relief if you make the IM side a -10AN + PCV delete VTA setup but I did it anyways like you are. I’m just thankful that my dipstick was loose enough to pop up rather than blow out seals before I did these VC mods.

 

I'm currently running both sides of my valve cover to a catch can which is vented to atmosphere. I am doing like 90% street driving and 10% track driving.

So is a bad idea and I should run cold side to intake using a pcv valve and catch and have only the exhaust side vta?