Wow alot of great info, I have a few ideas to pick from now LOL!

 

This is what I'm running now (as of last night):
-During Cruising the intake draws vacuum on rear ports.
-During Boost the turbo draws vacuum from the intake side (tapped the filter pipe of the STS)
-Check valve #1 prevents the intake from pulling vacuum out of the catch can.
-Check valve #2 prevents boost from entering crankcase
-Front port on pass valve cover is venting to atmosphere through a 3" filter at all times

Issues: I think there needs to be another catch can before the line running to the intake because the PCV is the only thing catching oil before it reaches the intake manifold during vacuum.

If I could rework this, I would run a 3/8" line off each rear port going to their own catch cans. Then the outlet port of each catch can would "T" togethor and run into the intake for vac. The pass front port would still vent to atmosphere. During cruising the #1 check valve would stay shut as the intake is pulling vacuum and that would prevent oil from getting into intake of turbo. Then under boost the turbo would pull vacuum, the #2 check valve would shut and the oil would still be caught by the catch cans before running down the lines going to the turbo because they are installed in-line right off the valve covers.

Heres a pic of how it is now:

 

The car doesn't consume any oil at all .

It's only a slight whistle and only on idle ,Under load or even when I put my finger over it it goes away .

I'm going to fit a small filter on it and see what happens .

 

Why would you think that would supply air into the crankcase, as that area is in partial vacuum (out of boost)...just like anywhere on the intake side. Again, what is the rationale for introducing atmospheric air into the crankcase. We want some vacuum for better ring seal. Am I missing something here?

 

Try this, pull vacuum on your crankcase with no way to let air in. When your engine pulls a seal or gasket inside or sucks your Rear Main Seal in, that should provide the answer you where looking for. And even if that line at the throttle body is pulling a small vacuum from the venturi effect, the large vacuum of the pcv system will pull harder.

 

Javenger I think now that you put the second check valve there on the line to the turbo inlet, you've got the right set up. When the PCV stops pulling vacuum the turbo inlet starts pulling for you.

 

Pull IN the rear main seal? I have never heard of such a thing happening! So what happens w/ folks running the old belt driven vacuum pump? Are they adding air into the crankcase? Odd...just never heard of this being done. Do you know why the Krank Vent folks explicitly say NOT to vent to atmosphere (but actually want you to use a valve that allows one-way flow out of the crankcase, not in).

I appreciate the education...that's why I've been following this thread.

 

Here's some info from one of my old auto fundamentals books

 

Your talking about the setup where it vents from the front pass port? Or my older drawing?

 

just by browsing the above pictures; don' tdo it that way

if the catch can is not between the engine and the intake, then it cannot catch anything before it goes into the intake (oil)

 

Thanks for the add'l info...makes sense. So NOT having an original PCV valve in there is NOT a good thing. Mine is long since gone, having been tossed when I first adapted the STS setup for my GTO. Now with the GenTT twins, I need a better approach than the STS used (which had no valve, just a solenoid to prevent boost from flowing into the crankcase). The factory valve is obviously going to be important as well as the check valves. I hadn't realized the issue of pulling too much in at high vacuum times (I am picturing a downshift through a turn w/ HUGE vacuum, then stomping it open on exit...lots of crud will have been drawn in).

Is there a decent (and cheap ) "universal" pcv valve that will work with with the McMaster check valves?

Again, thanks for helping me to better grasp this. Lots to think about.

 

Yep! I thought that was odd as well. I would think the catchcan should always be located next to the crankcase, and then the port to atmosphere OR intake depending on intake pressure.

 

Second that.......

Yeah, it's just a vacuum canister!!

 

I see there is a difference, in trying to keep oil out of the intake, and keeping the stock pcv system working. I have never had any issue pulling too much oil into the intake. What I did was make my stock PCV system work while not under boost and the vent to atmosphere while boosting. If you are having a oil into the intake problem then an actual oil seperator somewhere in the line to the intake manifld would make sence. It seems that there are 2 seperate ideas going on in the same thread.

 

I cannot speak for an LS1, but the LS2 clearly needs a catchcan as part of the PCV system. With the previous setup, I caught a lot of oil in the 'Husky' separator that I used. I have decided to upgrade to a better catchcan now.

In the drawing above, simply insert the catchcan between the two "T"s and all should be well. That way, the oil is separated from the air whether going into the intake or the turbo inlet...or to the outside air, if that's the case.

 

Yepp, I noticed that last night. Like you said, Im going to move it up between the "T" fittings and remove that 2nd check valve. I don't think its needed.

 

what do you guys think about breathers directly on the valve covers? Do they make a mess? Or are they fine with baffling?

 

I agree with so many of you here..... as the thread states..... what is the final conclusive way to go?

 

I'm gonna stick to the breathers, and call it done. Don't get any oil smell and not much residue. Eventually, maybe... next build at least it'll be front mount and I won't have to run a line to all the way to the back to the inlet side of the turbo.

 

my head hurts too lol