This seems like a pretty logical setup. I assume that under vacuum, you have the checkvalve on the turbo inlet prevent a vacuum leak back to the manifold. And under boost, the intake manifold side check valve closes?

Now, I believe the LS6 valley cover has an effective 0.100" diameter fixed orifice. Do you worry about making more blowby gasses than can effectively pass through this orifice? I suppose the breather on the driver side cover could always assist if the crank pressure got higher than atmospheric. You ever smell crank case gasses after a WOT run?

 

Can we get a picture of this setup? I see quite a few botched pictures, but if the setup works, let's document it with part numbers if you've got them for other users.

 

I think clean air in/out of opposite ends of the engine always good idea. but im also perfectly fine with in at valley plate and out at valve cover(s) since the valley is a little better protected and baffled.

 

But we're agreeing on the consensus is that the .100" effective diameter opening in the valley cover is just flat out not enough. Are we thinking one breather on a valve cover, the other valve cover and valley cover to catch can with lines to stock PCV location and possibly inlet/filter of compressor?

 

you cant hook the intake manifold vac direct up to the crankcase, it will pull it into a vac, carry even more oil, throw your idle way off, or all of the above.

so considering that we must have this regulation point, and that for a boosted app we also must keep boost from back feeding to the crankcase

in factory form the path of least resistance for blowby would be blown backwards out the fresh air port.. bummer because now you are consuming all the blowby your engine makes vs. clean air right when you would love clean air the most.
-also as hp increase so does this flow, and the more flow you will eventually whip up proportionately more oil with it.

so to control the situation from both ends is best, and truly manage the airflow for the new situation, sometimes better than stock.

 

Correct. When under vacuum, the check valve on the compressor inlet closes and the one to the intake manifold opens. then when you go into positive gauge pressure, the one off the intake manifold shuts, and the one on the compressor housing inlet opens as the incoming air creates a pressure drop and pulls the crankcase fumes from the catch can.

I might start pulling from the passenger valve cover into the catch can instead, like I do on my other non LS based V-configured turbo builds. I have just been using the valley cover to keep from having to drag the fumes up through the valvetrain on the passenger head if I can avoid it. But I catch alot more on my other setups than I do on the turbo LS1...I will either switch it or add an additional line to the passenger valve cover and "Tee" it into the catch can inlet line. I like to pull from back/front corner of 1 valve cover, to opposite back/front corner of the other valve cover to try and "flush" as much of the blowby, aerated oil, fuel that has made it into the crankcase and vaporized water hanging out down there.

On my ecoboost, I collect about a GALLON of nasty fuel, water, and oil with the setup I built between every 5k mile oil change....in that order of highest to lowest concentration % of total volume captured.

 

MM is correct on idle being thrown off changing the PCV system.
I switched from the LS-6 valley source to using a valve cover due to oil pickup-after that I had trouble starting, running until it warmed up.
I blamed it on something else I did at the time, so my thinking was thrown off-I have the Holley HP running the engine, and now the engine was getting less air at idle, causing a rich cond.-I noticed the IAC was high, trying to compensate, so simply opening the throttle blade, getting the IAC to a lower #, then a throttle reset cured it-I was surprised it made that much diff

 

a 'tee' connecting clean side to dirty side will completely defeat PCV function

 

Here's a real world test. I have an 02 SS (see signature for mods) and run a MM PCV Catch Can. I have the can mounted down low next to the air dam for easy access draining. I utilized the factory plastic PCV lines running to both valve covers and then tied into the port behind the throttle body for vacuum, and the vent runs to the turbo inlet filter using 3/8 silicon vacuum line throughout. I've had it this way for two years now, I removed the throttle body elbow a couple weeks ago and the inside of my throttle body was totally clean and dry. I also don't experience any smoking out of the turbo or any other crank case ventilation issues. Very happy with this unit, just buy one and be done with it, you won't regret it. Cheers.

 

Curious if under boost, a line run to the inlet filter has suction-seems if there were any amount of restriction, it would draw air thru that line-I guess that would help relieve pressure?

 

normal pcv path uses this location as a source. that is why it is after the mass air meter. so all engine air is measured by the mass air sensor first, some continues to the throttle body and some is borrowed for use by pcv system, enters the crankcase, leaves crankcase at another point (with fumes, contaminants, and oil) all powered by and returned to the intake manifold vacuum.

in stock form when there is no manifold vacuum accumulating fumes can and do move in both directions, and in boost obviously the only way out is back out this fresh air tube... in stock form..