Oil catch can Install question, about crankcase vent port

Hi, another oil catch can question, I'm installing 2 oil catch can on my 08 Legacy GT, I have installed the one that connect to block head to one catch can and the other one to catch the oil from pcv valves, I have installed it from the pcv valve to intake manifold, but on some diagram I see that you need to start one line from crankcase vent port. I don't understand the necessity to route a line from this vent to catch can. It seem that line goes to the engine block if I follow it. See my picture in attachment, see the red circle. What if I let this line there intact ?

Thanks

You may want to PM someone like "m sprank" he has a lot of knowledge. Ask him.

I'm guessing you want the pressure in the cans... ?

I have read this article http://www.radiumauto.com/Blog/Post/New-Product-Release-Subaru-AOS-and-Oil-Catch-Cans-103

What I understand now that is when the car is under load or high boot teh pcv valve close and the air and oil is send direct to the intake, I follow the diagram and clos the ose to the intake and routed it to the no 2 catch can. I'm not sur if i,m right.

I can understand the desire to not have oil dilute the fuel charge.

Not sure if it helps, but I had one of these put on my 05 years ago.

https://www.google.com/search?q=sg+motorsports+aos&oq=SG+motorsports+&aqs=chrome.5.69i57j0l5.16373j0j8&sourceid=chrome&ie=UTF-8

NASIOC may have some info that will you.

I have read this article http://www.radiumauto.com/Blog/Post/New-Product-Release-Subaru-AOS-and-Oil-Catch-Cans-103

 

What I understand now that is when the car is under load or high boot teh pcv valve close and the air and oil is send direct to the intake, I follow the diagram and clos the ose to the intake and routed it to the no 2 catch can. I'm not sur if i,m right.

This is correct. The line in question vents the crankcase while under boost.

I dont like how Radium and your diagram mix it with the head vents though, because those should be flowing air into the block under lower loads. Thus you're contaminating the clean air flowing into the heads reducing the systems effectiveness in clearing out bad gasses.

On my dual can setup I actually run the crank (non-pcv) vent and heads to separate cans. Then the PCV valve is hooked up like factory. This allows water and fuel to be burned off under vacuum, but stops oil vapor for clogging up the intercooler and throttle body.

This is correct. The line in question vents the crankcase while under boost.

 

I dont like how Radium and your diagram mix it with the head vents though, because those should be flowing air into the block under lower loads. Thus you're contaminating the clean air flowing into the heads reducing the systems effectiveness in clearing out bad gasses..

Thanks for the advice, I install 2 catch can. One from after pcv to the can and come back to intake manifold. Then a other that come from crankcase, no pcv and I joint this to 2 t from cylinder head to a can and come back to air intake. I cap the other hose from air intake. What do you think about it? It seem's like your setup?

On my dual can setup I actually run the crank (non-pcv) vent and heads to separate cans. Then the PCV valve is hooked up like factory. This allows water and fuel to be burned off under vacuum, but stops oil vapor for clogging up the intercooler and throttle body.