Thread: Crank Case Ventilation fully explained. (Turbocharged edition.)

Ben,
Why hasn't this option been discussed?


From what I would think, this scenario would largely only impact the system under WOT conditions. Since the WOT conditions do not pull much (if any) vacuum on the crankcase to help seal the rings, venting to air would not be any different pressure wise as venting to intake. The only negative is the whole EPA emissions thing. One could even put a catch can on the PCV hose line along with this to further lessen the level of oil in the intake.

Anything open defeats the purpose and if you run one port open, you may as well run them all open. The best scenario is to buy two legitimate catch cans like the saikou michi or Radium Engineering options that have oil separators and baffles in them run. You run one on the PCV system and one on the crank case system. This way you can run both lines back to the motor (intake pipe and intake manifold). This allows you to pull vacuum all the time. You need a one way valve capable of holding boost pressures on the PCV system to stop boost air from going into the PCV catch can and PCV valve. These valves can be built by you or purchased (such as the RIPP 30psi PCV).

Brent

Saikou Michi OCC Explanation

There is a reason these cans work unlike 95% of the cans on the market. They are designed to move the oil vapors down, then draw the air upwards through the separators and properly remove oil from the vapors. Using these on both sides along with a one way valve on the PCV system between the oil catch can and the intake manifold will get you the best overall results.

Brent

Thanks for the reply. I understand the sentiment to some extent, but if the catch can on that side mostly experiences flow during WOT which is a non-vacuum condition, what are the negatives (other than environmental) that the engine would experience? If there is no vacuum, then ring seal in not improved, so there is no loss by venting to air?

Thanks

I am sorry, but on a turbo setup WOT is still a vacuum condition because the hose goes to the intake pipe which is sucking IN air. So your whole idea on the premise that this is a non-vacuum condition is wrong.

Brent

Gotcha, I read this whole thread as well as the N/A thread and it was never stated as such or I glossed over it. I thought that it was likely for vacuum to be achieved through the intake (in much the same manner as plumbing to the exhaust would) but figured that the level of vacuum must have been so low that it was essentially 0.

Thanks for the clarification.

Not a problem man, glad I could clear it up. The issue that we run into on the forum is that very few people take the time to actually test different setups and see how they perform and you just need to keep posting like you did and the answers will eventually come through.

Brent

The last example had the image missing. I've restored it.

This routing is causing some discussion, so we can talk here.
@blo0d
@2_Liter_Turbo



And here's blo0d's theory and question.

@blo0d, my gut tells me this setup won't work the way you're expecting, and in general I am dubious about the design. However the owner (2_Liter_Turbo) has said he tried just the exhaust scavenging but wasn't getting amazing results so he added on the addition port on the intake and is now having good results, so take what I have to say with a grain of salt.

You have three pressure areas in this setup. The valve cover pressure, the exhaust scavenge pressure, and the intake pressure. Which ever pressure is lowest, will be the direction air travels. I would bet that is the exhaust area most of the time we care about. This means air from the valve cover AND air from the intake will be drawn to the exhaust. Any air drawn from the intake to the exhaust is taking up room that blow-by air should be taking up. Not only that, but the intake port allows for a lot of unrestricted, free flowing air which is more likely to head down the exhaust than the stuff in the valve cover (assuming the valve cover is properly restricted on the PCV side and/or the WOT side).

All in all it is not filling me with tons of confidence. It could be way worse though.

The improvement 2_Liter_Turbo saw is making me think that the intake route must have lower pressure than the exhaust route, in which case he could just get rid of the exhaust route altogether and have identical function with less complexity.