2nd to last paragraph: This is a very good point and something I had not considered. When the pcv line is sucking in air/crankcase gases a lot of it may be coming from the turbo inlet and not the crankcase (at least some if it) - kind of like taking a pull from pipe without having your finger on the carb :lol:. This must be why the line going from the plastic pcv "y" fitting to the turbo inlet is restricted to about the size of the end of a chop stick at the fitting. I would still think that most (or more) of the air it's pulling in would be from the crankcase. I say this because the pcv valve sits directly on top of the crankcase fitting with a 1/2-3/4" ID line going right to the the pcv valve, unobstructed. The line going to the turbo inlet sits above the pcv valve and is restricted to the size of the end of a chop stick. It really makes me wonder why they chose a setup like this; I wish I was more knowledgeable on the subject.First of all, thanks for posting those diagrams and starting an interesting discussion. What follows isn't just aimed at you specifically, but at everyone following this thread...
I don't "get" the diagram above. Is there positive pressure in the crankcase the intake manifold is in vacuum?
If there is, then there's really no need for the PCV anyway. I mean we might as well put a cork where the PCV is... The crankcase can just ventilate itself into the turbo inlet due to the crankcase pressure and the (however mild) inlet vacuum, as shown in the 'under boost' diagram.
If there is not any positive pressure in the crankcase in cruise, then I don't see why the intake manifold vacuum pulls much air from the crankcase. I understand the vacuum created by the intake manifold, but the path of least resistance is to just pull air in from the turbo inlet. It seems to me that without positive crankcase pressure, the line that runs from the PCV tee to the crankcase is basically just stagnant, with the PCV pulling lots of fresh air over the top of the tee, and perhaps pulling a minute amount of air from the crankcase just from venturi effect at the tee.
Why does air flow from the intake into the heads? Where does that air go? I don't see why the air in the head breather lines doesn't just stagnate as well. If anything I'd expect it to flow back to the turbo inlet, due to the mild vacuum there and perhaps mild crankcase pressure due to blow-by. Does something beween the crankcase and heads pump air from the heads into the crankcase, or even just act like a one-way valve?