Oil everywhere under WOT
Well I'll ask you a simple question instead.
How on earth do you expect a system at 10, 20, 30psi to pull vacuum from a crankcase ?
No restrictor or valve will ever allow that because the pressure difference is always in the wrong direction.
Your drawing will never pull anything from the crankcase under boost. It is physically impossible.
How on earth do you expect a system at 10, 20, 30psi to pull vacuum from a crankcase ?
No restrictor or valve will ever allow that because the pressure difference is always in the wrong direction.
Your drawing will never pull anything from the crankcase under boost. It is physically impossible.
Last edited by kingtal0n; Oct 16, 2015 at 10:52 AM.
There are other posted pictures of PCV route, and I have added to this discussion with an identical routing that is just easier to understand. In this way, we are discussing PCV and its effects on boosted engines, and how to achieve maximum performance (as crankcase ventilation directly influences power output as well as emissions and cleaner oil) on any engine with a turbocharger. i.e. this discussion is highly relevant and I have gone to great lengths to simplify these scenarios to facilitate understanding by those without backgrounds in chemistry/physics.
Launching!
Joined: May 2013
Posts: 270
Likes: 30
From: Detroit
Well sir, I would ask you look at the picture I have posted again. It is an OEM diagram that I have simply copied in my own way. If you trace the route from the turbocharger inlet (where there will never be any pressure above atmospheric unless the turbo is in surge) you will notice that it connects directly the crankcase. Indeed, this is your "engine vacuum" during boost, that is, the turbo inlet produces a vacuum signal (very weak behind a good air filter, but nevertheless, present) and this vacuum signal draws air from the crank case during boost, which would have been near atmospheric pressure on an engine with good rings and proper PCV. In this way, all OEM manufacturers are able to provide PCV action during boost using their turbocharger's as "vacuum pumps" as you put it earlier.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
There will not be vacuum in the crankcase, but the OEM method does allow dirty air/oil/crankcase smellies into the inlet tract. Not something you'd ever want on a performance engine so it is a bad way to do it. But it works for OEM, they dont care about a little oil ingress and they must run an entirely closed system.
IF you can achieve proper oil/air separation, then yes you could vent the crankcase back into the air inlet of the turbo on a performance setup.
There are other posted pictures of PCV route, and I have added to this discussion with an identical routing that is just easier to understand. In this way, we are discussing PCV and its effects on boosted engines, and how to achieve maximum performance (as crankcase ventilation directly influences power output as well as emissions and cleaner oil) on any engine with a turbocharger. i.e. this discussion is highly relevant and I have gone to great lengths to simplify these scenarios to facilitate understanding by those without backgrounds in chemistry/physics.
This is an interesting perspective I would expand on. I would ask first to define a performance setup. This term has varied definition. I will therefore ask a question: Is a vehicle that weighs 3000lbs and runs 12 second quarter miles with a decent tire (perhaps 12.3 @ 116mph) a performance setup? If so, then I have just described a Nissan Silvia 2002 factory vehicle, with no performance modifications (besides the tire) and it indeed does achieve proper oil/air separation due to it's OEM valve cover baffle (as should all OEM engines with proper OEM baffles regardless of "performance orientation" although plenty do not), and there is indeed a vacuum in the crank case during boost when measured compared to atmospheric.
All of this is true and yet- this is the factory method, not necessarily a "performance" method, since the car has no modifications and simply falls into our category of "performance setup" due to it's quarter mile performance. This is how the engine is expected to run for 200,000+ miles.
Thread Starter
Joined: Jul 2005
Posts: 350
Likes: 2
From: Mountain Home, ID on My way to Korea!
MM was 100% correct as I had my setup N/A and not boosted. I relocated the hose from my passenger head to the the throttle body to the inlet of my turbo and I have completely resolved my oiling issues. I guess I get too excited and didn't just read all of the instructions. Simple mistake and 100% my fault. I've put about 100 miles and not a drop of oil. Thank you to the members of this forum for taking me from murdering mad to delightfully pleasant!
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