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I have found a way to completely upgrade the PCV system so that oil no longer will get sucked into your plenum or blown into the turbo intake pipe to circulate through your piping, intercoolers, and on into the plenum and get burned in the chambers. Here's how the stock system works:
The PCV system is designed to flow clean air through the crankcase of the engine so as to get rid of the blowby gases (mostly fuel) that can contaminate (breakdown) the oil. This is done by using the manifold vacuum as a scavenger (sucking) to draw clean air into the crankcase. The air enters into the crankcase through the intake valve covers. They are the two highrise pillars on the front of the covers and there are metal pipes going into the side of it and they track down to the side of the throttle body and connect to the intake plumbing.
The two PCV valves on the underside of the plenum connect to the driver's side exhaust valve cover ports and this is where the suction to pull clean air comes from. These ports on the valve cover sit too low so in a hard right hand turn the oil in the head will sling over to the exhaust valve cover and pool at the port. Under WOT conditions oil will get blown into the PCV pipe towards the pcv valves and as soon as you let off - voila - the PCV valve opens, the oil gets sucked into the plenum and it will smoke like a $2 whore. On top of that, at WOT condition the PCV system does not work on the NA, and on the TT it works in reverse, forcing crankcase blowby OUT of the intake valve cover ports and into the intake pipe of the turbochargers. This system simply sucks donkey dick. Not only does it smoke, but that oil you are burning significantly lowers the octane rating of fuel. This CAN lead to a blown engine and trust me, rebuilding a VG is not a walk in the park. The solution? Eliminate the use of manifold vacuum as the scavenger. Ok, that's easy, just plug up the ports?? Well, you can't eliminate it so that wont work. Catch can?? No, oil vapor will still make its way into all the same areas in the intake - we want to ELIMINATE that effect completely. Ok Ash, then where the hell do we get the scavenger? A.I.V. baby. Yeah, that's right. That useless pile of shit actually has a very useful component in it. Its called a reed valve. Essentially it is a high speed one way airvalve. Ok, well how does that help us? Well, it takes an understanding of the nature of exhaust systems. Briefly, when a piston enters its exhuast stroke, there is still hot gases in the chamber that are wanting to expand. As soon as the exhaust valves crack open, that air rushes out - accellerating the entire column of exhaust gases in the pipe all the way out the muffler. That column of air is actually pretty heavy. Well, once the exhuast gases are expelled from the chamber, the valves closes. At this point you have a column of gases that are moving pretty quickly and you have now capped off the end of their pipe. What happens now is what we are interested in. The part of the exhaust closest to the exhaust valve 'feels' a sudden pressure drop as the accelerated air continues to want to move. This vacuum is a great scavenger - one that can be put to good use. :) This is where the AIV valve comes into play. If we can use the AIV's ability to harness just the vacuum side of the pulse, then we can use that to draw gases out of the crankcase. Well, wont we still have the same problem with sucking oil? Well, yeah, if we left it hooked up like Nissan did. The fix here is to pull the crankcase gases from the highest point. That would be those towers on the intake valve covers! Put an elevated breather filter on the exhaust valve cover ports and let that be where the air ENTERS the crankcase. No more oil! So now the AIV boxes are pulling crankcase gases (no oil) into the exhaust tract. 
In the last picture here you can see a large diameter hose (about 3/4") running between the wheel well and the power steering resovoir. That runs over to a small aluminum box, which happens to be the AIV valve. The other end dropping into the bottom of the engine bay hose connects at the other end to the metal pipe I welded to the exhaust. The other side of the AIV box connects to the intake valve cover port on the same side of the engine, although you can't see it as I routed it under the intake pipes. I pulled the hose running to the valve cover loose from the AIV box to feel the vacuum. Holy christ there's very strong vacuum pulses and a lot of them so the flow is good. It will definately ventilate the block. TO boot, when you get on the gas pedal, the intensity of the pulses increases both in amplitude and frequency so the PCV system will actually work BETTER at higher load conditions rather that not at all! :-)
[ ashleypowers.com ]
[ agpowers@bellsouth.net ] When pigs dance, you better get it on video...
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PCV system reroute - no more burning oil! WooHoo! - 
09:27:20 09/30/02
