Editing How to install an oil catch can (section)

===Flubba86===

Yeah you're right, with a n/a setup the excess pressure will simply push the pcv back open again because of what you said, low pressures in the manifold. And what you mentioned about using a second catch can, between the rear spout and the air source, is what I have considered many times, but it would be hard to implement due to the fact that the rear spout is sometimes sucking, and sometimes blowing, depending on whether you are in vacuum or acceleration conditions.

Im still not comfortable with the fact you are sucking in unmetered air through the pcv. Every time I have had even a slight vacuum leak in my engine, it would run rough. The pcv sucking air from an unmetered source is just like a MAJOR vacuum leak, and will run heaps lean, to the point of nearly stalling. And that cant be good for your car. I am guessing you havent noticed it because your oxygen sensor might be in good condition and is catching this error and correcting it.

Every person I know who has done the relocation of the AFM to just before the throttle body, has used an XF throttle body in conjunction with the mod, because the XF throttle body has two spouts in its body just before the throttle butterfly (so after the AFM), and you use one for the idle-air source and use the other for the rear rocker cover source, because these two points are now the only places on the inlet tract to get metered air from.

My current setup is what I would call correct for a turbo car, but not legal. Firstly, I have an aftermarket plenum, and zero PCV valve, there isnt even a provision there for one. I have small breather filter on the rear rocker cover spout (for sucking in fresh air) and the front spout is connected, via a catch can, to a spout I have placed just before the mouth of my turbo. My AFM is in my cooler pipes just before the throttle body, so all of this is working outside the zones of metered air. On idle, there is very little suction through the turbo and almost no movement of air though the rocker cover. If there is any crankcase pressure, it is immediately pushed up thought he front spout and into my turbo inlet, just more air to be combusted, and very little oil vapours because of my catch can. On strong acceleration, when my turbo gets a spool up, the air being sucked through the inlet is quite massive and it puts a suction on my front rocker cover line, sucking air through the rear breather, collecting oil vapours and blowbys in the rocker cover, out though the catch can, and into the turbo. The only problem I have with this setup is that there is no vacuum on the rocker cover during idle, so my ticking is a little bit louder, and I can hear the cam spinning around in its bearings etc. But as soon as there is any acceleration, the vacuum is pulled through the crankcase as it should be.
so the pressure buildup in the crankcase wouldn't be much, unless your engine had some serious blowby issues, which would need to be rectified anyway.
as i said in the first post, for track/strip, you would just block off the PCV and put an open vent on the top of the catch can, perfectly legal on the track and no crankcase pressure issues.





'''Compiled by:''' Gemi Coupe