[andrew_b]

Nice article, thanks!

[els_86]

I'm sure this has been discussed and it already out there, but what about modifying the PCV so that the vapors exit into the air instead of being recirculated back into the intake system? I know it's not legal for environmental purposes, but either are downpipes lol.

[brickyak87]

Hello els_86, there are plenty of applications that utilize an atmospheric dump of your non-burned fuel vapors. There are definite pro's and con's to using such a system. I prefer a system that contains a catch can with three check valves: one between the can and the intake manifold to keep from applying boost to the can and pcv valve, one being the pcv valve itself, and the other being a check valve at the top of the can that vents to atmosphere. The valve at the top should have a filter on it to keep debris from entering the intake system. You want to avoid applying boost to the pcv valve as it will force the valve closed and begin building pressure in the crankcase. I don't recommend a recirc to crankcase system for any boosted application because if the can-to-intake check valve fails you will dump full manifold pressure into the crankcase.

[brickyak87]

Also to answer Alterzgo, and I know it's a question from a while back but just in case anyone needs the answer still, there are manufacturers that use these in OEM production. Look up BMW's cyclone separator and you'll see what I'm talking about. Instead of using a can to catch the oil once it's separated, it simply returns the oil to the crankcase. It essentially does the same job and is part of the PCV system just as the catch can is. Also, it's a pain in the **** to change these things on the Vanos 4.4's