I've got a 2005 Touring. Do I want to put the oil catch can on the line running from the crankcase to the bottom of the air intake tube? Or is that line the "breather tube?"

If that is the breather tube coming out near the firewall, then I guess the PVC tube is on the front end of the engine?

Also, given what I have read on Wiki, the air seems to blow both ways (probably a better way to word that) depending on the load on the engine. To quote Wiki:

At idle, the intake manifold vacuum is near maximum. It is at this time the least amount of blow by is actually occurring, so the PCV valve provides the largest amount of (but not complete) restriction. As engine load increases, vacuum on the valve decreases proportionally and blow by increases proportionally. Sensing a lower level of vacuum, the spring returns the cone to the "open" position to allow more air flow. At full throttle, there is nearly zero vacuum. At this point the PCV valve is nearly useless, and most combustion gases escape via the "breather tube" where they are then drawn in to the engine's intake manifold anyway.

If this is the case, then it would seem important to have an oil catch can on both the breather tube and the PCV valve tube. Otherwise we are not catching any blowby stuff at full throttle.

Any help appreciated.

Thanks

Tom

 

Check this link below. This is the best thing you can do. This catch can is located on the PVC side, where it should be. I've done this about 8 months ago. Works great. On the breather side there's not as much to catch on that side. I had that set up one time and never saw a thing in the can. On the PVC side it fills up once a month for me. But I drive my car hard and it's FI. Also only driven on weekends. So that's not many days at all.

https://my350z.com/forum/engine-drivetrain-and-forced-induction-diy/237059-homemade-catch-can.html

 

Thanks. I'm getting the impression from reading up on this that the breather tube is situated where it experiences a lower vacuum pressure than the PVC side. I believe the PVC side goes directly into the plenum while the breather goes into the air intake tube behind the filter. If the difference in vacuum theory is correct, and given the one-way nature of the PCV valve, the flow should always be to the PCV side.

If the vacuum were ever equal on both hoses, blowby could go up the breather hose.