OK,

I am doing the BavarianE39's mod as we speak.

I am trying to understand why this mod works b/c:

1. I went to Autozone and got the Duralast PCV valve, I just double-checked the design:
a. Blew one way (toward I.M.), it flows.
b. Blew the other way, no flow.
Nothing special, this is the design of the PCV valve, which is basically "one-way street".

2. I also have a BMW CCV Valve lying around:
- Blocked the oil return port.
- Blew at port #2, air came out port #3.
- Blew the other way, no flow.

Don't get me wrong, I am doing the BavarianE39's mod but...

From an engineering standpoint, there is virtually no difference in the 2 designs (Mod vs Stock).
See photo below: vapor + oil is still sucked into the Intake Manifold, so why does this mod work?

Attached Images

 

__________________
1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT