Thread: PCV confusion.. Why are there 2 ports??

I am getting ready to install a ported blower (Gen3) and a ported TB on my L67.. In looking at the PCV configs, I am a bit confused:

1) The standard PCV setup on the Gen 3 blower has the PCV valve on the backside with a hole on top that exits inside the blower casing (after the throttle body completely). Couldn't find a good picture online. can take a picture of the inside of my blower inlet if needed for clarification.

2) The throttle body also appears to have it's own separate PCV entry location on the back-side (connecting side to the blower) as shown below (labeled PCV passage):



This passage exits into the throttle body after the MAF, but upstream of the throttle body blade as shown below:



Why/what are these two separate "PCV" inlet locations achieving? I mainly understand the function of the PCV setup on the blower, but not this PCV setup in the throttle body.

I also am aware of guys opening up the throttle body PCV on the bottom of the L67 throttle bodies for intercooler applications per the thread below:

http://www.grandprixforums.net/threa...cover-breather!

Still don't know why there are 2 ports to begin with though on stock L67 setups.

Thanks in advance for clarifying my confusion

theres no pcv to the tb on a l67 tb. evap is tho.


just what are you trying to do here? bolt it all up and thats that.

This throttle body was opened/tapped on the bottom per the thread mentioned in my original post to accept a PCV vent for the front valve cover since I believe it was previously used on an intercooled setup. I want to make sure I fully understand it before I go capping off any ports that's would actually be needed.

And I agree, I was not aware of any PCV port on the L67 throttle body either. Still seems interesting though that this port exists on the throttle bodies in the pictures I've attached above, as well as the ported one sitting in my hands.

Ive been trying to research this a bunch this evening and my head is spinning haha

http://www.grandprixforums.net/threa...cover-breather! what your talking about is for a pcv bypass when running a ic if you plug the nipple under the tb its like it was never done.