Correct barb size for catch can?
 

I believe the outlet size is 1/2 (0.5") but what about the inlet? I know some people running 0.425" but is that the ideal size or should it be 3/8?

I'm PREEEEEETTY sure its 1/2" for inlet also.

Hmm interesting. People in the DIY are doing 1/2 for outlet and 11/32 to 3/8 for inlet. These sizes are for the tubing.

Im guessing bigger would be safer then smaller, but I rather get the sizing a close to OEM.

I have the D3PE catch can, and I'm sure it uses 1/2 for outlet (I clamped both) I'll check the inlet tonight. It might be 3/8" on the top of the throttle and 1/2" on the other side. I have no inlets as it vents to ATM, but I'm using the top of the throttle as my pressure signal for Gauge and BOV.

I'm 99% sure the inlet is 3/8", the outlet is 1/2". Where 3/8" is the PCV hose and 1/2" is to the intake manifold. You can pull off the PCV hose in about 2 seconds and measure it, it's not clamped or anything.

I'm using the Radium can and I'm using a 3/8" inlet and a 1/2" outlet.

The only thing I don't understand is why it would be different. We are basically just throwing a catch can in the middle of the line right? You would think that OEM line would be the same from inlet to outlet.

I know... but the Designers had others things in mind.. :mad0260:

Wait what do you mean? Do you mean not having a stock catch can or the size of the hoses?

You said the hose size should be same on both sides, I mean the designers had different things in mind because they used reducers to connect the PCV hose from the block to the throttle. Now that I'm writing this its all coming together actually. The PCV side, its 1/2" in the block and 11/32" on top of the throttle.

The Breather side is 1/2" to 1/2", no reducers.

What catch can do you plan on using?

Ahh I see! I'm assuming 3/8 inlet would be a good compromise? Btw, I believe you got the PCV and throttle sizes mixed up. It should be other way around.

I'm planning to go with the Saikou Michi can.

PCV is inside the block, so the conection in the block is 1/2" im 95% sure about that one (Could definitely be wrong!!). The top of throttle body (that is the oulet fo the PCV) is reduced to 11/32" only the designers know why... The breather which is below the AC compressor and connects to the intake tube, im 95% sure its 1/2 to 1/2, maybe I didnt explain it well initially?

This is what is making me confused with the explanation.
This is my config that I submitted to Saikou Michi. I hope it's correct!

http://i2.photobucket.com/albums/y42...5/Untitled.png

-6AN or 3/8ths is the inlet size barb. 3/8th hose can be run from PCV Valve to inlet of catch can.

Output to intake manifold is 1/2" hose and barb. As pictured.
Make sure every piece is clamped and PCV leaks are very common and can cause performance issues.

I was redoing my Pressure signal line and I think you were right and I was wrong.

The inlet into the throttle seemed perfectly 1/2" so that means inlet to PCV is 11/32".