Okay to vent PCV catch can back to turbo intake?

[thinkV]

Hi all,

Recently installed the Radium Dual catch can on my turbo setup.

I was wondering if it's okay to route the pcv can back into the same vent line as the crank case can and both plug into the turbo intake?

The instructions say to have the pcv back into the manifold, but I am hearing mixed reviews and my mechanic didn't want to route it there.

And will it get enough vacuum there?

[Northwest86]

Ok the PCV can routes from the PCV back to the intake manifold exactly as in the instructions. The only thing I did differently was add a 1 way check valve on this hose so that manifold pressure doesn't hit the PCV valve in case it ever fails. Basically a double failsafe.

The Right hand Can connects to the Crankcase breather which is the hose by your oil filter. This routes from the crankcase breather hose to the can and then back to the intake pipe right before the manifold. If you put it before a turbo or supercharger on the intake line all it will do is feed boosted air into the atmosphere before the turbo. Which would decrease its efficiency and power hugely.

Now this right hand can personally I just vented to atmosphere. This is a preferance thing and while technically not legal, whose ever gonna know.

Hope that helps.

[thinkV]

Originally Posted by Northwest86

Ok the PCV can routes from the PCV back to the intake manifold exactly as in the instructions. The only thing I did differently was add a 1 way check valve on this hose so that manifold pressure doesn't hit the PCV valve in case it ever fails. Basically a double failsafe.

The Right hand Can connects to the Crankcase breather which is the hose by your oil filter. This routes from the crankcase breather hose to the can and then back to the intake pipe right before the manifold. If you put it before a turbo or supercharger on the intake line all it will do is feed boosted air into the atmosphere before the turbo. Which would decrease its efficiency and power hugely.

Now this right hand can personally I just vented to atmosphere. This is a preferance thing and while technically not legal, whose ever gonna know.

Hope that helps.

I thought the PCV just needs vacuum to activate? So couldn't the PCV catch can vent into the pre turbo intake and it will have vacuum to suck it through?

Also both can be vented to atmosphere correct?

[Northwest86]

The PCV side you need to connect to the intake manifold. This allows the state of when off boost or when idling for the PCV to open and allow flow from the crankcase. In this state air will flow through the Crankcase breather into the engine since the space has to be filled with something. Usually if your system has some sort of filter you can vent to atmosphere on this one as you don't really want unfiltered air in your engine. This is why the crankcase breather goes after the filter but before the turbo.

You can't run the PCV from the same spot in the intake as if you are under boost you'd have a vacuum source for the PCV. But the crankcase breather would then also be under vacuum causing no flow anywhere.
So simply Intake manifold>Catchcan>PCV (Add a check valve as to allow flow from the PCV to the intake but not the other way if you like)
And Crankcase breather>Catchcan> Either; - Between Filter and turbo
- or a filtered vent to atmosphere (probably not legal)

[thinkV]

Originally Posted by Northwest86

The PCV side you need to connect to the intake manifold. This allows the state of when off boost or when idling for the PCV to open and allow flow from the crankcase. In this state air will flow through the Crankcase breather into the engine since the space has to be filled with something. Usually if your system has some sort of filter you can vent to atmosphere on this one as you don't really want unfiltered air in your engine. This is why the crankcase breather goes after the filter but before the turbo.

You can't run the PCV from the same spot in the intake as if you are under boost you'd have a vacuum source for the PCV. But the crankcase breather would then also be under vacuum causing no flow anywhere.
So simply Intake manifold>Catchcan>PCV (Add a check valve as to allow flow from the PCV to the intake but not the other way if you like)
And Crankcase breather>Catchcan> Either; - Between Filter and turbo
- or a filtered vent to atmosphere (probably not legal)

Thank you for that explanation, it's been difficult to get such clear answers.

I had another query, I recently changed to the correct plumbing as you have stated, and started getting the P0170 error code. Could this be related?

[paintdude258]

I recently started getting the P0172 code. Turns out the simplest of answers was the correct one. My MAF sensor looked clean as a whistle, but the moment I took it out and cleaned it with electrical contact cleaner, my car has never run better. Good luck tracking the answer down!

Originally Posted by thinkV

Thank you for that explanation, it's been difficult to get such clear answers.

I had another query, I recently changed to the correct plumbing as you have stated, and started getting the P0170 error code. Could this be related?