Different PCV routing

[eclipsh]

I have been testing an alternative plumbing option for catch cans that I think could work very well. I am making extra use of the PCV valve port by routing an additional line off of it to the intake pipe with diaphragm style check valves on each line.

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I replaced the PCV valve with a 1/8" pipe fitting I drilled out to maximize the ID. I then routed this to a cheap, temporary catch can I made from a spare power steering reservoir. From that can I have two lines exiting, one to the PCV port on the intake manifold and one to the intake pipe. Both exit lines have a check valve set up so they can only flow out of the can, not back into it.

When the manifold is at higher vacuum than the intake it shuts check valve 2 and only pulls fumes into the manifold. When the manifold is under pressure it shuts check valve 1 and only pulls fumes through the intake pipe.

I'm really not sure what happens when both tubes are pulling strong vacuum but it hardly matters so long as one of them is evacuating the valve cover, which they most certainly are. I verified this by checking the hose going to the valve cover during idle.

This setup can be further enhanced by using a catch can on the other breather line and upgrading the port to a 1/4" pipe piece.

 

[eclipsh]

I didn't realize someone had cut this post from another section and made it into a thread. I've updated the original post with a picture and better description.

 

[greengoblin]

Is there ever enough vacuum/pressure under boost to open check valve 2?

 

[eclipsh]

I'm using the 3/8" kynar check valves from US Plastic. I haven't put a gauge on to see if the vacuum line is opening under boost but the manufacturer specs say it only takes 2 inHg to open the valve. Since the whole system is based on their being positive pressure in the valve cover then the pressure differential should be more than sufficient to pop the valve open.

Once I make a more permanent catch can I'll be increasing the size of the valve if possible.

This 1/2" brass valve might be a nice option for higher flow. This male/female valve could also work.

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[BeatupVR4]

So what's stopping the oil vapor from the side port going into the intake tube and through the system? You're defeating the purpose of a catch can. The side port needs to be tee'd into the "IN".

 

[greengoblin]

A dual catch can setup would be ideal for this.

But if the pressure is taking the path of least resistance there is a very real chance it is not and it's just added weight and overly complicated. In for test results. Hook a pressure sensor up or your boot gauge and see if it is worth it. I like the idea. As a matter of fact I had my car setup tis way years ago but deemed it not woth it since one line provided the venting I need for my setup.

 

[ZenkaiRacerDsM]

This is how I planned to run mine, but without the check valve in the line going to the intake.

I'm not seeing the need for the check valve going to the intake. Why is it there?

 

[greengoblin]

So when the car is vacuum it only pull the air from the crankcase.

 

[eclipsh]

So what's stopping the oil vapor from the side port going into the intake tube and through the system? You're defeating the purpose of a catch can. The side port needs to be tee'd into the "IN".

I am actually running a catch can on the other line, i just didn't bother to draw it as I was still making one when I posted this. The side port has to be able to pull fresh air into the valve cover from the intake at times. This is why you need to run two catch cans if you're keeping the "stock" valve cover breathing system. It cannot just T into the single can.

This is how I planned to run mine, but without the check valve in the line going to the intake.

I'm not seeing the need for the check valve going to the intake. Why is it there?

We want the intake manifold to suck dirty air from the valve cover. Without the second check valve the manifold would also pull in fresh air from the intake pipe which would likely reduce the air pulled out of the valve cover. It would also bypass the throttle body as a means of introducing fresh air to the combustion process which probably isn't ideal either.

But if the pressure is taking the path of least resistance there is a very real chance it is not and it's just added weight and overly complicated. In for test results. Hook a pressure sensor up or your boot gauge and see if it is worth it. I like the idea. As a matter of fact I had my car setup tis way years ago but deemed it not woth it since one line provided the venting I need for my setup.

My thought is that with both intake pipe lines seeing vacuum both should be low resistance paths. In this way both should be pulling air out of the system but I won't know for sure until I stick a gauge on it. My boost gauge is digital and runs of my MAP sensor. I'll look into getting a pressure sensor to attach but it will probably be a while. Right not I'm working on finding demister pads for catch cans so they actually do some good.

 

[REVELATION_34]

i may be stupid but why would the valve cover need fresh air??? the side port is there to hook to some kind of vacuum source to help pull positive crank case pressure out not put it back in idk you lost me on this one as to why your motor needs clean air sucked into the valve cover that kinda defeats the whole purpose of a pcv system

 

[ZenkaiRacerDsM]

The intake is under vacuum. It's sucking air from the crankcase.

 

[92AWDTalonTSI]

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Simple.

 

[steve]

Keep in mind that one of the things the PCV does it meter the flow of vapor into the intake. If you car only operates at idle or WOT this might not matter but it you drive it on the street it can make a big difference.

 

[eclipsh]

i may be stupid but why would the valve cover need fresh air??? the side port is there to hook to some kind of vacuum source to help pull positive crank case pressure out not put it back in idk you lost me on this one as to why your motor needs clean air sucked into the valve cover that kinda defeats the whole purpose of a pcv system

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

Keep in mind that one of the things the PCV does it meter the flow of vapor into the intake. If you car only operates at idle or WOT this might not matter but it you drive it on the street it can make a big difference.

Didn't think of this since I'm running speed density but it could matter for people using a MAF. It didn't change the way my car runs at all.