This is a great thread. If any of you ever decide to have a PCV valve with a larger inside diameter machined out of aluminum, count me in on the deal.

It also seems interesting to me that everyone thinks a functional PCV valve that creates crankcase vacuum is better for performance than eliminating the burned gas and oil from the air flow into the plenum. I wonder if that's actually true.

 

Great thought - vapors don't have to travel from the driver's side across to the passenger side - both can exit at the center. The PCV would have to be drilled out to allow fresh air in.

Okay, I'm sending my manifold off to be powder coated, will see if I can snap a pic of the opening on those nipples on the inside of the valve covers...

 

Looks like 3/8" tubes at the front of each valve cover. Does anyone have a picture from underneath the valve cover handy? I'd like to see if there's any downside to venting from the center ports that connect the two valve covers.

EDIT, found this:



Looks good - this should double the flow capacity for evacuating cc gases. Nice thought Rmedicx!

 

This is how I've solved it

 

Yep that works. Only thing I have added is vacuum applied from turbo intake to catch can 2. Catch can 1 is an open breather to both drilled out PCV and driver's side rear port (to allow ventilation). Check valves in place to maintain vacuum in crankcase.

 

Oh, good point got to breath both vale covers though can 1. Do you use check vavles there as well (but turned at the opposite direction)?

 

I have a check valve point away from the plenum (like you except mine is "after" the can and closer to the plenum).

I have a check valve point towards the turbo intake (to prevent air from going from the turbo intake into the plenum during idle and during surge conditions when the recirc BOV opens).

Both of these provide suction to can 2, which draws out vapor from both valve covers as you diagrammed. For me can 2 does not have an open breather. It is a sealed system.

I do have an open breather on can 1 BUT don't use check valves with can 1 just in case can 2 cannot breathe adequately enough, then all 4 ports on the valve covers can be used to evacuate gases though I hope most of the time can 1 will be drawing in fresh air and feeding it to both crankcases to allow ventilation.

Since can 2 is where most of the oil will be going, I'm changing out my DIY can with a larger baffled version from the corvette builder in Florida (like the elite can, http://www.mikenorrismotorsports.com/). It is back ordered though . Getting some powder coating done during the downtime though.

 

Great thpughts rcdash! I just love your highly qualified aswers
So I'm lchanging my system to this

 

Yep - that looks good. Mine is nearly identical except I use the pre-compressor intake piping as a vacuum source during boost. What do you do with the rear driver's side port?

 

question for you guys.. why is catch can #1 necessary? Isnt that for a fresh air source? The only reason you would want the catch can there is in case it pukes oil out correct?

 

So much info: But it confuse me a bit. I hope i got this right. So here is my ghetto diagram.

Here is the catch can I'm using, keep in mind I have a G35. I will be adding extra ports.

 

^^^ If you orient the check valves correctly, I think that will work.

I've gone through another iteration of re-plumbing. The crankcase breather setup works, but it does dump fuel vapor out. You can minimize that with the plenum attachment for the hard vacuum on decel, but I ended up collecting more oil in the plenum than I wanted, even with the catch can in place (with the baffle, filter, etc).

Now I've gone to a design recommended by Joe Kenefic (the "MadScientist"). I have reconnected the central hose between valve covers and I'm running both passenger and driver's side vent to a greddy catch can that has been baffled with metal mesh screens and vacuum is provided from the driver's side turbo intake with a Krankvent valve in place (http://www.et-performance.com/). I haven't tested this out yet.

 

This sounds like it will work well with blow thru MAF setups. I am having trouble tuning my UTEC at low load and idle with a blow thru MAF. I did some testing with the pcv plugged and idle improved quite a bit. The PCV is sitting there just pulling air into the plenum and is basically a pre MAF vacuum leak. I have my drivers side hose connected to the turbo inlet just like the JWT kit.

 

Time to bring this thread back to to life. I been very busy these last few months, that I didn't have time to thing about modding.

Anyway I sent my pic to a friend of mine and this was his reply


Now I feel----> I'm going to try to make another pic base of the info of this thread, I'll post as soon as I'm finish.

 

Wow, that's a little convoluted. You just need to use the manifold for vacuum during idle/decel and use the turbo intake as vacuum during boost. You can get away with one catch can by using check valves to ensure air only leaves the catch can regardless of boost/vacuum in the manifold. Or you can use 2 catch cans but you still need a check valve to prevent boost from the manifold from going back into the catch can. Some folks ONLY use the turbo intake. I tried that but I would get some smoking at idle (either out the tailpipes or out the engine breather if I used an open breather in the engine bay) so I went back to using the manifold for vacuum during idle (generates 5 psi of vacuum in the crank case).

 

Here's what I did:

1. Removed pass side PCV, installed 5/8 barb
2. Ran a separate hose from each valve cover to Greddy catch can
3. Vent catch can to atmosphere through small filter

No smoking under boost, no smoking at idle, no oil in intake. Does its job perfectly.

 

Do you have any pictures of the engine side of your setup?

 

any check valves installed in those lines?

are you using MAF tuning with this method? if so how did it affect the tune (if any at all)?

Did you just cap off the original barb on the plenum that used to connect to the pcv valve?

how does this affect the vacuum on the valve cover at idle (since it won't have a vacuum source anymore)
This sounds like the simplest way and i like that.

 

I can try to get some.

 

No check valves.

Using speed density with the Haltech. I'm actually getting ready to install a a separate AIT sensor in the plenum and ditch the MAF sensors completely.

Yes.

My take on the whole vacuum thing is this: when 'positive pressure' builds up in the block, you should not need any vacuum to help draw it out.