Ive tried many different catch can setups and this is the one i have found to work the best.I'm using saikou michi catch cans which IMO are the best out there and they actually do something.You can go to their website and see how they work.Props to tom tscomp for his post on this subject.

Here is hose off of valve cover with pcv valve on it.I highly recommend getting a new oem pcv valve.

This is the hose barb off the intake manifold.

This is the first catch can.I have two 1/2" viteon plastic check valves.They are available on ebay for a few bucks.Note:I am using 5/16" hose since I'm still testing this setup i will eventually go with 1/2" barbed cans if need be but this is working fine.

This is the second catch can.Again I'm still running 5/16"hose.I have a can with 5/8" hose barbs and i also have barb fitting to tap onto valve cover and intake pipe.This is still running fine with an fp black it may require bigger hoses with bigger turbos but I'm not sure.There are no check valves with this catch can.I tried them and they didn't work.basically the turbo is a vacuum pump that sucks all the pressure out of engine while under boost.Make sure your intake pipe is nicely sealed.One may ask if turbo sucks in oil from can the answer is not really because the vapors are filtered out and the oil stays in the can.There is the slightest amount of oil residue but nothing to be concerned about.

 

One question. Couldnt you run the valve cover breather into the same catch can that the PCV uses? Why two?

 

Because under boost can would be pressurized.Can is designed seperate oil vapor keeping oil in can and sending fresh air back into engine.

 

What size barb fitting did you use? Did you screw it to where the OEM PCV valve used to be?

 

stock 8mm barb.Im still using stock pcv valve.

 

Ok. If I'm getting the picture right, you have another check valve after the OEM PCV valve?

 

Yes

 

Thanks for posting this...How did you go about mounting the cans seeing as Saikou Michi doesn't actually make a kit for the evos??? At least i don't think they do

 

I dont understand why you have two check valves. The first check valve make sense because that is preventing boost from pressurizing the catch can. The second check valve seems to be redundant because it is serving the same purpose as the PCV.

 

This is similar to the setup I use, including the dual check valves, however I have my second check valve installed between the catch can and the intake manifold so the can does not get pressurized. The same effect can be had by moving the stock PCV valve to that location, but I found adding a second valve to be a simple fix. dual catch cans



Above is what you need to have, from the pics it kind of looks like you have the check and pcv valves on the same leg which would still cause the can to pressurize.

 

There's different places you can mount it.I mounted it to where ic sprayer was and to where bcs was.
Because Pcv valves sometimes don't seal even when brand new.just for extra security.

 

What cans are you using?can doesn't get pressurized because under boost Pcv is open then goes into can gets filtered goes back into intake.check valve that goes back intake prevents boost from coming back into can.I will make another video showing that I actually get vaccum in engine when under boost.

 

PCV works the other way around, when under boost your intake manifold gets pressuriesed to whatever you boost to, the line that goes from your intake manifold goes through the PCV into your valve cover. At this point the PCV valve closes so you do not pressurize your valve cover.

When you are off the gas your intake manifold goes to vacuum the PCV valve opens and blow by air leaves the valve cover, passes through the PCV and into your intake manifold since the valve cover now has a higher pressure than your intake manifold. It is under this situation that you want the catch can to stop the air with bits of oil from getting dumped into your intake manifold. Under boost your catch can should ideally be doing nothing.

Your Catch can is designed to take the blow by that happens when you are off boost, filter it and pass it to your intake manifold, which is why you need a PCV or check valve between the intake manifold and the catch can.

Oh and for your other question, I'm using some greddy style catch cans from e-bay that I modified to give them a bit of baffling (similar to saikou michi which rock). Fun project.

 

^thats exactly right, except doesnt the PCV vents the crankcase? So when you are in boost, what happens to the excess of blowby when the PCV is closed? And looking at the diagram, if you have a check valve on the valve cover vent then you should be able to use one catch can since the can wont be pressurized.

I ordered some check valves with NPT threads to use and try in a one catch can set up.

 

Yes, I think your right crank case not valve cover my bad, the other one should be venting the valve cover. Either way pressurizing the catch can from the manifold = bad mojo heh.

You also can use one catch can instead of two if you cap the nipple on the intake manifold and the nipple on the intake tube infront of the turbo and then just Vent to atmosphere the catch can. The saikou michi is designed to just stay in the path and not vent the extra gasses. I've heard venting the gasses could have a slightly similar effect to a vta bov, however I don't know if thats true.