Catch can options
Can you see the hose going from the turbo inlet to the OEM valve cover fresh air? Notice there is no can. That hose is my engine's life line. I pull the hose and check for oil residue once every couple months.
If I ever find even a hint of oil. I can start getting ready to replace the engine. There will never be any can for my application (daily driver). But some applications do require external oil storage. Its just a bad sign to them on daily drivers is all.
Just do what you drew here. You CAN* if you want remove the breather from the can, because it's really only there in case there's too much for the single line going to the filter to vent preventing your rear seal or something from blowing out.
It'll suck through the can when you're not in boost, and when you're in boost it'll vent/suck back through the filter and then if needed out through the breather.
-2 x 10mm line from each valve cover to inlets of catch can
-1x 10mm line from outlet of can to inlet manifold (check valve in line)
-breather filter on oil fill
-valley port blanked.


I really don't need a check valve in the line going from the outlet (clean side) of the catch can to the supercharger inlet barb, since there is only vacuum present there ... However, my catch can is of the Gen5 PCV type, so there is a one-way check valve already installed in the outlet (clean side) fitting of the catch can.
BTW ... I could not close my hood when the catch can's top mounted filter was attached, so I removed it and sealed off the top cap (see photo below).
Attachment 48348744

Last edited by Turbo6TA; Mar 30, 2019 at 09:26 AM.
its strange how MM vent driver valve cover / blank valley on one boosted setup and the opposite on another. So valley blanked and driver valve vented.
I wonder if I could use a small breather filter on the oil cap OR valley port and it be sufficient.
Last edited by SteveSierra; Mar 30, 2019 at 09:52 AM.


Like I mentioned before, the MightyMouse Gen5 "PCV" catch can already has this check valve.
https://www.mightymousesolutions.com...t-page/pcv-can
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Last edited by Turbo6TA; Mar 30, 2019 at 10:02 AM.
E][quote]
This setup is not ideal
1.Is there any PCV for idle/cruise, the most important purpose of PCV for daily drivers? It says "vacuum" but its on the TB Snout so I am not sure
2. the fresh air vent tube is at a small, undesirable location. The flow rate off the valley is insufficient to support pcv by itself. The valley covers are intended to be supplementary crankcase flow, not a stand-alone source.
To fix this system
1. Move the line going from the can to the intake manifold vacuum and install a 1-way check valve (PCV valve) If it doesn't have vacuum or a valve (can't tell)
2. Utilize the other valvecover for fresh air vent source by moving it to the pre-throttle body (or pre compressor of super/turbo) as in other pictures.
You can leave the valley vent or not, it doesnt matter, however it was never intended to be used by itself.
A pcv system is one of those things you can connect or utilize completely incorrectly and have no idea that its wrong sometimes.
For example if you just ran two -10AN lines from both valve covers to breathers and called it a day. It would "work" fine. But there will be no PCV.
Having actual PCV in the crankcase means looking at a gauge and making adjustments to dial it in. Otherwise using factory OEM components.
Last edited by Kingtal0n; Mar 30, 2019 at 12:09 PM.
-2 x 10mm line from each valve cover to inlets of catch can
-1x 10mm line from outlet of can to inlet manifold (check valve in line)
-breather filter on oil fill
-valley port blanked.
Also the filter is negating all PCV action. You are completely disabling the PCV system by installing a two way filter anywhere. Not to mention it will pull in un-metered air and become untunable for maf cars, and difficult to tune in vacuum situations with varying qualities of air coming in that filter all the time.
Last edited by Kingtal0n; Mar 30, 2019 at 12:13 PM.
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I can also make a more informative version for adjusting pressure and where pressure differentials exist etc... but I think its unnecessary?
Also as to the can. catch can purpose is to catch oil. So if the engine starts blowing oil on either side (right side from WOT with a broken piston, or left side due to poor maintenance/baffle performance) you can always add a can to either side. In most FI applications I put a can on the right side (fresh air side) to keep oil out of the compressor (super/turbo). Left side isn't supposed to give any trouble because OEM design their baffles to prevent oil from engaging this line. So if you are seeing oil there (on the left intake suction side) its probably due to a clog, carbon buildup, damaged baffle, improper hose route, poor maintenance, etc... and not the way the system necessarily started out.


I really don't need a one-way check valve in this vacuum line because there is no positive pressure in this line even during boost (just the way this SC is designed) ... In my case, I did buy the "PCV" version of the MM catch can which does include a check valve screwed into the catch can 'Outlet', but in my application, it really is not necessary.
BTW ... The 'filtered fresh air' line that attaches to the crankcase valley cover barb is just that ... filtered fresh air that enters the crankcase ... It gets it's filtered air upstream of the throttle body between the throttle body and the air filter element.
Attachment 48348247
Last edited by Turbo6TA; Mar 31, 2019 at 07:49 AM.


When you put a picture of a vacuum hose attached near the TB you need to specify which side of the blade it is on. Otherwise it is confusing to anyone looking at it. Its like putting a number without units, I have 100boost. 100 what? 100 kg/cm^2 or 100kpa or 100psi or what I can't tell
I changed the diagram showing the position of the throttle body:
Attachment 48348247
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