Hi everyone, this is my first question to the Corvette Forum, and while my account is only a few months old I've been frequenting the forums for the past year now. I've read over dozens of oil catch can threads and have learned a lot about why one is needed, however I'm still confused about the setup and as such am creating this thread.

Mods done to my 2004 C5 Z06 include;
- Magnuson MP112 supercharger (non-intercooled version)
- Alky control meth pump running 100% methyl-hydrate
- LS9 cam
- LG long-tube headers
- McLeod clutch
- Cat delete with stock mufflers

When doing oil changes I was originally running Mobil1 5W-30 but was getting absolutely terrible oil burn, I was burning a quart in under a hundred kilometers of normal driving. I decided to switch oils and now use Castrol Edge 5W-40 and only get oil burn under heavy driving situations rather than all the time. For example, on Castrol Edge 5W-40 I drove 400 kilometers straight at high speeds and very aggressively (was going 275 km/h a few times) and burnt almost 2 quarts by the end of the trip. Going back the same route (400 kilometers straight) but driving much more civilised (averaging 135 km/h) the oil barely moved on my dipstick.

I still find oil sitting in my intake which I try to clean out regularly but it's because of the amount of oil burn I get that I know I need to install a catch-can setup.

Materials I plan to use;
- 2X PCV Valves; either https://www.rockauto.com/en/moreinfo...t=5052&jsn=933 or https://www.rockauto.com/en/moreinfo...t=5052&jsn=937. I'm not sure which is better, AC Delco vs GM Genuine??
- 2X Oil Catch Cans; eyeing a few on Amazon that look to meet my needs - Mighty Mouse is USD + 34% exchange rate + international shipping = out of my budget.
- 3/8 Rubber Hose (fuel line); unless a larger size is recommended, to be purchased from a local automotive store.

For my questions regarding the catch can setup I've attached the pictures below:
Top Down View:


Currently; my current setup is from the previous owner who installed the MP112 Supercharger;
- #1 - Driver Side Valve Cover and #4 - Throttle Body Intake are capped off.
- #3 - Passenger Side Valve Cover is connected to #2 - Supercharger Intake.
- There are no PCV Valves anywhere in the current setup, and while I know the 2004 Z06 used a different PCV system than prior years this doesn't appear to match the factory setup either.
- There is also a mystery line (in red) going from the Driver Side of the Supercharger Manifold to behind the engine, I haven't found any mention of it on other threads and don't know what it's for. Brownie points for whoever has an idea!!

Proposed; based off what I've seen on other threads I'm looking to run a 3/8 line rubber hose (fuel line), unless a larger size is recommended, as follows;
- #1 - Driver Side Valve Cover to Side B of PCV Valve, then Side A of PCV Valve to “In” side of Oil Catch Can, and “Out” side of Oil Catch Can to #2 - Supercharger Intake.
- #3 - Passenger Side Valve Cover to Side B of PCV Valve, then Side A of PCV Valve to “In” side of Oil Catch Can, and “Out” side of Oil Catch Can to #4 - Throttle Body Intake.

Questions;
- I want to confirm that this would be the correct setup and that the way I plan on facing my PCV valves is correct (they’re not backwards).
- Which PCV valve is better? GM Genuine or AC DELCO, or is there another brand I should be using instead?
- Is the hose size (3/8) I plan to use is the right size - is bigger better??
- From previous forum posts I’ve seen that the PCV valve needs to come before the oil catch can, but does the placement distance between valve cover and oil catch can matter? I.E. should a PCV valve be placed in the middle between the valve cover and catch can? Should it be 3 inches after the rubber hose connects to the valve cover or 5 inches before the oil catch can etc.
- For placement of the oil catch can, does it matter where they are? Do they need to be heat protected from the headers if they're right next to them? Does it not matter if they’re cold or warm?

Driver Side View:


Passenger Side View #1/2:


Passenger Side View #2/2:


PCV Valve (GM Genuine) Reference:



Please let me know if this appears correct or if there is anything I should do differently, thank you!!

 

What happens to the valley cover PCV vent with the supercharger? Is it removed completely I guess? That's normally the primary or dirty side path.

You only want a single PCV valve in the system.... and it needs to be in the line that has a vacuum source. Based on my understanding of this SC system, #2 is your vacuum source. Orient the valve so that air can freely flow into the engine/air intake/blower. It can act as a sort of 1 way valve, but also as a restriction. You don't want "full vacuum" on a valve cover or the crankcase, with that much suction you'll suck up and burn a considerable amount of oil. This is probably the root cause of why it burns so much oil now-- too much suction on crankcase. #4 is actually pulling air from pre-throttle, so it will always be around ambient air pressure, not a real vacuum source.

Otherwise I think the proposed plan is sound.... just run straight hose between #3 and #4. I might even try it without catch cans first to see if it solves the issue. If it is still an issue or you just really want to keep oil out of the blower, put a single can between #1 and #2 only. This will catch 95% of the oil vapors as this is the 'dirty air' path during non-boost engine operations. You don't really want a can between #3 and #4 IMO because this is your primary crankcase ventilation path in boost and you don't want to make the line super long or add a catch can or other restrictions.

 

You are burning and blowing oil because there is no PCV action.

You need a PCV system. Not catch cans. Catch cans will reduce the effectiveness of PCV and cause more oil to blow out of the engine. They will increase the oil contamination of the engine and ruin it sooner.

Some people know this
DO NOT INSTALL CATCH CAN

Catch can destroy engine

Time to wake up!!

The goal of PCV is pressure below atmospheric so that energy supplied by the engine vacuum pumping can reduce oil droplet density and radius. This facilitates oil return to the oil pan, improves ring function which reduces the blow-by and will stop the engine from blowing oil out as long as the compression is good and rings aren't already ruined from running high crankcase pressure. High Crankcase pressure (NO PCV) causes oil to accumulate in the ring pack and gradually sticks them causing excessive cylinder wear and blow-by and then its too late.

Your main goal in life is to
1. Measure the crankcase pressure
2. Set the crankcase pressure properly

If you can set the tire pressure, oil pressure, coolant pressure, fuel pressure, boost pressure, etc... then you can set the crankcase pressure using the same ideology it is exactly like all the other pressures.

There are two sides to the PCV system. Manifold vacuum which is idle/cruise and has a PCV valve or high quality check valve and a metering orifice (the pcv valve is often the metering orifice but not always). The other side of the wide open throttle side. There is no 'clean' side as both sides experience blow-by gas exposure and both sides can experience oil blowing out of the engine when crankcase pressure is high and when that happens there could be some clean oil in the line which is still clean its just oily at that point.

So where do they connect. You have two sides to connect for PCV. In forced induction application in this case you have a blower so there is some manifold vacuum which turns into manifold pressure under boost. You can take any line from below the blower (from the intake manifold, check at idle for idle vacuum and if its from below the blower its fine) and use it for your idle/cruise side with the pcv valve. Note the PCV valve flow directional they flow only one direction, flow needs to be TOWARDS the intake manifold. The OEM chevrolet pcv valves all leak boost so using an OEM pcv valve is a mistake and should never be done in a forced induction application unless you have a specific PCV valve for forced induction and pressure tested the pcv valve yourself and continue to do so as routine maintenance no matter what pcv valve you choose. I always use Toyota Supra 95-02 Twin Turbo PCV valve in my chevrolet application for boost they seal up tightly. I will use two of them in parallel to increase the pcv flow rate for idle/cruise which maintains a cleaner engine and clean engine oil which prolongs engine lifespan. Thus you will have: Intake manifold -> PCV valve -> Valve cover (drivers side usually). Some Chevrolet LS engine have a restrictor orifice in the valve covers so BE CAUTIOUS if yours has a restriction orifice it may not work well for full time idle/cruise part of PCV system and you need to use a different valve cover or location. Location option#2 is the valley cover port which feeds just like the valve cover from the crankcase but it too may have some restriction orifice. Best option here is 1. check for restriction orifice in the driver side valve cover and then 2. get a valve cover with no restriction if you need to.

Next the wot side. Because your blower is not a turbocharger it is a potentially simple setup. You will attach #4 to #3, the blocked throttle body port to the passenger valve cover with no restriction orifice. No PCV valve here. Then, you will absolutely NEED TO MEASURE the pressure at the valve cover, like this


By placing a pressure sensor on the crankcase and measuring the pressure at wide open throttle and while driving to ensure it does not ever never ever rise above atmospheric pressure. Here is a video how-to DIY using a 5v source.


Notice the pressure drops at wide open throttle. If yours does not do this then you will need to move the line from #4 to further up near the air filter pathway. Like where that braided stainless line is, what is that water injection or something up there. It should work at #4 but blowers are fickle in that location it might pulse or something at low throttle positions.

Finally you absolutely need to pressure test the entire setup to ensure the pcv valves are working properly and the crankcase does not pressurize in boost. Here is another video how to do this.

In your case you will fill the intake plumbing from the throttle body since you have no turbocharger centrifugal style compressor housing to deal with. Its much easier for you. You will have the pcv valve popped out and make sure it seals up tightly under boost. You will listen at the oil dipstick and feel at the oil dipstick for air leaking out of the crankcase for any reason. The intake pathway should seal up tightly including the pcv valve. If the connections are correct and the measurement is adjusted to provide pressure drop of 1"Hg to 3"Hg of vacuum on the crankcase at wide open throttle then the engine will maintain cleanliness and no oil will blow out of it and no more smoking or dripping from engine oil seals. Unless they are already ruined of course.