I'll draw up some schematics for you tomorrow arvo as well as running through hose sizes.

Sorry for the late reply as things have been predictably unpredictable round my way.

Let me rephrase on the right way to plumb up a catch can.

Catch cans normally go between the rocker cover vent and the air intake between the TB and air filter. In your case it would go between the air filter and blower. The slight vacuum there actually acts like a small vacuum pump which helps minimise the effects of blowby.

You can fit an aditional catch can between your pcv valve and intake manifold.The main purpose here would be to try and keep out as much oil vapour from entering the intake as possible. Once mixed with the incoming fuel, oil vapour actually decreases the octane rating of the fuel. An alternate device instead of a bulky catch can would be a compact oil/air separator, similar to what's available for air compressors. A full range of separators is available from Jegs or Summit.

Now for the No No's

DON'T have the PCV and rocker cover vent going to the same catch can, even if it is plumbed back to the intake or between the filter and blower. You have to remember that you are venting the crank case under 2 different conditions (closed throttle and WOT). Trying to do that on the same circuit will cause you nothing but grief unless you install aditional check valves. Just because one hose comes from the back of the intake and the other comes from a rocker cover (or both) they are both venting pressure from the underside of your pistons. Think about how your engine oil drains back down to the sump.

DON'T have your vent lines going to a closed catch can. This is what we did by mistake when we blew all the seals on the old VL. Being a 6cyl both the breather and PCV were mounted on the rocker cover. We had both going to a can with no way for the pressure to escape. Expensive and messy lesson learnt. There must be a way for all of that crank case pressure to escape, hence why it is plumbed into the intake just after the air filter for the breather and as per the factory port on the intake for the PCV.

DON'T vent to atmosphere (even through a small breather filter). Have you ever smelt a breather filter that was fitted to a catch can (not plumbed back) for a while? Damn thing bolwed me over for 6 it was that toxic. And this is the exact same reason why the EPA has banned the use of Vent to atmosphere blow off valves. Noise has f**k all to do with it.

I know I was meant to draw you some schematics but I haven't had much time with it. Will you be coming up to liverpool tomorrow night?

Xcabbi,

Thanks for your response, much appreciated.

I'm running a MAF and from your description, I wasn't sure if the catch can return should be plumbed back before the MAF (after filter and before MAF) or is it to be plumbed back after MAF (after MAF and before the supercharger - same as BOV).

Thanks again.

Once the cars done I should be at the Liverpool meet.

Nathan.

I'm assuming you are running a standard style suck through maf instead of a blow through one? Since the stock vent location is right on the throttle body you could stick it between the maf and the blower. It seems to be the convention according to the US forums. It would be a good idea to check your AFR's just to make sure.
I'll be running a blow through maf so I have to plumb it between the filter and turbo.

Last edited by xcabbi on Fri May 30, 2014 7:12 am, edited 1 time in total.

Have you disconnected the vent at the throttle body ?? Or any where
on the boost part of inlet.
If not you could be boosting your crankcase,,,
Yes have to think about unmetered air entering engine through engine
ventilation..

All,

Its been along time since I have done any work on the car or even been on the forums.

I have tried to upload a diagram of how I have it setup but for some reason it isn't working on this computer (not at home). I will explain it the best I can.

Note: PCV is currently left unchanged from factory. Current Intake Set-Up = POD Filter to MAF to Supercharger to BOV to Throttle Body to Intake Manifold.

1. Drivers side Rocker Cover - Vent from Oil Fill Point to Throttle Body, removed and capped off.
2. Both Drivers Side Rocker Cover and Passenger Side Rocker have 1 x 3/8 Inch Internal Diameter Hose Lines Connected Via 90" Barbs to Catch Can.
3. From Catch Can, 1 x 1/2 Inch Internal Diameter Hose Connected to 1/2 Inch Barb On Pod Filter (rather then venting to atmosphere and as it have come from the crankcase this should have already been metered therefore it is returned to the intake prior to MAF).

I have driven the car (not too hard) and appears all issues have gone. Just want to iron our these few bugs before moving onto the Front Mount Intercooler - which I have been told is difficult.

Any help is much appreciated.

Thanks,
Nathan

Hey mate, I ended up using a vac-u-pan type system, whereby it draws crankcase pressure using vacuum from the exhaust. I am also going to use 2 ctach cans - one for the valve cover filler and the other for the PCV at the rear of the block.

see thread to other forum - http://www.google.com.au/url?q=http://w ... aZnIHQy83A

3. From Catch Can, 1 x 1/2 Inch Internal Diameter Hose Connected to 1/2 Inch Barb On Pod Filter (rather then venting to atmosphere and as it have come from the crankcase this should have already been metered therefore it is returned to the intake prior to MAF). this will affect your MAF readings, particuarly temps, and will also increase you air intake temps reducing power. You will also be sucking in some (not as much as stock though) oil vapour, which will also reduce power by lowering octane rating.

you need to either

1. revert back to stock system, but still use unvented catch can
2. use a vented catch can and vent to atmo
3. use a vac-u-pan system plus using 2x unvented catch cans
4. instal a vacuum pump, hehe $$