Oil Catch Can/pcv Setups...

[Samon]

G'day guys,

Been doing a fair bit of reading on SAU and other places regarding blow-by, catch-cans and the good ol' PCV valve.

For now, let's assume we don't want to vent to atmosphere - i know we probably do, but for this argument, let's pretend we don't

It seems there's two trains of thought regarding blocking the PCV. Some say you need to leave it intact if you're not venting to atmo, others say it's best to block it.

I'm trying to get my head around which is actually better, and why.

The way I understand it, in 'stock' configuration, the PCV allows the engine to breathe into the intake manifold while under vacuum, and closes under boost, when it can breathe via the exhaust side hose into the pre-turbo intake pipe.

If we were to just block the PCV, and change nothing else, wouldn't it just mean that all of the breathing would happen via the turbo inlet pipe? Aside from the large amounts of oil that would be pushed into the intake, are there any other issues with this?

If we then put a catch can with a decent oil/air separator setup in between the rocker cover and the intake pipe, wouldn't this allow the engine to breathe as required, without pushing any oil directly into the intake manifold and reducing the octane rating?

I figure I must be missing something here - mainly because of this: Nissan put a PCV valve in there for a reason - it must be required for something I'm overlooking!

[DVS JEZ]

The way i see it leave the pcv alone and remove and block the intake side at the turbo. This actually pulls oil out ofthe head in a way. There is alot of vacuum there.

[Samon]

The way i see it leave the pcv alone and remove and block the intake side at the turbo. This actually pulls oil out ofthe head in a way. There is alot of vacuum there.

I'm aware of how that works - but wouldn't it be better to prevent as much oil vapour from entering the intake as possible? does it actually *need* to be 'drawn out' - isn't it enough to just let it breathe 'naturally'?

I'm trying to work out what the 'reason' behind leaving the PCV setup stock and allowing it to breathe into the intake manifold is...

[HYPED6]

This is my setup. Yes you need to draw Crank case ventilation from your engine. Believe it or not, you actually want vacuum in your crank case to help pull the ring down on to the ring land of your piston which also helps the push the ring against the bore.

Leaving the tube from your rocker cover to your turbo helps the no end.

Following the diagram, All the red lines are contaminated with oil, all the blue lines are scrubbed from vapor by baffling and steel wool in the oil air separator.

This setup is completely sealed and legal. It never needs to be drained and has 0 maintenance.

I just leave my dipstick tune in my boot and use it when necessary.

Edited November 25, 2010 by HYPED6

[joeyjoejoejuniorshabadoo]

epic drawing skillz

also love the nazi turbo

[FineLine]

epic drawing skillz

also love the nazi turbo

Very constructive contribution to the thread joey.

[Beer Baron]

set-up pictured looks fine to me.

[HYPED6]

And it has PVC...... Positive ventilation crankcase.... oops

Yes my paint skills are awesome. There is no doubting it. As you could imagine its much easier to explain with a picture than using 1000 words.

[r31slpr]

This is my setup. Yes you need to draw Crank case ventilation from your engine. Believe it or not, you actually want vacuum in your crank case to help pull the ring down on to the ring land of your piston which also helps the push the ring against the bore.

Leaving the tube from your rocker cover to your turbo helps the no end.

Following the diagram, All the red lines are contaminated with oil, all the blue lines are scrubbed from vapor by baffling and steel wool in the oil air separator.

This setup is completely sealed and legal. It never needs to be drained and has 0 maintenance.

I just leave my dipstick tune in my boot and use it when necessary.

wouldnt this setup still have the same effect if used without the pcv and line? also what do you have in the catch can to stop steel wool fibres from being sucked up?

[lookingforboost]

do you have a pic of that setup in the engine bay

[T04GTR]

lolzz. looks pretty functional.

[chiksluvit]

has anyone ever had issues with the intake sucking bits of stainless steel wool with the recirculating setup?

that's my setup exactly, though i've never had any steel wool ended up in the turbo, i'm just a bit paranoid that this may happen

[simpletool]

I've wrapped all the steel wool in 4 layers of stockings. Make sure you get the thicker quality stainless steel and wrap in a few layers of stockings (not the thin soapy pads).

[chiksluvit]

yeah thought about that.. problem is i couldn't because of the way the catch can is designed- can't open it up

i could only stuff the stainless steel wool in through the fittings

i'm using the thicker scourer type of steel wool, not the cotton look-alike soapy pad type

Edited November 30, 2010 by chiksluvit

[lachlanw]

pcv is there because what comes out the engine breathers is no good for the environment and counts as part of total emissions and the easiest way to deal with it is to burn it (cheap skate factory. well i dont blame them really )

block the pcv . no oil shit stinkin up the intake manifold

run a decent air/oil seperator baffled catch can between the rockers and turbo intake . no oil in anything systen still sealed . engine breathes fine because there is partial vacuum between the afm and

[kristafa]

hard to jump in after the paint-master HYPED, but here goes..

I have welded a fitting onto my turbo oil drain on the block (hot-side), as setup as follows

I haven't planned on using the PCV, any problems with this setup? i haven't used it yet, the car is due to turn over in a couple of weeks.. This thread had me thinking, under boost, could i possibly be sucking oil up the oil drain and into my catchcan?? i'm guessing the turbo inlet pipe produces a vacuum but unsure to what extent..

[bubba]

wouldnt this setup still have the same effect if used without the pcv and line? also what do you have in the catch can to stop steel wool fibres from being sucked up?

Yes, if you block the PCV valve and the return line, you would just put little filters on the top of the catch can to run atmo.

hard to jump in after the paint-master HYPED, but here goes..

I have welded a fitting onto my turbo oil drain on the block (hot-side), as setup as follows

I haven't planned on using the PCV, any problems with this setup? i haven't used it yet, the car is due to turn over in a couple of weeks.. This thread had me thinking, under boost, could i possibly be sucking oil up the oil drain and into my catchcan?? i'm guessing the turbo inlet pipe produces a vacuum but unsure to what extent..

I'd be worried about introducing that kind of vacuum to the turbo oil return...

[kristafa]

any particular reason?

[bubba]

It would be drawing air from the crankcase via the the turbo drain.. air that would be flowing against the oil trying to drain out of the turbo (could there be enough vacuum at high rpms to pull oil up in to the can??).. the oil is not under any pressure but neither is the oil trying to flow back from the head down the factory drains (the reason why we go to these breathing extremes).. It would also mean there is a constant vacuum (fed in part by the drain) in the can which probably wouldn't help the oil to drain.

I dunno, I just wouldn't screw with it is all

Edited December 1, 2010 by bubba

[gotRICE?]

I had issues with my PCV being blocked causing the engine to smoke when taking off.

Put it back to factory PCV, with vented breathers and haven't had the smokey problem since.