PCV and Catch Cans

[wilbo666]

I'm looking at how to do the plumbing in regards to PCV / Catch can for the new engine.

I did a bit of a read up on PCV systems (http://www.autoshop101.com/forms/h63.pdf)...and I'm happy to leave the PCV valve... (Who cares if a little bit of oil gets burnt in the intake at low load The benifit is less HC filled air in the sump contaminating the oil...)

It seems to me the only condition under which the catch can is needed is boost...
where PCV valve closed & High blowby -> oily air goes out to intake -> turbo inlet -> engine...

So if I put the catch can in between the intake (pre turbo) and the outlet back to the cam cover I should cover this scenario...

...

Other thoughts...
>Ideally a one way valve in the 'drain' would be good... or should I simply add a tap...to stop the drain effectively short circuiting / bypassing the PCV system...



Cheers
Wilbo

[rob]

seeing the watery oily p00ey mixture that collects into a catch can i'd be hesitant in letting it drain back into the sump

[TERRA Operative]

Me too, I would just put a valve on the bottom of the can so it's easy to drain.

You will need a non return valve on the drain if you want to use one, otherwise the blowby will blow up through the drain pipe and carry lots of splashed oil from the sump with it.

[The Witzl]

i agree.... the mess that collects in my 18RG catch can is NASTY!!!

looks like the scum left when you leave an oil tray (with some oil still in it) out in the garden for a few months to collect rain, leaves and all other sorts of nasties.

Just check it regularly and empty it

[wilbo666]

Yep, decided against the drain for another reason too...

It effectivly short circuits the PCV system under normal conditions... and as such would send a whole lot of oily air into the turbo via the drain -> out, and then intercooler... exactly what I was trying to avoid! Exactly as Terra describes!

Thanks guys

Cheers
Wilbo