Hi,

had a conversation with a friend lately.
The crankcase ventilation on my 1.8t build is going to the outside into a catch can.
It is not connected to my intake anymore. This is what you see very often on the internet.

His argument was the following:
Lets say there are 10% of boost going by the pistons as so called blow by gas.
Theses 10% were measured and would recirculate into the intake "post" maf on a stock engine.
I miss these 10% air mass and my engine should run too rich.

My trims are unter 5% so i was under the impression every thing is fine.

 

Commenting to subscribe, I'm curious.

I had my PCV venting to atmos, but got bored of having a constant oily smell in the cabin, so it's not vented into the inlet again (via a catch can).

Will wait 5/10k and pull a hose to see the colour.

I want to hear a discussion about this, rather than argue, but why do you think this?

Surely blowby will occur all the time - so during compression the air forced in (especially during FI) will be pushed past the rings into the crankcase.

I understand that exhaust gases will be under much more pressure, but a common test for blow-by is to pressurise the inlet and watch for excessive crankcase venting - hence the blow-by..

I was always under the impression the crankcase liked a small amount of vac on it. On all the big turbo stuff we've done, we almost always set it up like the factory has it.

Guess that's this thread done then.

/endthread.