[200q20v] Audi 20V Turbo Crankcase Breather System Tunin g

tommy.arnberg at nokia.com tommy.arnberg at nokia.com
Thu Nov 2 10:16:04 EST 2000

Hello !

Some new comments.

- vented = the pressure gets out of the system 
 to free air somehow
- the pressure has to come out, otherwise...BANG and oil every where...
- it can be done several ways:
  * burning in the engine near the valves (Factory method)
    (by the way, imagine how the burned black stuff enters the CATs...)
  * letting the crankcase and valve cover fumes into free air
    (this is illegal, but...)

- the carbon canister system MUST be connected to inlet manifold
   but doing so that the black back flow preventing valve (part number 6)
   is taken out of use and connection closed at end of #11

   This could be the new system (page 2 and 3)

- Carbon canister fumes are needed during vacum (idle also)
  conditions to make the mixture richer. 

> Anyway,  Tommy A. seems to believe the device should be  a _vented_
> oil-separator, whereas I had assumed that any oil collection 
> device would  need to maintain the closed crankcase breather system. Tommy

> says (of the bottle w/vented cap):

> >This "vented thing" is very handy and important because
> >the oil/air -pressure has to come out of the system
> >when the original connection to Turbo charger
> >input is disconnected !  And the bigger the
> >hole is the easier is the pressured air to come out !
> My own naive view is that you need to maintain a closed loop 
> and just take  out as much oil as possible from the crankcase air flow 
> before it reaches the MAF, turbo, IC, MM-hose or IM. Seems to me that the 
> "vented" approach will have inherent problems 
> (unmetered air, carbon canister fumes, etc.)

It would be ideal to have perfect separator and collector 
and averything in closed system. I hardly belive that it would be "optimal"
from high boost point of view. When optimal it would be much better 
than the factory solution !  
> whether or not the oem crankcase pressure regulator is at fault if
> excessive quantities of oil are observed ....

I do not belive that the oem crankcase pressure 
regulator is fault because it does not prevent the 
Oil fumes getting into the valves
- the pressure goes either through Turbo (high boost condition) 
  or  when in vacuum condition then through
  back flow valve #6 and rubber hose #11 or #11a
   to inlet manifold and then to valves
- during boost the valve #6 is closed  
  (try to blow air through it the other way !)
  (when pressure at both sides of #6 then the net flow direction is tricky

In the factory system, when connected correctly there is a part of 
"poorly metered air", during boost.  I assume that, when the extra air/fuel
through crankcase breather system the mixture is not corect any more
for reburning. The main mixture gets ~leaner when  A LOT  of crankcase
 fumes get into Turbo and further back to valves. This applies for older
 with high boost.  

This is not so simple thing and I would like to hear some comments  !!


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