[urq] Too much Crankcase ventalation?

Claus Vegener vegener at post7.tele.dk
Wed Sep 5 03:04:22 EDT 2007

I would love if it was that easy -
Just now I am battling with too much oil in the catch tank.
My block is a WR 83 w/o the lower crankcase breather system connection (came 
in 84 ).
I have placed a 3B 20V head and on top an ADU valvecover with plugs on coil.
This valve cover have an external oil returnline (I have realized now) and 
are just making it working that way.
There is not much room inside the valvecover to find a place, where the cams 
are not splashing oil and a strong accelerations
 - high revs - the valvecover simply gets full of oil.
I have apparently a weak clutch (034EFI 800 Nm) and a 1/4mile where most of 
the 12 sec are at the rev limiter 7800 rpm
can pump 3/4 litre of oil out. (not supposed to 7800 rpm but that happens)
I have a small returnline to the aux oil resorvoir at the 3B pan from a 
Vortex air/oil separator but not big enough.

Claus Vegener

Urq-83 20V 525Hp
200 20V Avant 280Hp

----- Original Message ----- 
From: <QSHIPQ at aol.com>
To: <quattro at audifans.com>; <urq at audifans.com>
Cc: <Djdawson2 at aol.com>; <benswann at comcast.net>
Sent: Wednesday, September 05, 2007 4:59 AM
Subject: Re: [urq] Too much Crankcase ventalation?

> Dave
> A proper crankcase>valve cover oil vapor PCV system, won't suck oil, 
> there
> shouldn't enough vacuum to do so.  IME, oil from launches is a  problem 
> innate
> to the v8's and S cars with the PCV breather  hoses at the back of the 
> head.
> PCV pickup and/or vent should be  dead center in a cam cover to avoid the 
> hard
> launch and hard braking  sloshing of oil.  The reason for a tie-in of the
> crankcase ventilation with  the valve cover, is exactly to act as a 
> dead-air oil
> return chamber  for crankcase oil.  IMO, the 5k's with the double walled 
> valve
> cover had a  better design for PCV than either the later flagship v8's or 
> the
> Scar.
> Regardless, the urq has the same basic system as the 5k's, without the
> problem of oil sloshing.  Ben's issue is strictly too much vacuum  IMO. 
> To fix the
> S-car or v8 problem of oil sloshing in the valve cover, it  should be 
> pretty
> easy to install a traditional ball type PCV valve and gasket  dead center 
> in
> the valve cover, with the vent line placed on top too.
> SJ
> In a message dated 9/4/2007 8:58:00 P.M. Central Daylight Time, Djdawson2
> writes:
> I would  agree that the noise you are hearing is air being sucked past 
> seals.
>  Idle = high vacuum = noise.  Revs higher = low/no vacuum = no  noise.
> I guess recirculating crankcase gasses is an option, but I don't  see it 
> as a
> requirement.  A catch-can is an OK solution, but if you use  the car
> aggressively, it will fill fast.
> Even an AAN engine, with its  windage tray, will push a very large amount 
> of
> oil through the breather system  during an aggressive launch.  No good.
> I don't know if I'd want to  make a project out of properly sizing the
> breather system.  To me, a good  solution involves a breather device that 
> allows the
> oil to return to the  crankcase.
> If you've built an engine with serious performance potential  in mind, no
> matter how good the system works, you're going to be pushing a lot  of oil
> through it... not just gasses.  To me it was only important to  properly 
> vent the
> crankcase, and return the out of control oil flow back to  where it 
> belongs...
> the pan.
> Unless you redesign around some of the  limitations inherent in the stock 
> oil
> supply system, I think that a PCV  approach will always leave you with oil 
> in
> places that you don't want it...  FWIW.
> Dave
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