[s-cars] RE: oil and turbos > CCV 201

[Kaklikian, Gary]

Well, didn't intend to hijack this thread, especially regarding a non-S-car, and I realize there are several related issues involved. As I mentioned in my original post:

"At this point I'm not sure whether the problem is high crankcase pressure, excessive blowby from worn piston rings, the turbo seals, or an inherent flaw in the design of the oil drainage from the air/oil separator and turbo on this particular motor, all except the last of which would be applicable to the Audi 20vt motor as well."

So I agree with you Scott, that at least in my case, there may be problem with oil return from the crankcase vent system (separator in my case) and turbo, and that remedies such as a restrictor in the turbo oil feed and an oil cap filler vent are only bandaids. And you are 100% correct about aeration of the oil and high oil temps, known problems with the 944T on the track (as well as rod bearing starvation). I do have a second oil cooler on the car, and although there is no oil temp gauge, the oil pressures stay higher on the track, and the vendor's tests show drops of 50F in oil temps. 

When I have a spare $10G, I'll rebuild the motor correctly with a dry sump system, air/oil separator, etc. For now... first off is the oil filler vent cap and Lucas oil stabilizer, and then possibly the restrictor in the turbo oil feed line.


-----Original Message-----
From: QSHIPQ at aol.com [mailto:QSHIPQ at aol.com]
Sent: Tuesday, December 09, 2003 09:15
To: Kaklikian, Gary; s-car-list at audifans.com
Subject: Re: oil and turbos > CCV 201


I don't believe in any stabilizers, I'd rather address the design of the 
system that makes you feel the need for it.  You have identified and moved the CCV 
discussion to a related topic (tangental, but certainly relevent) of 
different turbos on a given application and oil management in a more general sense.  
One of the issues which can lead to increase CCV is not so much the oil feed, 
but more the oil return.  The turbo oil return line size is important in 
designing a oil crankcase feedback loop that is of the least amount of aeration.  I 
might venture to propose that if a higher (different) feed pressure and flow 
is used on a larger turbo, a larger feedback to the pan might be dictated.  The 
more pressure the feedback to the pan is under from a turbo, the higher the 
aeration of the oil in the crankcase.  Think of this as spraying water into a 
bucket, but the release of aeration isn't so immediate.  Aeration of oil is 
extremely critical in the consumption of oil in extreme use enviornments.  
Especially oil that has just passed thru a 1600degree heater core while performing 
track duty.

I'd also suggest Gary (if you already haven't done so) putting on as big an 
oil cooler as you can fit on the car.  Part of the "viscosity and thermal 
breakdown" characteristics in oil is exactly because of aeration>saturation as oil 
temps exceed the ideal temp (I consider oil ideal temp to be 100c)/viscosity 
index.

IMO, those tweeking S-cars into any significant number should minimally read 
SAE 970922 (Development of Modern Engine Lubrication Systems), since it 
applies directly to the I5 and audis "philosophy" on oiling systems.  It can help 
you as well Gary, since it speaks of the pressure/aeration/saturation issues of 
oil in a general design sense as well.

No question in my mind that highly modified cars have to be micromanaged in 
their systems and modified application (read: turbo) with regard to the 
lifeblood of the motor = oil.  CCV and PCV modifications and application really are 
part of oil management, and should never be considered an afterthought.  This 
stuff is nothing new, and the problems with it now aren't any different.  The 
available catchcans may exceed my choice of plumbing fittings applied to a 
drilled out chicken broth can I remember on my first SB back in the 70's, but the 
reason for it is the same.

HTH

Scott "nerdman" Justusson
QSHIPQ Performance Tuning


In a message dated 12/9/2003 9:40:25 AM Central Standard Time, 
gary.kaklikian at hp.com writes:
Yeah, I'm going to try the oil filler cap vent and Lucas Oil Stabilizer 
first, although several 944t tuners suggest the oil feed restrictor with Garrett 
turbos. No smoke out the exhaust, but the intercooler pipes are full of oil.  I 
don't doubt there's a problem with the oil rings,  but compression is good and 
leak down was under 10% on all cylinders. And oil consumption is only really 
excessive on the track.  
Any thoughts on using Lucas Oil Stabilizer, with synthetic or dino juice?