[s-cars] Oil and Turbos

[Tom Green]

>
I don't think in Manny's case that the bearing housing temperature is  
120ºC given his oil temp is already 150ºC at the pump.  I don't  
dispute the
Audi relative measurement of temperatures, but they must not have had  
150ºC oil going into the turbo.

Manny has hinted at one issue, the oil cooler airflow is almost  
totally blocked by the FMIC piping.  Airflow is needed for whatever  
oil cooler is in
the system, so probably a fix there will show results if oil is  
flowing through the cooler.

> -----Original Message-----
> Date: Tue, 24 Mar 2009 23:15:00 -0400
> From: djdawson2 at aol.com
> Subject: Re: [s-cars] Oil and Turbos
> To: qshipq at aol.com, trgreen at comcast.net
> Cc: manuelsanchez at starpower.net, s-car-list at audifans.com
> Message-ID: <8CB7B0F04244288-1564-26DC at WEBMAIL-MC21.sysops.aol.com>
> Content-Type: text/plain; charset="utf-8"
>
>
> Interesting info...
>
> It seems almost hard to believe that you can get the hot side of a  
> turbo glowing red, yet the bearing temp only sees 120C.
>
> It still seems to me that the turbo is where oil failure is most  
> likely to occur, just based on years of history looking at coked/ 
> plugged oil return lines.? I don't dispute the facts you've  
> presented, it just seems to be a more frequent point of failure...  
> one way or the other.
>
> It's tough to read chat on the list about substituting an elbow in  
> place of the after-run pump... bad choice of solution for anything  
> other than getting home.
>
> -----Original Message-----
> From: Scott Justusson <qshipq at aol.com>
> To: 'Tom Green' <trgreen at comcast.net>; djdawson2 at aol.com
> Cc: manuelsanchez at starpower.net; s-car-list at audifans.com
> Sent: Tue, 24 Mar 2009 8:44 pm
> Subject: RE: Oil and Turbo
>
>
> Audi wrote the book on all this turbo/oil stuff, specifically
> co/authored many SAE papers on the subject, before and after  
> watercooled
> turbos/synthetic oils. Specific to this topic ---  See 880258 "The
> development of a Severe Turbocharger Bench Engine Test" and 860103  
> "The
> third-Generation Turbocharged Engine for the Audi 5000 CS and 5000CS
> Quattro", and 970922 "Development of Modern Engine Lubrication  
> Systems".
>
> Relevant Info to this thread:
>
> 860103 - Running I5 turbo motor, the temps of the piston ring with
> watercooling are 190C, temps of the turbo bearing housing 120C.
> Shutdown kills engines if the water circulation circuit is not
> functioning.  Without w
> ater cooling the numbers are 260C PR and 140C
> TBH.  On shut down, the non water cooled temps go to 360C PR and  
> 250TBH
> within 2 minutes of heat soak.
>
> Rule:  Make sure your after run pump is working.  Regardless, some
> idling before shutdown never hurts.
>
> Manny, leakdown of </=10% is good, =/>20% is bad.  Do compression  
> check
> first.  IME, the 25 row oil cooler is a good match for the I5 20vt.   
> At
> 90+F track day running an S car hard with a 25 row cooler, I  
> observed a
> peak of 120C, and by the time we got to back into the pits the temp  
> was
> at or under 100C.  For a dedicated track car a 36 row is better, but
> overkill (read tough to get up to 100C) for daily driving.  Altitude  
> and
> an FMIC, might be better with the 36 row, but that's a big dog to  
> stuff
> under the hood of the dog house.
>
> Specific to the concerns on oil temps in other cars, the rule of thumb
> is you want the oil temp to reach 100C to burn off the moisture in the
> oil.  Since all Audi turbo cars come with 100C oil cooler thermostats
> from the factory, this should be a non issue on the AAN.
>
> HTH and my .02
>
> Scott J
>
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] On Behalf Of Tom Green
> Sent: Tuesday, March 24, 2009 7:15 PM
> To: djdawson2 at aol.com
> Cc: manuelsanchez at starpower.net; s-car-list at audifans.com
> Subject: Re: [s-cars] Oil Temperature
>
> I just know better than to touch any of this stuff when it's hot.
> But, I am sure that the
> oil temps are high enough to coke conventional
> oil at 150?C, and at that inlet temperature, it would be hotter in the
> turbo.  What was engineered to work just fine for 50K miles is
> not necessarily just fine at 150K miles.  The advantages of synthetic
> are proven for the turbo applications, which is what I wanted to
> convey.
>
> I think Manny's OEM cooler can keep up with the RS2 if it is in good
> condition.  Most I see have coils almost filled with oily dirt on the
> outside.  Insides can be nasty also, so I would check the present oil
> cooler out before opting to buy an aftermarket system.  Perhaps
> he needs a bigger cooler.  I certainly don't want to suggest that
> Manny needs to "back off" on any of his sessions.  : > )
>
> Tom
>
> On Mar 24, 2009, at 6:44 PM, djdawson2 at aol.com wrote:
>
>> I think the bearing section of the turbo is, without question, the
>> place where oil temps are highest... hence the after-cooling pump.
>>
>>
>> -----Original Message-----
>> From: Brett Dikeman <brett.dikeman at gmail.com>
>> To: Tom Green <trgreen at comcast.net>
>> Cc: Manuel Sanchez <manuelsanchez at starpower.net>; Scarlist
> <s-car-list at audifans.com
>>>
>> Sent: Tue, 24 Mar 2009 2:29 pm
>> Subject: Re: [s-cars] Oil Temperature
>>
>> On Tue, Mar 24, 2009 at 3:36 PM, Tom Green <trgreen at comcast.net>
>> wrote:
>>
>>
>>
>>> At the turbo, the oil probably reaches the flash point, so that
>> can't be good.
>>
>>
>>
>> I'm not sure what the relevance of flash points are, but the flash
>> =0
> A> point of 15w50 Mobil1 is 235C; 455F.  The coke point of most
>>
>> synthetics is even higher.  In a water-cooled-center-section k24, you
>>
>> think the oil is heated by a differential of more than 100C from the
>>
>> coolant?  These cars were designed to work just fine on dino oil...
>>
>>
>>
>> One would think oil sees the hottest surfaces around the
>>
>> pistons/rings/cylinder wall.
>>
>>
>>
>> Brett