Theory LONG: Audi Warranty issues, AoA was: Car fax

[Cody]

I'm going to have to partially dissagree with that. In my car if I go run it hard for a bit the turbo and header will get glowing a nice red orange in the hotter parts (mostly the collector). It usually takes about 10 minutes of driving too cool it to a decent temp, or 15 minutes of idling. I agree that air cooling effect is there, but not quite as significant as you say. The biggest dissagreement though is where you say that idling is the WRONG thing to do. Maybe it's not the best method, but certainly not the WRONG thing to do. Shutting the car off immediately is the wrong thing to do. What you have to remember is the air cooling effect from the inside out too. If your sitting at idle (or cuising slowly) your EGT's will be so low that your getting a good air cooling effect from the inside out. This is why they sell electronic do-dads that keep your car running after you shut it off and remove the key that eaither are timed to a set ammount, or measure temps and run until i!
t's cooled, that are called turbo-timers in the aftermarket.

-Cody Forbes
Black Forest Racing
http://www.500tq.com
'86 5ktq
'87 5ktq EFI k26/k27
'88 80 4cyl
'88 90 4cyl


---------- Original Message ----------------------------------
From: "Phil Payne" <quattro at isham-research.com>
Date: Wed, 14 Jan 2004 13:59:16 +0100

>> Steve, good point regarding cooling down the turbo. I generally sit in my
>> driveway for about 45 seconds to a minute (depending on the amount of time
>> I have driven the car) and at least wait for the turbo to spool down (I
>> can hear it doing that if I have been driving for a while and/or driving
>> hard) - then wait a bit longer.
>
>EXACTLY the wrong thing to do.
>
>Despite all the crap about oil-cooled turbos and water-cooled turbos, all Audi turbos are
>actually air-cooled.  Oil has almost no cooling effect, and serious water flow through the
>later models' water jackets (only around the bearing) doesn't start until some time after the
>ignition has been switched off.
>
>You need airflow to cool the turbo, and there is no airflow if the car is stationary - except
>the paltry contribution of the alternator fan.
>
>The correct procedure is to drive the last mile or so at the very least without using WoT - a
>steady tootle along is preferable.  When you come to a halt, switch the engine off immediately
>or it will start to heat up again.
>
>And if you mess around with bits and pieces like dump valves, make sure they don't impede the
>airflow to the turbo and exhaust manifold.
>
>--
>  Phil Payne
>  http://www.isham-research.com
>  +44 7785 302 803
>
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