Turbo 101

["P-O Selander (EUS)" <EUSPOS@am1.ericsson.se>]

Chip wrote:
> Want to learn a little more about the 1.8T I am about to order.  I have
> read a little about letting the turbo cool down after hard driving. Could
> someone please explain further?
> 
I write:
Chip, you will get lots of good suggestions from current A4 owners and my
experiences are from Saab turbos and my present Nissan 300ZX Twin Turbo, so
see them more in a generic light.

I always let my turbo run on idle for a while to make sure that I have good
lubrication (oil pressure and "somewhat" heated oil) before taking off. Also
checking my oil pressure gauge once in a while to verify "normal" and
consistent behavior. Prior to shutting down the engine, I always let idle in
order for the turbos to cool down.

In older cars (early Saab Turbo and I think also Audis) there were
frequently problems wit the turbos (oil leakages and bad bearing, clogged
lines). Many times the turbos were not water-cooled and once shut off, they
"baked" the oil inside due to extreme heat (and no oil circulation),
clogging the oil lines. This was later taken care of by in some cases having
the water evaporate in the turbos (having water go from liquid to steam
requires tons of energy) and thereby providing cooling. Some cars have a
pump that continues to pump the coolant around even after the engine is shut
down, some cars pumps the oil around after shutoff, some even before.

Many will tell you that you definitely need synthetic oil. I have not (yet)
been running it but will change in my Nissan once the summers here and the
car is out of the garage (hasn't been started in over 3 months). There's
probably just pros for running synthetic, maybe with the exception for the
price (which is still VERY low compared to new hardware). Lots of info on
this in the archives.

I think the basic for longevity in a turbo car is proper driver behavior.
Let it warm up gently and let it cool down gently. Since turbos today have
gotten pretty "civilized" (no turbolag etc) and are found in more and more
"normal" cars, many people tend to forget that there's a little hot turbine
up front and that it requires at least some attention.

P-O Selander, Bellevue, WA
89 100E
91 300 ZXTT