Hi Paul, just got this from Garrett,
http://tinyurl.com/3fmh5co

Murry I. Rozansky

http://en.wikipedia.org/wiki/Thermosiphon

It is interesting that the stock Mazda 2nd gen turbo cooling
system violated some of the Garrett rules on water cooling.

In an aircraft the situation is modified by the fact that
one must land. In the process of landing and taxiing to tie down
the power is cut way back for a considerable time so the turbo
has a chance to cool off. One can buy a device for your turbo charged
car that idles the enginbe for five minutes after the ignition key
is turned off. They are sometimes called turbo timers.

http://www.ehow.com/about_6388058_turbo-timer-information.html

Heat soak is less of a problem in an aircraft application. Also if
synthetic oil is used in the engine instead of mineral oil the synthetic
oil is less likely to coke in the turbo charger after shutdown.

A third factor is the use of silicon nitride ceramic ball bearing that
can take twice the heat of steel ball bearings.

A more important factor is the turbine blade temperature
which should be kept as low as possible during take off and
cruise for blade strength reasons.


Paul Lamar