Date: Fri, 30 Jan 2004 09:08:55 -0500
From: "Fred W." <Fred.Willsnopsampam myrealbox.com>
Subject: Re: Do I need to let my turbo "cool down" for awhile ('1990 C-900T)?
"Grunff" <grunffnopsam.com> wrote in message
news:bvbtma$qil0r$1nopsam52899.news.uni-berlin.de...
> Bob wrote:
>
> > Back to the OP's question: turbo spin-down used to be a more serious
> > issue when turbo units were not water cooled.
>
> The real answer, which I omitted in my previous replies, is this: How
> many of us come off the motorway (US/Can: Highway) and turn off the
> engine straight away? We don't - we drive down progressively smaller,
> slower roads until we reach our destination, by which time the turbo has
> cooled down plenty. :-)
True, however, when you are cruising on the highway in 5th gear, the engine
speed is low and the turbo is not doing a whole lot. OTOH as you blast down
the 2 lane side roads, stopping or slowing at corners and accelerating away
with a crazy turbo induced grin on your face (as in the recent series of
SAAB TV ads) your engine speed and turbo will be spinning up nicely and
heating the housing to the familiar cherry red. The first time I saw this
on my old '92 9000T I was astounded that the housing could become so hot and
yet the turbine bearings continue to work at all!!
I am of the opinion that a minute of idling will actually allow things to
cool down, even more so with the modern water cooled turbos. But, of course,
YMMV...
-Fred W
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