Original message:
"When I drove my non-turbo diesel in Santa Fe (7200 ft) the air was so
thin power loss was about 1/3 and cold startups in winter were a real
challenge. even if it was turbo that still does nothing for starting in
thin air."
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Here is my diesel vanagon / thin air story:

I drove my turbo diesel westy up to the top rim of Yosemite (10,000 feet
I think) a while back.  It was September and getting cold.  The engine
was getting worn out so it was not in the best shape to begin with. It
would just barely run after I got it started. I could not get the van
started at all unless I disconnected the alternator (unplugged the
field).   When the alternator was connected there was too much load on
the engine and it would not stay running just after you started it.

Gary Lee
Calgary, Canada