On Sun, 23 Apr 2006 15:25:02 GMT, wrote:

snip
Anything that burns using the oxygen from air produces oxides of nitrogen,
i.e. smog.

There are also the lubricants that are either burned or expelled, but
modern engines have reduced these pollutants to extremely low levels.
The gas engine in my wife's car runs a compression ratio of 13:1, yet
is it listed as one of the lowest emitters of pollutants. Some call
it a zero emitter, but that really means it has met Ca standards.
What I find amazing is how they produce so little Nitrogen oxides with
such a high compression ratio. (It does have variable cam timing) and
the engine even shuts off if not needed. No idle at stop lights or
even going down hill.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

-Elliott Drucker