[email protected] (Dave Williams)
fangle  09 Jul 2000

-> > - the temperatures are high
-> > enough to dissociate water into hydrogen and oxygen.

> Does this hold true for a normal gas internal combustion engine?.

Possibly in some very specific places during the combustion cycle, but
overall, no.  The basic process goes to the formation of water during
the cycle.

Gasoline combustion goes through a whole bunch of steps; it's not
nearly so simple as I once thought.  Robert Harris was on a combustion
kick a year or so ago and bent my ear as he was digging back through
some of the basic sources on that sort of thing.

Some of the steps are clearly defined and simple; some overlap, some
can happen more than once, some peter out incomplete, and usually it's
all still going on when the exhaust valve opens and spits it all out.

That's the exact reason Detroit used to claim they could get the same
gas mileage out of a big slow engine as anyone else could get out of a
small high RPM engine.  By keeping RPM down below 3000 or so in normal
operation, there's more time for the cycles to complete.  The difference
is enough to overcome the additional mass, etc. of the larger engine in
most cases.  That's one of the reasons so many new V8 cars are geared
down to 1250-1500 RPM at cruise now; it helps emission controls quite a
bit too.