Humidity, Smokey's vapor engine and other ramblings

[Gary Derian]

     Water injection cools the combustion process by boiling and absorbing
heat during the combustion process, not necessarily cooling the intake
charge.  Best power is obtained when fuel and water (if water injected) is
taken into the cylinder in liquid form.  Liquids take up much less volume
than the same amount of vapor leaving more room for air.  The fuel mixes and
vaporizes during the compression stroke so it is ready to burn (most of it,
anyway).  The water vaporizes during the combustion phase absorbing heat but
not reducing pressure.  This raises the detonation limit which limits power
and efficiency in a spark ignition engine.

    Humidity in the air is already vaporized and only displaces oxygen.

    Smokey's vapor engine attempted to fully vaporize fuel in the intake
system.  This gives better fuel mixture distribution and prevents some
unvaporized liquid fuel from being wasted.  This achieves the same end as
propane fueled engines but propane does not need high temperature to
vaporize.  The tradeoff is reduced power since the fuel, now in vapor form,
takes up some volume in the cylinder so there is less air.  The high octane
rating of propane allows high compression ratios so some power can be gained
back but there still is a power loss.

    Car manufacturers have (1962 turbocharged Oldsmobile 215 V-8) and would
still install water injection if they thought owners would keep the water
reservoir full and not frozen.

Gary Derian <gderian at cybergate.net>