Chemical reaction (from Supra)

[A70Duster at aol.com]

If you were to ignite fuel and air (C8H18 + 12.5 O2 >>> 8 CO2 + 9 H20) with 
no addition of heat from the reaction, you would get a 36% increase in 
pressure.  With ignition (assume 1600°F temp increase after combustion, 
PV=nRT, and 80°F init temp) an increase in pressure of 380% from addition of 
heat.  THIS IS JUST BALL PARKISH!!!!!

The idea Otto cycle is (during combustion) a pressure increase.  Add water 
during this pressure and heat is taken away so less pressure against the 
piston.  Some pressure is gained from the vaporization of water, but I 
"guess" that would not make up for the heat loss/pressure decrease.

See ya,

Mike