[user removed]

Take an acetylene torch and move your finger past the flame very quickly. Not really but I have done that a few times, mostly accidentally. Since your body is 90% water if water could be Instantaneously vaporized, your finger would evaporate in the heat. In a running engine that is happening much faster than you could ever move your finger past a torch flame.
It takes a lot of heat to get steam superheated, the state where it really produces power. Magnitudes of more heat than to jsut bring it to a boil.
In 760 degrees of crankshaft revolution you may see that kind of temperature for less than 45 of 750 degrees.
Now an oxygen sensor needs considerable heat to function properly. How are you going to make steam without cooling the exhaust to the point where the O2 sensor is not functioning.

regards
Mech