I understand Steve. I had this idea myself some while ago, however studying more i noticed that is serious violation of the conservation of energy...
Actually many thought in the past that when water gas explode it becomes liquid water again, forming vacuum as result, actually its not true. The h2 and 02 liberates heat than it forms a super heated dry steam, that heats up the air and water vapor (humidity) to cause the pressure that pull down the piston. The heat derived from the combustion creates the extra pressure.
I thought this in the past if you add some right amount of vapor and pure H2 O2 or a mixture with some air, than all the energy of the gas will be transformed into pressure... Actually the vapor must be injected at a temperature where it becomes liquid under the compression pressure so it takes "little" energy to expand 1800 times.
So you need heat and H2 O2... I published in the past somewhere, and later abandoned the idea... The problems is that under pressure the temperature required for this vapor to expand is greater than 100°C so you need to generate the vapor and heat it somehow before injection.
Than the heat it must absorb to expand is given by the combustion of a certain amount of H2 O2.. .how much?
Well reason tell me that the heat must not be enough to make it detonates... The fact is that when the engine finish the compression cycle and the vapor get liquified by the compression, it than rapidly absorbs the energy from the combustion while still remaining liquid, when the pressure starts to drop due to the engine keep turning, the water get expand while pulling down the piston.
well it seems great!
However notice how first the vapor got to become liquid by compression!
The benefit to it might be that water might be able to absorb the energy more rapidly... And thus this phase transition will provide the pull force and not the heat expanding the gas... with "no" phase change...
If we had enough energy we could do this. Anyway If we had enough energy we could run it electrically.... Or with soap bubbles if we wanted.
When gasoline is burned a big amount of water vapor is formed.
I'm not sure if it will or not work but this is my analysis of it...
Many ideas is nice as you first think of it, later analyzing the problems start to arise.
