[teoman]

Yes it could be possible to win in fuel efficinecy. But i like to fully understand what is going on. Then i feel that i can tune it so that i can maximise the benefit.

Unfortunately that energy is not useless waste energy. Its function is to heat up the air and make it expand.

But with the water phase change if you can get the same gas pressure but cooler, you have less losses.

For example how much water is ideal?

For 20 units of water to 1 unit of fuel by mass theoretically you are producing steam at ambient pressure. So the engine will not run.

All the academic publications i have read seem to suggest that %20 water to fuel is the most beneficial.

But those are lab tests. And in real world consitions with changing load and rpm ine may need different rates.

If i can understand the theory behind the anectodal evidence i believe i can create the best setup.