The limit of IC engine efficiency cannot be normally exceeded due to facts entropy cannot be decreased and 2nd law of thermodynamics (heat cannot flow from cold to hot body). Injecting water in the beginning of expansion stroke can overcome these problems since entropy of working fluid (hot gas) will be decreased when water’s entropy is increased while converting it to steam but as a whole (water and gas) the entropy will be slightly increased or remain same. The temperature of exhaust gases too will be lowered since water too has to be heated, this heating of water to steam will result in higher pressure thereby resulting in more work.
In normal engines there is only one source (fuel) and one medium (Air) of finite masses. In this during expansion temperature of both become same then temperature can no longer lowered without heat transfer to the surrounding or by expanding, but expansion has a limit.
In Anyoon engine there are two mediums (Air & Water)and one source(fuel) with total mass equal to mass of source +and air in normal engines + mass of water. Water is injected in expansion stroke only. So water can lower the temperature of medium lower than in normal engines since source (of same mass of fuel) also has to heat up the mass of water. So average temperature will be lower in Anyoon engine than in normal engines; even with same expansion ratio and adiabatic conditions. The result of this heat transfer is phase change of water and then expansion of steam (or more work).