Fig. 5 (a) above demonstrates that the amount of trapped water increases for the “II” position. Concerning phasing, 250°CA seems to be the best solution, since trapped water decreases for more advanced and more delayed SOI values. Case named 250-II provides therefore the greatest amount of vaporized water in the chamber, thus allowing the charge to reach the lowest temperature at the end of the compression stroke. Thanks to the reduction of the injected fuel request, fuel injection timing is also investigated by comparing two phasing: the first keeping the same SOI, while the second keeping the same EOI as the original case. λ distributions at the spark time show that the equal EOI case is characterized by a better fuel stratification, resulting in leaner end gases (to increase knock resistance) and slightly richer λ near the spark plug (to promote flame kernel development).It also results in reduced fuel backflow in the intake port.