Direct fuel injection is becoming mandatory for two-stroke S.I. engines, since it allows using only air in the scavenging process, preventing fuel loss from the exhaust port.
However, also combustion irregularity at light loads is a problem of these engines, due to excessive presence of residual gas in the charge. For its solution, additional strategies must be adopted. The two most suitable ones are charge stratification and ATAC (Active Thermo Atmosphere Combustion), which makes use of residual gas energy to ignite fresh gas, turning the effect of residual gas from negative to positive.
In previous papers, the possibility of combining ATAC with different injection systems was proved.
This paper provides further insight on ATAC combined with liquid high-pressure direct injection and shows the studies and the first experimental results relative to charge stratification.