A LPG fuelled, spark ignition engine for heavy duty vehicles has been developed from a Diesel DI engine which is currently in production. The development concept was based on the targets of obtaining output performances by LPG fuelling comparable with those of the original Diesel engine under full load conditions to be achieved with relatively simple technologies. A conventional mixer system with closed-loop control was consequently used for the LPG fuel supply system, operating at λ = 1.0.
A systematic optimization was applied in the areas of the compression ratio, combustion chamber configuration, intake swirl ratio and plenum configuration, spark timing, in view of reaching high output performances and knock phenomena control.
