Based on a heavy duty diesel engine

a numerical simulation study of the scheme which could move the minimum fuel consumption range to different conditions by matching different combustion systems was carried out. Results show that when the compression ratio was 19.5

the distribution of the lean mixture in the cylinder was reduced

and the heat release rate was faster

resulting in a higher thermal efficiency. The minimum brake specific fuel consumption(BSFC) range could be moved to various target conditions by matching turbocharger and combustion chamber appropriately. When the compression ratio was increased to 19.5

combined with turbocharger configurations optimized at low speed

the minimum BSFC range could be moved to low speed condition

with BSFC upmost reduction of 3.1%. When the compression ratio was increased to 18.5

together with turbocharger optimization

the minimum BSFC range could be moved to medium speed condition

with BSFC reduction of 1.6%. Similar approach was applied at high speed and high load with elevated peak in cylinder pressure limit

within which a relatively larger turbine was adopted and the compression ratio was increased to 21.5

and the BSFC at high speed and high load could be reduced by 4.2%.