This paper presents the results of an analytical study for optimisation of the full-load operation of a compression ignition internal combustion engine with common rail fuel system. The model is made with the aid of the software simulation package Advanced Simulation Tools by AVL List GmbH. An existing engine is used as a prototype of the model – a PSA-manufactured DW10BTED4. The received characteristics from the performance are compared with the manufacturer data. A possible range of model improvements are also presented in the paper.