Abstract
It was the intention of a research programme, developed together by S.C. MASTER S.A. and S.C.CESAR Campulung, to identify the potential and to find out the solutions of increasing the power output and reducing the smoke level in case of the natural aspirated diesel engine ARO L27 D.
A very interesting part of the programme was the improving of combustion process inside this IDI type engine, mainly by constructive and functional modifications of both separate and in piston combustion chambers. The paper presents the most important aspects related to the mathematical modelling of specifically processes, as definition base of the new combustion chamber geometry, and some significant results obtained by implementation of these modification.