The influence of the burning chamber upon the burning process in DI Diesel engines is well known. That's why, the authors had developed, using the finite element method two new geometries for the burning chamber, optimized from the point of view of the energy of the fresh inlet charge into the chamber and from the point of view of swirl ratio into the cylinder. This paper shows how the geometry of the burning chamber may change the ratio of the exhaust gas at a DI Diesel engine.