Internal combustion engines have seen a reduction of the dynamics of their efficiency growth in recent years. All kinds of new modifications and changes introduced in this field can only manage changes of engine efficiency at the level of a fraction of a percent. Considering the concept of unification of SI and CI internal combustion engine structures, one can expect to see their efficiency increase by the reduction of losses, whose causes and occurrence is commonly known. The improvement of the combustion system is mainly related to the reduction of thermal losses generated in this process. Therefore, the current issue is the advanced analysis of any possibilities of improving the combustion conditions and more fully understanding the processes that accompany them. The authors of the article see such a possibility in the conceptual control of the combustion process, which aims to obtain a combustible mixture surrounded by nonflammable gases. This way the flame contact with the cylinder walls is limited, which should in turn contribute to reducing the heat exchange with the walls. This research is a continuation of previous research work; current work focuses on determining the actual distribution of gases in the combustion chamber using the advanced shadow photography method. The article specifies the effect of nonflammable gas injection pressure increase on the area of the boundary layer formed between the non-flammable gases and cylinder walls.