The paper is focused on simulation of high-pressure part of thermodynamic cycle in a four-stroke spark ignition engine. The main author's ambition is to create the fast and sufficiently accurate multi-zone simulating tool working on the basis of simple quasi-dimensional method reflecting a real 3-D combustion chamber geometry and using the specific approach to transfer and transformation of species. The introduced procedure combines a classical kinetic scheme with the flexible Holub's method for chemical equilibrium to solve serious numerical issues resulting from chemical kinetics itself. But for the present, the current version model uses just fast chemical kinetics with direct transformation of reactants to chemical equilibrium state. New code is able to work in predictive or inverse mode as well.Real 3-D combustion chamber geometry is taken into account by means of in advance created geometrical characteristics to save a computational time during the simulation. New tool, developed in AutoLisp programming language environment, can be used for evaluation of data tables with particular zone volumes and combustion chamber total volume, areas of border surfaces between zones and heat transfer areas between particular zones and parts creating combustion chamber border.The predictive model version is suitable for the usage inside the environment of early-stage engine development systems, linking the combustion chamber geometry with the rate of heat release prediction, nitrogen oxides emissions and the future prediction of knocking resistance. The boundary conditions for a preliminary design of combustion chamber components and other combustion chamber features are determined as well. Selected three-zone model results concerning spark ignition version of AVIA engine are presented here.The inverse model version is to be combined with experimental data to determine or verify the important fuel properties, namely the turbulent flame velocity. In this case, one two-zone model output using measured data from ŠKODA engine is presented.