Abstract <p>A mathematical model for the calculation of the combustion process in a gas engine with the prechamber ignition is developed. A new approach for modeling the prechamber ignition is proposed. The jet of hot burnt gases is modeled as a set of movable heat-generating particles. The calculation of the flame propagation in the main chamber is based on solving equations for the turbulent transport of the impulse, energy, and components of the gas mixture. The system of the transport equations is solved numerically on the base of the control volume method, applying staggered grids for components of the velocity vector and scalar variables. The model can be applied to optimize the parameters of the prechamber ignition to achieve the best stability and efficiency of the combustion process.</p>