The purpose of this work is to determine the dependence of the filling factor on the position and burial of the gas supply tube in the inlet manifold of the gas engine. Modeling of gas-dynamic processes occurring during engine intake was carried out by finite element method in the Ansys Fluent engineering analysis software environment. As geometric models for modeling, the part of the engine intake system in which the gas fuel supply tubes were located, which were located in different parts of the intake manifold and had a different amount of burial into the air flow, was considered. Simulations have shown that gas inlet tubes are the source of significant hydraulic losses in the engine inlet system, and as the amount of pipe buria into the inlet manifold cavity increases, these losses increase. Keywords filling ratio, engine intake process modeling, gas engine, hydraulic losses, gas supply elements, intake manifold