The lack of a homogeneous air-fuel mixture in internal combustion engines is a major cause of pollutant emissions, such as carbon monoxide (CO) and hydrocarbons (HC). This paper focuses on the design, simulation, and testing of a modified air intake pipe for a gas engine, incorporating deflectors to induce a swirl effect in the air-fuel mixture. To determine the optimal configuration for the deflectors and the diameter of the air intake pipe, several Computational Fluid Dynamics (CFD) simulations were conducted. The best results were then tested on a real gas engine. The primary objective of this study is to offer a solution for increasing the homogeneity level of the air-fuel mixture in gas engines, without requiring significant changes to engine components. In this case, achieving this goal involves only relatively small modifications to the air intake pipe. The results indicate that the swirl effect effectively enhances the homogeneity of the air-fuel mixture by generating higher turbulence along the air intake path. Critical to the success of the modification is the maintenance of the original pressure drop along the pipe. To compensate for the restriction caused by the deflector in the cross-sectional area of the air intake pipe, it is necessary to increase the diameter of the pipe. The most challenging aspect was achieving a reduction in CO and HC emissions due to the deflectors, rather than solely relying on the increased diameter of the air intake pipe. Importantly, the goal was to maintain engine power without a corresponding increase in fuel consumption. Contrary to the common belief that any device disrupting the free flow through the air intake pipe causes pressure losses, our findings suggest that the right configuration of pipe diameter, along with the appropriate number and positioning of deflectors, can yield better results than maintaining an unrestricted airflow. In summary, our work presents a device intended for implementation in the air intake pipe of gas engines, inducing a swirl in the air-fuel mixture without creating pressure losses compared to the original engine condition. This modification successfully reduces CO and HC levels, serving as an indicator of improved combustion resulting from a more homogeneous air-fuel mixture.