Effects of intake fluctuation and chemical reaction on operating stability of a small displacement gasoline engine: An experimental and numerical study

•CCV of a high speed engine was investigated thoroughly by combining experiment and CFD.•The engine load has lesser impact on CCV at higher speed.•Three especial simulated scenarios were designed to isolate factors of intake fluctuation and chemical reaction.•The dispersity and distance from cylinder center of flow motion almost decide the combustion CCV.•Chemical reaction and its interaction with flow filed have greater influence than intake process on CCV.