Kinematic and vibration analysis of a single-cylinder engine: Effects of connecting rod length, fuel type, and engine speed

Abstract This paper emphasizes the role of fuel substitution in mitigating vibrations and enhancing the performance and reliability of internal combustion engines (ICEs). Using MATLAB for modal analysis, the study investigates natural frequencies and identifies potential resonance issues within critical engine components. The primary focus is on analyzing a four-stroke single-cylinder engine under various speeds and measuring the effects of fuel type on engine performance and efficiency. A comparative assessment evaluated vibration levels between natural gas and petrol by measuring engine vibrations across a range of speeds and analyzing the impact of varying dimensions of internal moving components on performance parameters. Results indicate minimal differences between the engines at lower speeds (1,500–2,000 rpm), while significant increases in vibrations were observed at higher speeds (2,500–3,000 rpm) for the gas engine, highlighting potential mechanical instability. At higher speeds, vibrations peak at the top of the engine, reaching 200 m s −2 with petrol and 240 m s −2 with natural gas. The experimental setup, including accelerometer modules and control systems, enabled real-time vibration monitoring. Numerical results showed that the longest connecting rod (197 mm) yielded the highest displacement, velocity, and acceleration metrics. These findings underscore the advantages of using natural gas as a fuel, including its availability, cost-effectiveness, and environmentally friendly nature, as it produces significantly lower harmful emissions compared to petrol. Additionally, the study offers insights into vibration-damping mechanisms and the influence of modifications to internal moving parts, such as crankshaft diameter and connecting rod length, on engine performance and stability.