Study of Four-Stroke Engine Vibrations: Influence of Friction and Thermal Effects on Piston Speed, Displacement, and Acceleration

This paper presents an analysis of vibrational influences on the stability of four-stroke IC engines (Internal Combustion(, by comparing different engine types to determine the engines most sensitive to increased values of vibrations. Emphasis is given to single-cylinder engines in particular to a popular motorcycle engine that was found to generate the highest vibration levels ever obtained. Vibration measurements were made at engine points on the engine for experimental evaluation of the stability and dynamics of the engine under varied operating conditions. Analog accelerometer modules were integrated into the engine and tied to an Arduino-based control system that allowed to get on the spot results whenever wanted. A modal analysis using MATLAB was conducted to study the effects of connecting rod length on essential performance characteristics based on acceleration, velocity and displacement. The results show that using longer rods results in lower levels of vibrations, which illustrates that rod length is an important parameter in relation to the vibration properties. This study provides valuable insights into vibration mitigation strategies aimed at enhancing the reliability, efficiency, and overall performance of internal combustion engines. The highest vibration at low acceleration was recorded at 1500 rpm with a value of 16 mm/s², while the highest vibration at high acceleration occurred at 1900 rpm, reaching 33.4 mm/s². Numerical analysis of the slider-crank mechanism dynamics (r = 26 mm, L = 130 mm) using MATLAB shows that friction reduces velocity, acceleration, and displacement by 15% across all rod lengths. Additionally, temperature effects reduce acceleration by 8.5%, and the combined influence of friction and temperature leads to a 22% reduction in velocity, acceleration, and displacement. In comparison to other engines, the Toyota 6-cylinder engine is among the most dependable, low-vibration, and long-lasting. The Toyota 2500 and BOXER 150CC engines displayed the lowest vibrations (1.4 mm/s2 at 800 rpm), suggesting exceptional stability.