Analysis of the Effect of G95M5 Fuel Mixture on Engine Vibration Characteristics at Various Operating Speeds

Abstract

This study analyzes the effect of using a G95M5 fuel mixture (95% gasoline + 5% methanol) on engine vibration characteristics at various operating speeds. The analysis was carried out in the frequency and time domains to identify changes in vibration patterns due to fuel variations. Tests were carried out at 1000 rpm and 1500 rpm, with an acceleration sensor used to measure vibration amplitude. The frequency spectrum results show that at 1000 rpm, G100 fuel (100% gasoline) produces a higher vibration acceleration peak of around 0.030 m/s², while G95M5 only reaches 0.005 m/s², indicating that methanol helps dampen vibrations at low speeds. However, at 1500 rpm, there is an increase in vibration acceleration in G95M5, with a maximum peak reaching 0.07 m/s², compared to G100, which is only 0.035 m/s². Time domain analysis shows the same trend: at 1000 rpm, G95M5 has a maximum vibration amplitude of ±0.006 m/s², lower than G100, which reaches ±0.028 m/s². Conversely, at 1500 rpm, the vibration amplitude of G95M5 increases to ±0.065 m/s², greater than G100, which is only ±0.04 m/s². These results indicate that methanol in the fuel mixture can dampen vibration at low speeds but increase vibration intensity at high speeds. Therefore, methanol content optimisation is needed to balance combustion efficiency and engine mechanical stability.