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Men Van Truong
Nhan Thanh Le
Quang Thanh Le


Nowadays, motorbikes are still the main and most popular transport in Asian countries, especially, in Vietnam. However, the manifold intake systems in motorbikes are usually designed in a simple structure, which can reduce engine performance and increases fuel consumption in motorbikes. This paper presents the study of the improvement of the intake system in a 125cc motorbike engine to enhance air-fuel mixing quality that can increase the engine performance. The study employs the ANSYS software to obtain an optimal intake system
through the tumble and swirl ratios in different simulation cases. Another model was
also built by Matlab/Simulink to examine the effects of swirl and tumble ratios on engine performance and fuel consumption at various engine speeds. The simulation results show that the modified intake system with
an incline angle of 30o has optimal tumble and swirl ratios. Accordingly in conclusion, power output and torque  of the engine with the modified intake system are higher, while  the fuel consumption is lower than previously


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How to Cite
Truong, M., Le, N. and Le, Q. (2021) “THE EFFECTS OF SWIRL AND TUMBLE RATIOS ON THE ENGINE PERFORMANCE OF MOTORBIKES”, The Scientific Journal of Tra Vinh University, 1(39), pp. 91-100. doi: 10.35382/18594816.1.39.2020.572.


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