Ahmad Faizal et al., International Journal of Emerging Trends in Engineering Research, 9(4), April 2021, 361 – 366 361 ABSTRACT Air-cooled motorcycle engines release heat into the atmosphere through the process of forced convection, an important component for increasing the convection heat coefficient and the rate of heat transfer is fins. The rate of heat transfer depends on the geometry of the fin, the surface of the fin, the thickness of the fin, the distance between the fins, the temperature of the environment, and the air velocity. The research was conducted by varying the air velocity with the addition of holes in the geometry of convex fins. The main purpose of this study was to analyze the rate of heat transfer that occurs in the geometry of perforated fins by varying the air velocity. Physical models are designed using the Autodesk Inventor Professional 2020 application and simulated by Dynamics 2019 Autodesk Computational Fluid. The result of 4mm perforated convex geometry analysis is better than 2mm and 6mm perforated fins and non-perforated. Due to this, the rate of heat transfer has increased so that the coefficient of convection heat transfer increases and the decrease in the temperature of perforated fins is consistently higher than non-perforated fins, improving the efficiency and effectiveness of motorcycle fins so that the performance of motorcycle engines also increases indicated by the temperature distribution. Key words: Air velocity, Heat transfer, Motorcycle fins, CFD. 1. INTRODUCTION Transportation is increasing as the population grows and people's needs for transportation are fast and easy. One of the means of transportation that can help is motor vehicles [1]. Motor vehicles with internal combustion engines to generate energy perform the combustion process. The combustion process was continuous in the engine resulting in overheating. This requires a detailed study to cool the machine at an ideal working temperature with a cooling system. Fins are an important component for increasing the coefficient of convection heat and the rate at which heat transfer releases heat into the atmosphere through forced convection. The rate of heat transfer depends on wind speed, geometry, surface area, and ambient temperature. The main objective in this study was to increase the rate of heat transfer geometry of convex shape fins adding holes 2mm, 4mm, 6mm, and varying wind speed to improve the performance of motorcycle fin engines carried out a computerized approach using Computational Fluid Dynamics (CFD) software. There is a lot of literature that discusses heat transfer with forced convection mode on motorcycle fins. Based on research [2] conducted experimentally and simulated on a Honda 100cc Motorcycle to analyze thermal properties by varying the geometry, material, and thickness of cylinder fins. The geometric shapes of the fins are rectangular models created by varying geometric shapes such as circular and curved and the thickness of standard fins is 3mm, reduced the thickness of the fins to 2.5 mm on each geometric shape. The 204 alloy aluminum material that has 110-150 W/m•k thermal conductivity in this test is varied with aluminum alloy 6061 and magnesium which has high thermal conductivity. For its simulation testing, pro/ENGINEER software is used on 3D modeling, and analysis is performed using ANSYS. By varying geometric shapes and reducing their thickness and varying materials, the fin's weight is reduced, improving its effectiveness and efficiency. The thermal analysis obtained in this study was better-curved fin shape than other geometric shapes and Aluminum Alloy 6061 material by reducing fin thickness by 2.5mm better due to higher heat transfer rate. By changing the thickness of the fin and changing the material of the fin geometry shape compared to the machine that has the thickness of the fin and its geometric shape it can increase the rate of heat transfer so that increasing the rate of heat dissipation on the fin will increase the efficiency of the machine. This study [3], was conducted in simulation on a 115cc Bajaj Caliber Motorcycle to analyze thermals by varying the material, slit size and length, and thickness of the fins. The materials used are Aluminum Alloy 204 which has a thermal conductivity of 120 W/m•k varied with Aluminum Analysis of Temperature Distribution And Performance of Motorcycle Engine Fins Ahmad Faizal 1 , Slamet Wahyudi 2 , Femiana Gapsari 3 1 University of Brawijaya, Indonesia, ahmatfaizal@ymail.com 2 University of Brawijaya, Indonesia, slamet_w72@ub.ac.id 3 University of Brawijaya, Indonesia, memi_kencrut@ub.ac.id ISSN 2347 - 3983 Volume 9. No. 4, April 2021 International Journal of Emerging Trends in Engineering Research Available Online at http://www.warse.org/IJETER/static/pdf/file/ijeter04942021.pdf https://doi.org/10.30534/ijeter/2021/04942021