Keywords: Fuel, Specific Fuel Consumption, Octane Booster additive PENDAHULUANBerkembangnya teknologi otomotif saat ini menjadikan teknologi kendaraan juga semakin berkembang. Termasuk dalam perkembangan ini adalah pada sistem pembakaran yang memiliki tingkat kompresi rasio yang tinggi sehingga memerlukan jenis bahan bakar yang sesuai agar pembakaran berjalan dengan sempurna. Proses pembakaran tersebut akan mempengaruhi kinerja mesin secara keseluruhan dan efisiensi pembakaran pada mesin itu sendiri (Li et.al., 2017). Selain itu, dapat terjadi knocking yang diakibatkan oleh proses pembakaran yang tidak sempurna di dalam ruang bakar pada mesin (Zhi et.al., 2017) (Sugiarto et.al., 2007).Saat ini, para produsen kendaraan bermotor mendesain produknya agar lebih mudah dalam hal perawatan. Dengan kondisi mesin yang sudah modern dan sistem kendaraan yang lebih canggih, perawatan kendaraan bermotor tidak lagi diharuskan dengan membongkar pasang komponen-komponen yang ada seperti perawatan saluran bahan bakar (Hu et.al., 2017) (Nur, 2016) (Xing-cai et.al., 2005).Para pengguna kendaraan bermotor dapat melakukan tindakan perawatan preventive terhadap saluran bahan bakarnya sendiri yaitu dengan menjaga kualitas dari bahan bakar yang dipakai salah satunya dengan penambahan zat aditif pada bahan bakar. Ada beberapa zat aditif yang bisa ditambahkan ke dalam bahan bakar, dimana mempunyai fungsi sama yaitu meningkatkan kinerja dari mesin kendaraan (Alptekin, 2017) (Saputra et.al., 2013).

Turbines convert the kinetic energy of ocean currents into electrical energy produced by the sea current electric power plant. This study aims to design a power generator turbine modeling that is carried out using the Computational Fluid Dynamic (CFD) approach by comparing the geometric performance based on the angle of attack and the Tip Speed Ratio (TSR) value of the Savonius-Darrieus Turbine. Having done several trials and errors during collecting the data, the value of the TSR 1.427; 2.853; 4.28; 5; and 5.7 is proposed. Here, the NACA 0018 series has been adopted on the current design of Savonius-Darrieus Turbine. The turbine has three blades, length of the span 357 mm, the diameter of turbine 428 mm, and length of the hydrofoil chord 40 mm. Effect of various angle of attacks from 0°up to 10° has been taken into account in the computational to obtain the coefficient power for each variation. The results revealed that the turbine with an angle of attack of 5°and TSR value of 5.0 has higher power coefficient value by 0.469 as compared with its angle of attack of 10°. It should be noted here that the increase of the angle of attack up to 10° resulted in a significant reduction of the power coefficient value of 0.206 as the value of TSR about 4.28. The addition of the Savonius Rotor results in increasing efficiency of the turbine for sea current applications.

<em>Mechanical contact is the process which can not be avoided in machinery system. The way to diminish thrist conditon which caused by the process is to give engine lubricant into that system. The lubricant resistance over the temperature system is influenced by base stock and its additives where contained of. Lubricant oil additives are chemical compounds that will improve or enhance the lubricant performance of base oil. These additives are carefully designed to ensure the functions in machines system. Engine lubricant that used in this research is MPX 1 SAE 10 W-30 and the additives that used is Engine Additive with brand Lupromax. The aim of this research is to analyze the reaction of increasing the additive EA over to viscosity and machine function of Honda All New CB 150R. In this research, it is found that the fusion with EA 5.25% (1200 ml lubricant with 63 ml additives) could: (1) reduce viscosity to 66.56 mm²/s and 9.9 mm²/s at temperatures of 40°C and 100°C, respectively, (2) enhance the torque and energy to 14.5 kW @9000 rpm and 12.23 Nm @7000 rpm with reducing the rate emision of CO to 0.44% vol, HC to 196 ppm vol, CO₂ to 6.5% vol and enhancing the rate of O₂ to 10.71%, and (3) reduce fuel consumption to 18.75 ml/km.</em>

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The ideal room temperature will create comfort in the learning and teaching process. With increasing outdoor air temperature due to climate change, an air conditioner is needed to reach the ideal room temperature. An air conditioner is an air conditioner that is needed to regulate the temperature and humidity of the air in a room. The purpose of this study is to determine the airflow pattern produced by air conditioning equipment and to determine the distribution of air temperature in the computer laboratory room. Computational Fluid Dynamic (CFD) is a simulation method used by using the ANSYS application. Based on research conducted in a computer laboratory room which has a length of 12 m, a width of 12 m, a chamfer of 3.93 m and a height of 3 m, the airflow pattern produced by the air conditioner is relatively the same between the variable air velocity 2.5 m / s and 3 m / s. Where the air will move straight in accordance with the outlet shape of the air conditioner and then experience a decrease in speed over a certain distance and a change in the direction of air flow occurs due to exposure to room properties and eventually spreads throughout the room. The average temperature in the computer laboratory room for the variable air velocity 2.5 m/s is 24 ° C. Meanwhile, the variable air velocity 3 m/s 23 ° C.