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All Journal Otopro Scientific Journal of Mechanical Engineering Kinematika Quantum Teknika Journal of Mechanical Engineering and Applied Technology
Yuris Bahadur Wirawan
Mechanical Engineering In Production And Maintenance Study Program, Politeknik Negeri Semarang, Indonesia
Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Control & Systems Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering

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Investigating Impact of Gasket Cylinder Addition and Octane Rating on Engine Performance Bahtiar Rahmat; Mohammad Burhan Rubai Wijaya; Yuris Bahadur Wirawan; Fahmy Zuhda Bahtiar; Katiko Imamul Muttaqin
Quantum Teknika : Jurnal Teknik Mesin Terapan Vol. 6 No. 1 (2024): October
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/jqt.v6i1.23429

Abstract

The increase in people's mobility were reflected in the growing sales of motor vehicles. This has driven automotive manufacturers to compete in creating more powerful and efficient engines. These engines were designed with high compression ratios to achieve greater efficiency. High compression ratio engine re-quired fuel with the appropriate octane number to attain opti-mal performance. It is regrettable that many users had not un-derstood that an engine with high compression had required gasoline with a high octane rating as well. This research aims to investigate the impact of different compression ratios on the output power and torque of a single-cylinder combustion en-gine using RON 92, RON 95, and RON 100 gasoline. To modify the compression ratio, various numbers of gaskets were used on the cylinder head, with 2 and 3 gaskets for each configuration. A dynamometer test was employed to measure the differences in engine performance. The research results indicate that the engine with the highest compression pressure (11 Kg/cm2) using RON 100 gasoline produced the highest power of 7.90 kW, with the highest torque of 9.60 Nm. Conversely, the engine with the lowest compression pressure (10 Kg/cm2) using RON 92 gasoline produced the lowest power and the lowest torque.
SIFAT MEKANIK DAN FISIK 3D-PRINTED DENTAL PHOTOPOLYMER RESINS DALAM KONDISI PEMROSESAN YANG BERBEDA Ahmad Mamba'udin; Muhammad Akhsin Muflikhun; Adam Zuyyinal Adib; Dianisa Khoirum Sandi; Elfrida Rizky Riadini; Yuris Bahadur Wirawan
Scientific Journal of Mechanical Engineering Kinematika Vol 10 No 2 (2025): SJME Kinematika Desember 2025
Publisher : Mechanical Engineering Department, Faculty of Engineering, Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/sjmekinematika.v10i2.796

Abstract

Photopolymer resins have widely applied in dentistry to fabricate temporary restorations. This work gives a complete characterization of a dental non-castable photopolymer resin prepared via Digital Light Processing (DLP) 3D printing. Specimens were printed at layer thicknesses of 0.05, 0.075, and 0.1 mm, followed by post-cured treatments under UV light for 10, 20, and 30 minutes. A series of material characterization tests were performed, including assessments of hardness, moisture absorption behavior, and density measurements. The results indicate that hardness and moisture content are significantly impacted by post-curing time, while extended curing times resulted in greater specimen’s hardness and decreased moisture content. An increase in layer thickness led to a gradual reduction in hardness. A maximum hardness value of 57.7 Shore D was observed in the 3D-printed specimen, along with a highest moisture content of 1.05% MC. As expected, the specimens exhibited consistent density (1.19 ± 0.02 g/cm³) throughout all layer thickness and curing time variations. This study highlights the critical need to understand how process parameters affect dental non-castable photopolymer resin properties prior to clinical implementation.
EXPERIMENTAL STUDY ON OTTO ENGINE PERFORMANCE WITH VARIATIONS IN COMPRESSION RATIO AND GASOLINE OCTANE Bahtiar Rahmat; Irwan Setyo Prabowo; Yuris Bahadur Wirawan; Fahmy Zuhda Bahtiar
Otopro Vol 21 No 2 May 2026
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/otopro.v21n2.p60-68

Abstract

This research aims to analyze the effect of compression ratio variation and gasoline octane number on the performance of spark-ignition internal combustion engines. The experimental object was a single-cylinder 124 cc motorcycle engine with an original compression ratio of 9.6:1. The compression ratio was increased to 10.6:1 by reducing the cylinder height by 0.6 mm. Performance testing was carried out using a dynamometer with two types of fuel, RON 88 and RON 92. Octane number 92 was selected based on fuel availability, while octane number 88 was used to evaluate engine performance under an increased compression ratio. A cylinder wall length reduction of 0.6 mm was applied as the maximum allowable limit, beyond which cylinder head modification would be required. The performance parameters evaluated were torque and brake power over an engine speed range of 4000–7000 rpm. The results indicate that increasing the compression ratio from 9.6:1 to 10.6:1 improved engine torque and brake power by approximately 3.8% to 4%. Meanwhile, the use of higher-octane gasoline (RON 92) increased performance by only about 2% to 2.4%, and only when used in the higher compression engine. In contrast, using high-octane fuel in a low-compression engine resulted in reduced performance due to ignition delay. Overall, the optimal performance was achieved when a high compression ratio was paired with high-octane fuel. Therefore, selecting an appropriate octane rating according to the engine compression ratio is essential to achieve optimal combustion efficiency, brake power output, and torque response.
Beyond a Single Damping Coefficient: Experimental Mapping of Nonlinear and Stroke-Dependent Automotive Shock-Absorber Behaviour Avicenna An-Nizhami; Ignatius Gunawan Widodo; Muhammad Showi Nailul Ulum; Elfrida Rizky Riadini; Ahmad Mamba’udin; Yuris Bahadur Wirawan
Journal of Mechanical Engineering and Applied Technology Vol. 4 No. 2 (2026): VOLUME 4 ISSUE 2 YEAR 2026 (JULY 2026)
Publisher : Politeknik Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jmeat.v4i2.7842

Abstract

Shock absorbers are commonly represented by a constant viscous damping coefficient, although their actual force response may vary nonlinearly with piston velocity, stroke amplitude, and operating conditions. This study experimentally compared the damping characteristics of original and aftermarket rear shock absorbers using a laboratory test rig with variable-speed and variable-stroke operation. Both specimens were tested at strokes of 60, 90, and 120 mm and excitation frequencies of 0.5–2.0 Hz, corresponding to peak piston velocities of 0.0942–0.7539 m/s. Maximum damping forces were measured using a force gauge, and the resulting force–velocity relationships were evaluated before and after modification of the test rig. Three-term sinusoidal functions were also fitted to the measured data using the MATLAB Curve Fitting Tool. Both shock absorbers exhibited nonlinear digressive behaviour, characterised by a rapid force increase at low-to-intermediate velocities followed by a stroke-dependent high-speed plateau. Matched-velocity comparisons showed that damping force varied with stroke even at approximately equal peak velocities, demonstrating that the response was not governed by piston velocity alone. Using the post-modification data, the aftermarket shock absorber generated an average damping force 15.8% higher than the original unit over the complete test matrix. Its peak force exceeded that of the original shock absorber by 29.4%, 9.8%, and 12.6% at strokes of 60, 90, and 120 mm, respectively. The corresponding apparent damping coefficients were also consistently higher for the aftermarket unit. These findings demonstrate that shock-absorber performance should be evaluated using experimentally determined force–velocity operating maps across multiple strokes and velocities rather than a single nominal damping coefficient.
Co-Authors Adam Zuyyinal Adib Ahmad Mamba'udin Ahmad Mamba’udin An Nizhami, Avicenna Bahtiar Rahmat Dianisa Khoirum Sandi Elfrida Rizky Riadini Fahmy Zuhda Bahtiar Ignatius Gunawan Widodo Irwan Setyo Prabowo Katiko Imamul Muttaqin Mohammad Burhan Rubai Wijaya Muhammad Akhsin Muflikhun Muhammad Showi Nailul Ulum