Article InfoOn a single-cylinder diesel engine, injection pressure can be adjusted by changing the thickness of the injector shim. In this study, the injection pressure of 180 bar (standard), 190 bar (+1mm shim), and 210 bar (+2mm shim) was examined on a typical single-cylinder diesel engine with pure diesel fuel. The tests carried out at a constant engine speed of 1500 rpm with load variations of 650, 1300, 1950, and 3600 Watts to investigate the effect of injection pressure on output power, brake thermal efficiency (BTE), specific fuel consumption (SFC) and opacity. The results showed that increasing injection pressure could increase the output power by 19.3% and 17.4% by adding 1 mm and 2 mm shims, respectively. SFC decreased 1.97% and 12.3% compared to standard conditions and opacity with 2 mm shim was lower than 1 mm shim. In conclusion, increasing the injection pressure from 180 to 210 bar by adding 2 mm shim can improve the performance of a single cylinder diesel engine, which includes output power, brake thermal efficiency (BTE), specific fuel consumption (SFC) and opacity. AbstrakPada mesin diesel satu silinder, tekanan injeksi dapat diatur dengan mengubah ketebalan shim injektor. Dalam penelitian ini, tekanan injeksi 180 bar (standar), 190 bar (+1mm shim), dan 210 bar (+2mm shim) diperiksa pada mesin diesel satu silinder dengan bahan bakar diesel murni. Pengujian dilakukan pada putaran mesin konstan 1500 rpm dengan variasi beban 650, 1300, 1950, dan 3600 watt untuk menyelidiki pengaruh tekanan injeksi terhadap daya output, efisiensi termal rem (BTE), konsumsi bahan bakar spesifik (SFC) dan opasitas. Hasil penelitian menunjukkan bahwa peningkatan tekanan injeksi dapat meningkatkan daya output sebesar 19,3% dan 17,4% dengan menambahkanmasing-masing shim 1 mm dan 2 mm. SFC menurun 1,97% dan 12,3% dibandingkan dengan kondisi standar dan opasitas dengan shim 2 mm lebih rendah dari shim 1 mm. Kesimpulannya, meningkatkan tekanan injeksi dari 180 ke 210 bar dengan menambahkan shim 2 mm dapat meningkatkan kinerja mesin diesel satu silinder, yang meliputi daya output, efisiensi termal rem (BTE), konsumsi bahan bakar spesifik (SFC) dan opasitas. Kata-kata kunci: Mesin diesel, Tekanan injeksi, Daya output, BTE, SFC, Opasitas