<div class="section abstract"><div class="htmlview paragraph">This study investigates the influence of Silica-Diamond-Like Carbon (Si-DLC) coated pistons on performance metrics of diesel engine fuelled with various blends of Cassia Fistula biodiesel (CFBD10, CFBD20, CFBD30, and CFBD40). The primary focus is on key performance metrics, including Brake Thermal Efficiency (BTE), Brake Specific Energy Consumption (BSEC), and Exhaust Gas Temperature (EGT). The results demonstrated improvement in BTE and EGT, alongside a reduction in BSEC across all biodiesel blends compared to conventional diesel. Specifically, at full engine load, CFBD10 exhibited a BTE of 33.41%, which is 3.17% higher than neat diesel in the stock engine. At part load and no-load scenarios, improvements of 2% and 0.51% over neat diesel were recorded. During no-load conditions, the BSEC for CFBD10 was measured at 9.901 MJ.kW-hr, 0.738 MJ.kW-hr lower than that of neat diesel. Further increases in Cassia fistula blends resulted in higher BSEC values due to lower calorific content. Exhaust gas temperatures at higher loads were recorded at 330°C, 374°C, 368°C, 360°C, and 351°C for diesel, CFBD10, CFBD20, CFBD30, and CFBD40, respectively, with CFBD10 outperforming neat diesel by 44°C. Specifically, the Si-DLC coating significantly contributes to improved combustion efficiency and thermal management, resulting in higher BTE and EGT. Concurrently, the optimized combustion process facilitated by the Si-DLC coating leads to a decrease in BSEC, indicating a more efficient energy utilization. The scope of this research extends to analysing the implications of Si-DLC coatings in the broader context of automotive engine efficiency and sustainability. These findings underscore the potential of Si-DLC coated pistons in promoting cleaner and more efficient automotive energy solutions. The study aligns SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action), by advancing the development of sustainable biodiesel technologies that enhances energy efficiency in the transportation sector.</div></div>