The document analyzes the performance and emissions of a diesel engine fueled with blends of biodiesel produced from Delonix regia oil mixed with conventional diesel. Tests were conducted on a single cylinder diesel engine at 1500 rpm under varying load conditions. Biodiesel blends of B25, B50, B75 and B100 were tested and compared to baseline diesel. Results showed that biodiesel blends increased fuel consumption but improved brake thermal efficiency up to 2.5% for B25. Emissions of NOx and CO2 decreased with biodiesel while CO and hydrocarbons increased. Biodiesel also decreased ignition delay and reduced the premixed combustion peak. The conclusions are that biodie