This research studies the influence of various blends of sunflower and soybean oil biodiesel with diesel fuel on premixed charge compression engine characteristics, including performance and exhaust emissions, and also investigates the impact caused by oxyhydrogen gas addition on them. The experiments were carried out on a single cylinder PCCI engine which utilizing eight blends of the fuels. Conventional diesel, B20D80, B40D60, B60D40, B80D20, B40D60 + 5 LPM HHO, B40D60 + 10 LPM HHO, and B40D60 + 15 LPM HHO have been used to obtain performance and exhaust emissions characteristics. The hydrogen peroxide additive has introduced into the engine manifold while the diesel/biodiesel fuel blends have been injected directly into the engine cylinder. The results of the studies showed that adding a 40% biodiesel and 60% diesel blend to oxyhydrogen with flow rates of 15 LPM improved the performance characteristics as well as lower exhaust emissions characteristics when compared to the other seven blends. In contrast, conventional diesel had much higher exhaust emissions parameters
