The current test was carried out on a single-cylinder engine that was water-cooled, naturally aspirated, direct injection with injector pump on the head, compression ignition (CI), and operating at a speed of 1500 r/min under varying loads. While diesel, Simarouba glauca oil (SO) and hydrotreated fuel (HTSO) were immediately fed into the cylinder as the primary fuel whereas acetylene and hydrogen were pumped into the intake port as a secondary gaseous fuel at a flow rate of 200 g/h and 30 l/min respectively with S. glauca as primary fuel. Experiments were carried out with loads of 25%, 50%, 75%, and 100% for various fuels. The results were analysed and compared in terms of the parameters of the combustion process. An increased brake thermal efficiency (BTE) was observed for HTSO fuel around 2.08% compared with diesel. When compared to conventional diesel combustion, the NO emission is increased for HTSO fuel but drastically decreased for SO + C2H2 fuel of around 19.79% compared to diesel and other emissions like CO, HC and smoke emission are decreased for HTSO fuel of around 22%, 4.16%, and 7.69% respectively compared to diesel.