The properties, performance, and exhaust emissions of a four-cylinder indirect injection diesel engine
fueled by FAME from waste coconut oil was evaluated in this study. Polymerization and carbon deposits
on fuel-injector nozzles were also monitored. Ordinary diesel (OD) oil was used as a benchmark for
comparison purposes. Tests included measuring high heating value, kinematic viscosity, specific density,
cetane index, pour point,flashpoint, andConradsoncarbonresidue.Results showed that,thehighcalorific
value decreased with increased coconut oil in coconut-oil blends. On average, the calorific value of all
coconut-oil blends were about 6% lower than that of OD fuel. Density increased with increased coconut
oil in coconut-oil blends because of the higher amount of carbon atoms in coconut-oil molecules. As a
result, viscosity also increased with increased coconut oil in blends. Other properties of blended fuels
varied according to their physicochemical properties. Results also showed that the brake power output
of engine increased by about 5% when fueled by 30% coconut-oil-blended fuel. The average specific fuel
consumption of coconut-oil-blended fuels increased by 7–10% compared with OD oil. The exhaust emissions
of blended fuel were found to be much cleaner, containing less CO, HC, NOx, and smoke and benzene
concentration. The coconut-oil-blended fuel also produced low particulate emission and carbon deposit
on injector nozzles. For each coconut-oil-blended fuel, the engine did not have any starting difficulty and
combustion noise at >25 ◦C. The coconut-oil-based fuel also did not pose a severe environmental threat
because of its low sulfur content.