Polymerization and carbon depositson fuel-injector nozzles were also monitored. Ordinary diesel (OD) oil was used as a benchmark forcomparison purposes. Tests included measuring high heating value, kinematic viscosity, specific density,cetane index, pour point, flash point, and Conradson carbon residue. Results showed that, the high calorificvalue decreased with increased coconut oil in coconut-oil blends. On average, the calorific value of allcoconut-oil blends were about 6% lower than that of OD fuel. Density increased with increased coconutoil in coconut-oil blends because of the The layout of the experimental setup is shown in Fig. 1. The indi-rect injection (IDI) diesel engine specifications are shown in Table 1.The instrument used in this investigation was fully equipped inaccordance with SAE standard J1349 JUN90. Performance test wasconducted according to SAE standard procedure SAE J1312JAN90. Aconstant speed of 2000 rpm with variable loads as 10–100 Nm wasselected for performance and emissions tests. The same test proce-dure and practice were followed for all other blended-fuel systems.The engine was adjusted per the manufacturer’s instructions beforerunning the test, and the engine was run-in until corrected brakepower was maintained within a variation of 1% over a period of 8 hcontinuous running. CP Engnering-CADET10 software was used tosave and analyze data.2.1. In-cylinder pressure-measuring equipmentA unit of autoscan engine-combustion-process analyzer incor-porating CAS software was used to study engine combustion. Ahigh-revolution encoder was installed on the frame bolted ontothe frame of the engine test bed. This flexible coupling enabledthe encoder to function well under vibration condition. Then,the encoder was calibrated against the mark top dead center(TDC) of the crankshaft. A Thermo-COMP Quartz pressure sensor6061B Kistler water-cooled precision cylinder pressure sensor wasinstalled to study pressure rise and the peak pressure of the com-bustion system. A workshop-machined adapter was used to mountthe sensor in one existing bore for glow plug. Cylinder pressuresignals were passed onto a 5041C-Kistler-charge amplifier beforebeing recorded on a computer data-acquisition system.