AbstractThe present investigation evaluates the combustion, performance, and exhaust emissions of diesel fuel in blends with either 5, 10, and 15% ethanol, or with 8, 16, and 24% n-butanol, or lastly with 8, 16, and 24% diethyl ether (DEE, an isomer ether of butanol) by volume, fueling a standard, experimental, single-cylinder, four-stroke, high-speed direct injection (HSDI), Hydra diesel engine. The tests were conducted using each of the above fuel blends, with the engine operating at three different loads. Fuel consumption, exhaust gas temperature, and exhaust smoke, nitrogen oxides (NOx), carbon monoxide (CO), and total unburned hydrocarbons (HC) were measured. The differences in combustion, performance, and exhaust emissions of those biofuel blends from the baseline operation of the diesel engine (when working with neat diesel fuel) and among themselves are compared. Fuel injection diagrams, combustion chamber pressure diagrams, and heat release rate (HRR) diagrams obtained thereof, reveal some intere...