THE EFFECT OF THE LEVEL OF UNSATURATION AND OF ALCOHOL MODIFICATIONS OF PLANT OIL FUELS ON THE LONG TERM PERFORMANCE OF A DIRECT INJECTED DIESEL ENGINE

A 200-hour durability screening test recommended by the Engine Manufacturers Association was adopted to study the effects of four alternate fuels on the long-term performance of a four cylinder, direct injected diesel engine. Tested fuels included diesel fuel (control), a 25-75 blend by volume of alkali-refined sunflower oil and diesel fuel, a 25-75 blend by volume of high oleic safflower oil and diesel fuel, a non-ionic sunflower oil-aqueous ethanol microemulsion and a methyl ester of sunflower oil.; Least squares regression procedures were used to analyze the long-term effects of the test fuels on engine performance and to compare the test fuels. Time of the engine operation had a significant effect only on exhaust temperature. For all other response variables, time was not a factor. However, significant differences between tested fuels were observed.; An analysis of variance was employed to compare CRC carbon and lacquer ratings, as well as wear of engine parts. The carbon deposits produced by the microemulsion and the 25-75 sunflower oil blend were significantly heavier than those generated by the other tested fuels. None of the fuels produced excessive engine wear.; The 25-75 sunflower oil blend and the microemulsion caused problems with the fuel injection system.; Except for the microemulsion, lubricating oil consumption, blow-by, lubricating oil viscosity and lubricating oil dispersivity were acceptable for fuels.; It was shown that the level of unsaturation and type of the alcohol modifications of plant oils have significant influences on long-term engine performance.; Only a fuel with a level of unsaturation and viscosity similar to the 25-75 safflower oil blend and a methyl ester of a plant oil can be considered suitable alternate plant oil fuel candidates.