ESTUDIO COMPARATIVO DEL DESGASTE EN UN MOTOR DE ENCENDIDO POR CHISPA EN CONDICIONES DE VELOCIDAD VARIABLE USANDO GASOLINA Y GAS NATURAL COMO COMBUSTIBLE A COMPARATIVE STUDY OF THE WEAR-OUT IN A SPARK IGNITED ENGINE UNDER CONDITIONS OF VARIABLE SPEED USING GASOLINE AND NATURAL GAS AS FUELS

The results of a comparative study of the wear-out in a 1.3 liter internal combustion engine using gasoline and Venezuelan natural gas (GNV) are reported in this research. The wear-out evaluation was performed indirectly by measuring worn-out elements in the lubricant through spectrometry of emission during a 100 hour testing lapse. The experiment was carried out in laboratory using an engine with few running hours and in conditions of controlled operation to guarantee a normal wear-out speed. The procedure of starting and warming up included igniting the engine without load at a very slow speed and allowing it to stabilize, then setting it to 1500 RPM. The condition of variable speed was set by cycles of acceleration and deceleration, which were performed 20 times every 15 minutes (from 1500 to 2800 RPM). Oil samples were taken through the oil level gauge every 5 and 20 running hours, subtracting 8 and 100 ml of oil, respectively. Spectrometric analyses were done every 5 hours of cumulative running. The results were corrected considering the variation in the total volume as a result of the samples taken. The wear-out speeds were calculated using the constant speed model of wear-out for systems with oil leakage and additions developed by our group. The study was based on the concentration analysis of iron, lead, copper, tin, aluminum, and silica. The results demonstrate that the wear-out speed of Fe, Pb, Cu and Al is greater using gasoline than GNV in percentages of 434.83%, 734.31%, 145.63%, 146.57% respectively; and the contamination of Si using the alternative combustible GNV is smaller in 24,42% compared to gasoline.