Effect of fuels on the piston rings of the flexfuel engines

The present study, describes the characteristics of wear of two specimens groups of piston rings of the first piston groove of internal combustion engines. Gasoline engines rings are the first group to be investigated and rings of flex-fuel engines are the second group investigated. Thus, the main objective of this study is to investigate potentially irregular wear between these two engine groups, according to their technologies, regarding the use of gasoline, ethanol or blend fuel in any proportion. In the method used, the piston rings were collected in an automobile repair and engine reconditioning shop, then they were properly cataloged and marked. The specimens are intentionally of high mileage, to achieve the research purposes. The investigation was divided into three steps. The first step involved the measurement of ring heights, thicknesses and rings outer diameters, to compare them with the original measurements provided by the manufacturers and to compare the groups of gasoline engine and flex-fuel engine. In the second step, the rugosimetric parameters of the specimen surfaces were checked with a rugosimeter, for comparison between the two groups studied. Subsequently, in the third step, using a scanning electron microscope (SEM), microscopic analysis was performed on the contact surface coating of the piston rings. It was found that, indeed, there are differences between the two groups of piston rings with respect to wear. It was concluded that the wear of the rings of the two groups of engines is quantitatively similar. However, as for the rugosimetric analysis, a great qualitative variation was observed in the rings of flexfuel engines compared with gasoline engine rings.