Combined lubricant–surface system approach for potential passenger car CO2 reduction on piston-ring-cylinder bore assembly

Abstract The impact of reducing friction losses on the fuel consumption and CO 2 emissions was investigated through computational simulation of piston ring dynamics. Experimentally determined cylinder bore surface finishes, low viscosity oil and ring coatings response to oil additives were used as simulation inputs. Oil viscosity grades from SAE10W-40 to SAE0W-4 were considered. 3D roughness measurements of regular and “mirror-like” cylinder bores were used to estimate the flow factors coefficients for the average Reynolds equation and asperity contact stiffness. The combination of smooth cylinder bores, low viscosity oils with appropriate additives promoted ring pack FMEP reductions of up to 66% at part load and WOT with consequent CO 2 reductions of up to 10% at part load and 1.5% at WOT.