The disclosed is a combination of a cylinder liner and a
piston ring which contacts to a inner circumference surface of the cylinder liner at the pressure of 0.03 to 0.2 MPa, wherein the composition of the cylinder liner includes,
silicon: 23.0 to 28.0% by weight,
magnesium: 0.80 to 2.0% by weight,
copper: 3.0 to 4.5% by weight, iron: 0.25% by weight or less,
nickel: 0.01% by weight or less, and the rest: unavoidable impurities and aluminum, and wherein
surface roughness profile of the inner circumference surface has Rz 0.5 to 1.0 μm, Rk=0.2 to 0.4 μm, Rpk=0.05 to 0.1 μm, Rvk=0.08 to 0.2 μm, meanwhile, wherein the composition of a
piston ring includes carbon: 0.6 to 0.7% by weight, chrome: 13 to 14% by weight,
molybdenum: 0.2 to 0.4% by weight,
silicon: 0.25 to 0.50% by weight,
manganese: 0.2 to 0.5% by weight, and the rest: unavoidable impurities and iron, and wherein carbides with the
diameter of 5.0 μm and less are contained at the area rate of 4 to 10%, and the
surface roughness of an outer circumference sliding surface is Rz=0.8 μm or less, and RPk=0.15 μm or less.