The dynamic and lubrication characteristics are all very complex problem in piston-liner analysis, and they have great effect on the power output, vibration, noise emission. In this paper, the numerical model which concludes lubrication part and dynamic motion is established, the lubrication is solved by the finite element method, and dynamic equation is solved by Runge–Kutta. The effect of piston skirt parameters on dynamic characteristics are compared based on a typical inline six-cylinder engine, such as: clearance, offset of piston pin, length of piston skirt, position of bump, curvature parameter and ellipticity of the piston, all the result mainly focus on the slap noise of the engine. All the analyses are very useful to design of piston-liner at the development of the engine, and it can provide the guidance for the design of the low noise engine. diameter of piston offset of the piston pin mass of the piston mass of the piston pin mass of small conrod side length of the conrod speed of the engine wave of the piston mass of the first piston ring mass of the second piston ring mass of the third piston ring radius of the crank-pin width of the first piston ring width of the second piston ring width of the third piston ring initial force of the piston system length of the piston skirt the length from the third ring to the pin center the moment initial of the pin the moment initial of the piston the velocity along x, y, z direction dynamic viscosity of oil film pressure flow factors along x, y direction shear flow factors roughness of surface oil film pressure oil film thickness time velocity of the piston the offset distance relative the mass of the piston the tilt angle of the piston the distance from piston mass center to top of piston skirtedge. the coordinate of the element center the transformed coordinate the long and short axis of oval the crank angle the lateral displacement of the top skirt the lateral displacement of the bottom skirt the cylinder pressure the piston groove pressure in the first ring the piston groove pressure in the second ring the diameter of the cylinder the cylinder pressure force the friction moment the tilt angle the friction coefficient the moment caused by oil film the friction force the distance from the first ring to pin center the distance from the second ring to pin center the connect rod force the elliptic coefficient the ellipticity of the piston skirt the curve fitting coefficient 
Piston dynamic characteristics analyses based on FEM method Part I: Effected by piston skirt parameters