The book focuses the rough piston skirts and liner surfaces and to incorporate these aspects in two dimensional hydrodynamic and elastohydrodynamic lubrication (EHL) of piston skirts in the initial engine start-up. This research work considers the deterministic roughness asperity with the average flow factor method.The randomly generated surface with deterministic asperity is modelled for piston skirt EHL. For this developed model, parametric studies on the salient features like the engine start-up speed, hydrodynamic load, radial clearance, and viscosity of lubricant, is undertaken.