Reduction of Friction Losses by Means of Cylinder Liner Offset in a Floating Liner Single Cylinder Engine

Abstract

Piston to liner friction is responsible for a significant part (up to 50%) of total engine friction losses. Engine manufacturers use liner offset designs to address this issue and potentially reduce friction losses as is to be expected from theoretical considerations. A “floating liner” single cylinder engine was used to directly measure the effect of such liner offset design on the friction losses. Results show benefits to be gained at moderate speeds where cylinder pressure effects are the main drivers of piston to liner contact forces. At high engine speed this trend reverses due to piston inertia effects.