A Literature Review of the Effects of Piston and Ring Friction and Lubricating Oil Viscosity on Fuel Economy 780673

This paper reviews piston and ring friction which can account for 65% of the mechanical friction in an internal combustion engine. It shows that cylinder liner lubrication is predominantly hydrodynamic with localized contact between ring and liner at TDC firing. The degree of contact may increase during transient conditions. Piston ring friction in the hydrodynamic region is proportional to the square root of the viscosity. The viscosity is affected by temperature and pressure which can reach peak values of 340°F and 4000 psi, respectively. Gains in fuel economy through viscosity reductions have been reduced in the last 25 years due to changes in piston and ring design.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.