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Past oil consumption reduction efforts were motivated by operating cost, petroleum conservation, or customer quality perception concerns. Recent efforts have been driven by exhaust catalyst poisoning considerations. The need to certify emissions to a higher mileage level and optimization efforts on the emission control systems have resulted in higher objectives for oil control. This paper focuses on one important factor in the control of lubrication oil consumption in internal combustion engines. Previous studies have related bore finish to oil consumption through either theoretical or experimental techniques. In this study, a mathematical model is derived statistically from experimental data utilizing regression analysis and a new transient radiotracer oil consumption measurement technique. The model predicts oil consumption levels expected with variations in cylinder bore finish, and suggests the important surface finish parameters to specify and control for minimum oil consumption.

Headland ring pistons and rings were developed for a tractor engine that resulted in significant improvements in horsepower, fuel economy, and reduced smoke over a conventional cutback headland piston while retaining the low bore wear, and bore polishing, and low oil consumption advantages of a cutback headland piston. The ring cross section is L-shaped and the ring has near-zero tension when installed in the bore. Cylinder gas pressure is utilized to create the sealing forces on the bore and ring bottom side. The top of the ring is very near the top of the piston. The performance benefits of this design over a cutback head land piston occurs because of better air utilization and lower average top ring friction. Ring sticking problems are alleviated by the 10° semi-keystone radial tail section. Piston durability problems occurring when the conventional piston was redesigned for the headland ring were resolved.