Effect of Top Compression Ring Profile on Oil Consumption and Blowby with the Sealed Ring-Orifice Design

The sealed ring-orifice (SR-O) top compression ring was developed to reduce exhaust hydrocarbon emissions and blowby. Oil consumption, however, was often erratic. Results from this study demonstrate that oil control, blowby, and power output can be improved by changing the ring face profile.

Three profiles were investigated: plain taper, taper-sawtooth, and crown. Oil consumption was lowest with the taper-sawtooth and crown-profile rings. The crown-profile rings had the lowest blowby, and their friction and exhaust hydrocarbon emissions were equal to, or less than, those of the other types. Overall, the crown-profile rings performed best.