PISTON-RING SCUFFING as a Criterion of OIL PERFORMANCE 430129
CONDITION of engine parts after testing under standardized procedure is the only satisfactory evidence for comparing the lubrication qualities of different oils, Mr. Keller concludes, showing the detailed set-up for such engine testing.
Of seven pertinent operating variables, all except cooling conditions and oil supply were held constant. The five were power, speed, fuel mixture strength, detonation, and cylinder, piston, and ring design.
Because experience has shown that detonation can destroy satisfactory cylinder lubrication and lead to excessive wear and ultimate failure, fuel having an octane rating of iso-octane + 0.8 cc tel (Aviation Test Method) was used for most of the test work reported. A Waukesha Cooperative Universal Engine fitted with a Wright Cyclone C9GC production cylinder and piston assembly, 6⅛ x 6⅞ or 202½ cu in., was used.
Prior to the test the cylinder barrel was lapped with Minnesota 3M compound No. 500-2-A, with an old piston and old rings as the lapping surface. This was to eliminate any surface deposits from the previous test. The oil system and interior of the engine were flushed with solvent naphtha and then with the oil to be tested. A fresh charge of oil was used for the run-in and for the test itself.
Combined researches of metallurgists, petroleum chemists, and engine designers during the past 10 years, the author says, has resulted in an engine with a 100% increase in power output, a 50% reduction in specific weight, and a 20% reduction in specific fuel consumption.