The Evaluation of Engine Steady-State Operational Control Using Quality Index

A new method is presented that was used in the setting of engine operational criteria for ASTM¹ engine lubricant tests. The method used steady-state engine operational data obtained through matrix testing and the application of the statistical measure Quality Index (QI) to this data. The use of Quality Index provides for one number to describe both an offset from target and a process's precision. The goal of the Quality Index system is to be able to separate well controlled tests from poorly controlled tests. Quality Index evaluation is applied to engine control parameters such as engine speed, oil temperature and various controlled pressures during test operation. The use of Quality Index allows for a uniform characterization of performance of unrelated and uniquely different controlled parameters. The method presented can be used in deriving steady-state as well as multi-stage controlled performance criteria for engine operation.