Overview of Techniques for Measuring Friction Using Bench Tests and Fired Engines 2000-01-1780
This paper presents an overview of techniques for measuring friction using bench tests and fired engines. The test methods discussed have been developed to provide efficient, yet realistic, assessments of new component designs, materials, and lubricants for in-cylinder and overall engine applications.
A Cameron-Plint Friction and Wear Tester was modified to permit ring-in-piston-groove movement by the test specimen, and used to evaluate a number of cylinder bore coatings for friction and wear performance. In a second study, it was used to evaluate the energy conserving characteristics of several engine lubricant formulations. Results were consistent with engine and vehicle testing, and were correlated with measured fuel economy performance.
The Instantaneous IMEP Method for measuring in-cylinder frictional forces was extended to higher engine speeds and to modern, low-friction engine designs. A comparison of historical cylinder friction measurements shows reductions of 85% for late model piston /cylinder bore designs. A technique for accurately measuring overall engine friction was developed and used to assess the benefits of friction modifiers with an ability to measure changes in friction less than 1%.