Two methods have been developed at the Walter E. Lay Automotive Laboratory, University of Michigan for measuring instantaneous piston and ring friction in a diesel engine. These have been termed the Instantaneous IMEP and the Fixed Sleeve methods. The Instantaneous IMEP method has been successfully applied to the 903 engine. Inaccuracies in the method from differencing forces are probably great enough to preclude absolute judgments about piston and ring friction forces. On the other hand, the method is expected to show significant changes arising during engine operation in unmodified engines. The Fixed Sleeve method has been implemented in a gasoline engine and appears very promising. Extension to the 903 diesel has been made but no results have been obtained to date.

Assessment of piston and ring friction in low heat rejection or adiabatic diesel engines is expected to be of critical importance to these engines. Application of one or both of these experimental measurement techniques is projected to provide that required friction assessment.

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