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The feasibility of relating crankshaft free end torsional signals to the misfiring of an individual cylinder has been established in earlier torsional simulation work [1]. This paper advances two diagnostic methods for detection of the IMEP level of individual cylinders. The first method is an enhanced pattern recognition method using both the flywheel torque fluctuation as the primary signal; and the model based reciprocating inertia knowledge for gas pressure torque harmonics determination. The enhanced pattern recognition method ensures IMEP level detection for each individual cylinder. The second method i s based on a reverse simulation algorithm. The dynamic flywheel speed fluctuation is used as the input signal to reconstruct cylinder pressure diagrams for each cylinder. In both methods, a rigorous, multi-mass, lumped mass, elastic crankshaft model is used to depict the mass-elasticity damping system.

In reviewing various industrial software modules used by bearing suppliers and engine companies, we have found a fair level of agreement between them in the final results. We also discovered, however, some unresolved areas which merit further discussion. This paper will focus primarily on those unresolved areas: 1 the treatment of partial groove bearings 2 calculation of oil flow quantity and its associated temperature rise and friction 3 selection of the bearing clearance 4 the optimal location of the journal oil hole in the main bearing 5 prediction of the fatigue endurance life 6 minimum oil thickness allowable 7 the prediction of the wear pattern. Our approach in these areas will be described and then compared with that taken in other industrial softwares.