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An elasto-hydrodynamic lubrication model is used to study the effects of multi-order journal lobing on the performance of a big-end bearing in a turbo-charged diesel engine. The journal has 5 lobes superimposed with 50 lobes of chatter. Results show that any form of lobing has adverse effects on bearing performance, reducing film thickness and increasing oil film pressure. The effects of low and high order lobing are additive, but the bearing system is more sensitive to high order lobing, i.e. chatter. To improve the reliability of big-end bearing systems lobing on the journal should be minimised especially chatter.

This paper details part of an on-going experimental program to map the operating characteristics of crankshaft bearings. Data from fired engines is essential to validate computer models and enhance understanding of these critical components in the engine system. Oil flow data is particularly valuable when used in conjunction with temperature data, especially at conditions close to the maximum rated engine speed where oil “starvation” effects can be significant. The results from a 2 litre gasoline engine detailing the oil flow, pressure and temperature show that the most challenging areas of bearing performance are at conditions close to the maximum rated engine speed.