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Nowadays, the use of numerical simulations is an important tool in order to optimize the engine and components behaviors, directly contributing to the emissions and lead-time development project reduction. With the increase of engine thermal specific loading, excessive piston carbon build-up may be an issue, eventually causing liner polishing and excessive Lube Oil Consumption (OC). During the development of a Cummins heavy duty 8.9L engine, preliminary engine test results indicated excessive OC levels, above the engine specification limits. Also, a considerable carbon build-up, mainly in the second ring groove, was observed. This paper presents the application of piston rings numerical simulation to predict the piston ring pack behavior and evaluate potential sources of OC which may explain the excessive values obtained in engine tests.

The current SI engine designs submit the engine to operating conditions that require an improved performance of its components. The increase of the engine speed is a trend that generates a significant change in the engine components design approach. During validation tests, some engines have presented blow-by spikes at high speed and low load operating conditions. The reason is an abnormal ring package motion due to the influence of the high inertia and small gas pressure loads. This work presents a numerical simulation of a SI engine considering high speed and no load operating conditions, which showed blow-by spikes during engine tests. The numerical simulation tends to reproduce the blow-by spikes and identify the involved phenomena. Based on the numerical simulation, other engines were analyzed and some guidelines for the piston and the piston rings were developed in order to minimize the blow-by spikes at the mentioned operating condition.