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This work presents an experimental study to analyze the influence of surface finishing on engine journal bearing performance. Bimetallic bearings were manufactured with two bored finishings, one called conventional and another microprofiled. Microprofiled bearings have a potential advantage due to the higher conformability of these parts under the engine operational conditions. Bench tests and engine test were conducted in order to check the loading carrying capacity (LCC) until seizure occurrence; the temperature was evaluated at the steel back of the tested parts. Surface of the parts was evaluated after the tests. The results showed that microprofiled bearings presented slightly lower temperature at steel back during the bench tests than the conventional bearings. The loading carrying capacity for both parts was similar, due to the relatively low speed test.

This paper presents some definitions about the bore surface finishing and its influence on the piston rings performance. The surface finishing of a cylinder is in most of cases obtained by a machining process called honing. In recent years, developments and innovations to the honing process have been implemented. These new surface finishings are being implemented in order to improve the working condition of the system. Some of these developments are presented. This paper also presents some benchmarking of bore finishing for SI engines and case studies showing the influence of the surface finishing on the rings performance, regarding wear, friction and lube oil consumption. The results showed that smoother bore surfaces presented lower friction coefficient and also lower wear on the rings and bores. Finally a recommendation for bore finishing and its evaluation for modern SI engines is given.

The demand for higher output performance engines has lead to the increase of PCP (Peak Cylinder Pressure) and more aggressive engine designs for cylinder liners, mainly for new heavy duty engines developments where low cost components are been introduced. Such trends have generated demands to adequate the liner design by improving its material properties by changing its chemical composition, new materials data or even by introducing more accurate casting manufacturing process. Therefore, there is a clear tendency to development more and more alternative solutions that combine a certain technical high-value added and low cost. The most important material properties for cylinder liners are the ultimate tensile strength (UTS) and the fatigue tensile strength. Both parameters confer to the cylinder liners, especially for wet top flanged designs, the ability to survive under high mechanical and thermal load conditions even with reduced wall thickness.