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Nowadays, due to high demand for more efficient engines, new technologies are coming in order to reduce engine size and pollutants emissions, but on the other hand pushing for additional performance by peak cylinder pressure (PCP) increasing. In this scenario, solutions as engine bearing downsizing, number of cylinder reduction and variable compression rate (VCR) has been provided. One of these new technologies is the bushingless connecting rod pin joint system in which the small end bushing is no longer used and the powercell system is composed by the piston pin assembled directly in the connecting rod small end. To enable this downsize with loads increasing, a technology with special micro-profile and coated for mid-range diesel vehicle application was developed, since there is a technical & cost restrictions of current bushings for upcoming PCP.

In recent years, the concern about pollutants emissions has increased along with as customer requirements for more efficient internal combustion engine (ICE). To satisfy these demands, new technologies have been introduced in ICE, such as smaller engine bearings, a reduction in the number of cylinders, variable displacements, peak cylinder pressure (PCP) increases, among other things. Sliding bearings are responsible for vital function under engine operation and also friction losses, impacting on fuel consumption as well as pollutants emissions. To maximize the bearing’s performance, it is important to guarantee a hydrodynamic regime, in order to reduce wear and avoid power loss due to metal-to-metal friction, and consequently, premature failure of engine components. Material roughness indicates, with oil film, the lubrication regime as boundary, mixed or hydrodynamic.

Nowadays, due to the emissions regulations and customer requirements for more economic vehicles there is a demand of more efficient Internal Combustion Engine (ICE). The hydrodynamic bearings play an important rule converting the piston reciprocating displacement into a rotational motion. Thus, considering the sliding bearings vital to define the engine life and also responsible for part of friction loss inside the engine, it is important to optimize its profile and consequently tribological performance parameters which impact on fuel consumption. All in all, this work shows the analysis between lemon shape big end bearing and cylindrical one, in order to evaluate the advantages and disadvantages related to this micro profile.