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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 use of Biodiesel is one of the main drivers behind biomass fuels for diesel engine use. This paper compares the performance of powercell components after 100 thousand km field tests using different fuel variants. The tested engine was a 3.0L High Speed Diesel with 120kW @ 3800rpm. Two variants of B5 fuels were tested: one with oil from Soy Bean and other from Castor Bean. Each type of fuel, including regular Diesel, was tested twice. Compared to regular Diesel, the engines tested with B5 presented similar performance [1]. The evaluated powercell parts were: piston, rings, bearings, and cylinder bores. The parts were evaluated in terms of wear, seizure and corrosion. The parts from the B5 tests presented similar visual characteristics after test compared with regular Diesel. A slight wear increase was observed on the parts that ran with the B5 variants. In the case of bearings, corrosion residues were observed with B5 from Castor oil.

Modern SI engines focusing on CO2 emission reduction has been applying flex fuel technology to enable burning biomass fuels. The prime route is the use of ethanol fuel on these engines. The action of designing an engine to run with ethanol and gasoline (Flex-Fueled Engines) affects powercell components in different ways. The mechanical loads are higher to ethanol fuel. The combustion pressure can be increased without the risk of knocking for ethanol while for gasoline the compression rate of the piston is limited due to knocking occurrence. The spark time also occurs earlier which impacts components lubrication once the maximum load happens near the top dead center (TDC) where the sliding speed is lower and consequently there is lower oil film thickness. Such combination of spark time and sliding speed may also affect dynamics which can affect inertia and load composition of engine components.

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.

The reduction of oil demand for automotive engines has been driven recently by the need to reduce oil pump capacity so that benefits from having a smaller size, including a reduction in power loss and CO₂ emissions. Crankshaft bearings are generally attributed to be the largest consumers, main bearings in particular since the supply pressure in the upper bearing shell oil groove over a large arc (circumferentially) coincides with high average clearance. Measurements of oil flow indicate that the main bearing groove is significant and there is a trade-off between lower oil flow and higher bearing temperatures. All solutions must ensure that the oil supply to the big-end bearings via crank drillings is not compromised. Numerical simulation tools can be used to predict and optimize the total oil flow required by the engine lubrication system. In this work, the Elasto-Hydrodynamics Simulation (EHL) was used to analyze the oil flow required by the crankshaft main bearings.

The market has recently required the bearings to operate under intermittent or occasionally boundary lubrication conditions through requirements guided basically by CO₂ reduction: flex-fueled engines, stop-start operation, specification of low viscosity oils, extension of high speed regimes with low stiffness conrods and crankshafts. The sensitivity of the oil film rupture, higher loads and the robustness of operation required the development of low friction coatings or overlays with improved wear resistance. MAHLE response to these requirements has been addressed through a newly developed product assigned as polymer-coated bearing. The polymeric overlay has a proprietary low friction solid blend and it is sprayed onto premium bimetallic bearings. In this paper it is shown that these bearings run at lower temperature, with lower friction and can support higher loads than the conventional bimetallic bearing.