Change from nodular cast iron to steel for compression rings
Use nodular cast iron or steel for oil rings
Wear and Scuff Resistance:
Top compression ring compression ring
Oil Consumption Reduction
CO2 / Friction Loss Reduction
The demand for lower CO2levels brings with it the need for further reductions in piston ring friction loss. To accomplish this there must be a move towards smaller axial widths and radial wall thicknesses and consequently lower tangential forces. However, at the same time the functional values like durability, oil economy and assembly must not be neglected.
Bore Distortion Reduction
The functional values "oil consumption" and "blowby" are critically affected by such factors as engine block design. Low distortions in many cases enable the tangential force to be reduced, resulting in lower friction losses with no adverse effect on oil consumption.
In aluminium blocks with cast-in grey iron liners the bond integrity between the block and liner material is extremely important. The typical gap found between grey iron liners and the aluminium block adversely affects the dynamic performance of the engine (Fig. 32). If the block is produced by high pressure die-casting the use of hybrid liners (grey iron or aluminium liners with an aluminium outer coating) will assure maximum bonding of the liner to the block material especially in the critical TDC region (a quasi-monolithic bond is obtained Fig. 31). Experience in the field shows that this system provides definite improvements in dynamic performance.
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