BMW S58, Руководство пользователя

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S58�Engine
4.�Engine�Mechanical
26
4.2.3.�Piston�with�wrist�pin�and�piston�rings
The�shape�and�material�properties�of�the�piston�have�been�adapted�to�the�higher�demands�in�terms�of
the�high-revving�design�of�the�S58�engine�with�a�rated�engine�speed�of�7500 rpm.
A�forged�slipper-skirt�piston�made�by�the�manufacturer�Mahle�is�used.�The�piston�is�made�from�the
M142P�alloy�(AlSi12Cu3Ni2Mg).�This�alloy�is�particularly�suitable�for�high-performance�petrol�engines.
For�the�S58�engine,�the�piston�alloy�is�formed�by�forging,�which�produces�slightly�different�micro-
structures�and�properties.�That�is�indicated�by�the�suffix�"P"�in�the�alloy�designation.
The�piston�skirt�is�Grafal-coated,�which�is�necessary�due�to�the�LDS-coated�cylinder�liners.
The�piston�diameter�is�84 mm.�The�first�piston�ring�is�a�nitride�plain�rectangular�compression�ring.
The�2nd�piston�ring�is�a�taper-faced�piston�ring.�The�oil�scraper�ring�is�a�nitride�ES�oil�scraper�ring.
S58�engine,�piston�with�wrist�pin�and�piston�rings
Index Explanation
1 Plain�compression�ring
2 Taper-faced�piston�ring
3 ES�oil�scraper�ring