11
377_057
377_058
377_062
Piston
For strength reasons forged pistons with a slightly
higher weight than conventional pistons is used.
Both engines have the same piston geometry.
– Piston weight
without rings: approx. 290 g
– Piston pin: Ø 20 mm x Ø 11.5 mm x 40 mm
Con-rod
Cracked con-rods made of 36MnVS4 are used in the
basic engine while the conventionally split con-rods
in the RS4 engine are made of 34CrNiMo8 for
strength.
In addition, the geometry of the con-rods was
reduced for the high-revving engine and the toler-
ances were reduced.
– Bearing journals: Ø 54 mm
– Bearing bushings: 1.4 mm thick,
15.25 mm wide
– Length of bushing: Ø 20 mm rolled
– Con-rod length: 154 mm
Cracking
During the cracking process, the con-rod is split at a
predetermined breaking point using a special tool.
The resultant unique breaking surface ensures the
high joining precision of the two mating parts.
Breaking surface
Predetermined
breaking point
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