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Pistons

Pistons

General data

Different makes of piston must not be fitted in the same engine.


Piston class and cylinder travel

Piston class is stamped on piston crown.

Classification codes Piston diameter
Category A mm 81.920 - 81.930
Category B mm 81.930 - 81.940
Category C mm 81.940 - 81.950
Oversize mm 0.4
Piston clearance mm 0.1


The possible cylinder classes are

Classification codes Cylinder bore
Class A mm 82.000 - 82.010
Category B mm 82.010 - 82.020
Category C mm 82.020 - 82.030
Oversize mm 0.1
Cylinder bore conicity mm < 0.005
Cylinder bore ovality mm ± 0.05


Max weight difference between pistons g 5


Piston rings


Upper compression ring Lower compression ring Oil scraper ring
Piston ring gap mm 0.20 - 0.35 0.60 - 0.80 0.25 - 0.50
Piston ring play in groove mm 0.0985 -0.130 0.025 -0.070 0.030 -0.070
Piston ring thickness mm 1.970 - 1.995 1.970 - 1.990 1.970 - 1.990
Piston ring, groove in piston mm 2.080 - 2.100 2.020 - 2.040 2.020 - 2.040


They can all occur in the same cylinder block.

The piston ring working gaps must be displaced 120° to each other.