PRE-RELEASE
Pistons
| Pistons |
| General data |
|
Different makes of piston must not be fitted in the same engine.
|
| Classification of pistons and cylinder bores |
The piston is stamped on the piston crown roof.
|
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 cylinder classes available are
|
Classification codes
|
|
Cylinder bore
|
|
Category A
|
mm
|
82.000 - 82.010
|
|
Category B
|
mm
|
82.010 - 82.020
|
|
Category C
|
mm
|
82.020 - 82.030
|
|
Oversize
|
mm
|
0.1
|
|
Taper cylinder bore
|
mm
|
< 0,005
|
|
Ovality cylinder bore
|
mm
|
± 0,05
|
|
Max. weight difference pistons
|
g
|
5
|
| Piston rings |
|
|
|
Upper compression ring
|
Lower compression ring
|
Scraper ring
|
|
Piston ring opening
|
mm
|
0.20 - 0.35
|
0,60 - 0,80
|
0.25 - 0.50
|
|
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
|
|
Clearance piston ring in groove
|
mm
|
0,085 -0,130
|
0,025 -0,070
|
0,030 -0,070
|
All classes can be found on the same cylinder block.
The piston ring opening should be offset 120°
| Gudgeon pin and piston bearing |
|
Gudgeon pin outside diameter
|
mm
|
25.982 - 25.987
|
|
Gudgeon pin, length
|
mm
|
56,4 - 56,8
|
|
Piston bearing, inside diameter
|
mm
|
25.999 - 26.004
|
|
Gudgeon pin, bearing play in piston
|
mm
|
0,031 - 0,014
|
|
Gudgeon pin, bearing play in connecting rod
|
mm
|
0,019 - 0,003
|
|
Inside diameter, piston end's bearing bushing
|
mm
|
26.006 - 26.014
|
|
Gudgeon pin in relation to connecting rod
|
mm
|
Floating bearing
|
