PRE-RELEASE
Pistons
| Pistons |
| General data |
|
|
|
B205
|
B235
|
|
Mean piston speed at 5000 rpm
|
m/s
|
13
|
15
|
| Important | ||
|
Different makes of piston must not be fitted in the same engine. |
||
| Control values, pressure |
|
|
|
B205
|
B235
|
|
Compression ratios
|
|
8.8:1
|
9.3:1
|
|
Compression, maximum variation between cylinders
|
bar
|
2.0
|
2.0
|
|
Nominal compression
|
bar
|
12
|
14
|
| Piston types |
|
Engine
|
|
R
|
Ø
|
A
|
H
|
|
B205
|
mm
|
74
|
28.65
|
1.4
|
56.2
|
|
B235
|
mm
|
50
|
70
|
3.8
|
56.9
|
| Classification of pistons and cylinder bores |
The piston classification is stamped on the piston crown roof. The piston classes for service are B
First oversize (+0.5)
Second oversize (+1.0)
| Piston classification |
|
AB
|
mm
|
89.964 - 89.975
|
|
B
|
mm
|
89.975 - 89.982
|
|
First oversize (+0.5)
|
mm
|
90.457 - 90.475
|
|
Second oversize (+1.0)
|
mm
|
90.957 - 90.975
|
|
Piston clearance, nominal
|
mm
|
0.025 - 0.056
|
| Piston diameter |
Piston diameter is measured at right angles to the gudgeon pin holes, 11 mm from the bottom of the piston.
|
Classification, piston/cylinder
|
|
Fits cylinder bore
|
|
A/B piston fits both A and B cylinder bores
|
mm
|
90.000 - 90.020
|
|
B piston
|
mm
|
90.007 - 90.020
|
|
Permitted piston clearance
|
mm
|
0.025 - 0.056
|
| Piston rings |
|
|
|
Upper
compression ring |
Lower
compression ring |
Scraper ring
|
|
Thickness
|
mm
|
1.475 - 1.490
|
1.475 - 1.490
|
- 2.500
|
|
Side clearance in groove
|
mm
|
0.035 - 0.080
|
0.040 - 0.075
|
|
|
Working gap in cylinder
|
mm
|
0.300 - 0.500
|
0.300 - 0.500
|
0.75 - 1.00
|
| Gudgeon pin |
|
Diameter
|
mm
|
23.996 - 24.000
|
|
Clearance, gudgeon pin/connecting rod bush
|
mm
|
0.012 - 0.021
|
|
Length
|
mm
|
63
|
