Pistons

Pistons

General Data

Mean Piston Velocity at 5000 rpm
B205 13 m/s
Compression Ratio 8,8:1
Nominal Compression 12 bar

Important: Pistons of different manufacture must not be used in the same engine. The name of the piston manufacturer is cast inside the piston


Piston Types





Pistons





Classification of Pistons and Cylinder Bores

The piston classification is stamped on the piston crown roof. Piston classifications for service are:

AB

B

C

The cylinder classification is stamped on the cylinder face and is specified for each cylinder. The cylinder classifications are:

A

B

B+

They can all occur in the same cylinder block.

Piston Classification

Standard A (not a spare part)
B205 no specification given

Standard AB
B205 89.9664-89.975 mm

Standard B
B205 89.975-89.982 mm

Standard C
B205 no specification given

First Oversize (0.5)
B205 90.457-90.475 mm

Second Oversize (1.0)
B205 90.957-90.975 mm

Piston Clearance, Nominal
B205 0.025-0.056 mm

Classification, Piston/Cylinder

A/A
B205 no specification given

AB/A
B205 0.026-0.056 mm

AB/B
B205 0.055-0.032 mm

B/B
B205 0.025-0.055 mm

B/B+
B205 no specification given

Piston Diameter

Piston diameter is measured at right angles to the gudgeon pin hole, 11 mm from the bottom edge of the piston.

Piston Rings

Thickness
Upper Compression Ring 1.475-1.490 mm
Lower Compression Ring 1.475-1.490 mm
Oil Scraper Ring 2.5 mm

Side Clearance in Groove
Upper Compression Ring 0.035-0.080 mm
Lower Compression Ring 0.040-0.075 mm
Oil Scraper Ring 2.501-2.503 mm

Working Gap in Cylinder
Upper Compression Ring 0.300-0.500 mm
Lower Compression Ring 0.300-0.500 mm
Oil Scraper Ring 0.75-1.00 mm

Gudgeon Pins

Diameter 23.996-24.00 mm
Clearance, Gudgeon Pin/Connecting Rod Bush 0.012-0.021 mm
Length 63 mm