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Mercedes-Benz M103 specs: 2.6L (159 ci) 6-cylinder, 82.9 x 80.2 mm (3.2638 x 3.1594 in) bore and stroke, 9.2:1 compression. Built 1987–1992.
The Mercedes-Benz M103 is close to square: 3.2638" bore against 3.1594" stroke, within 3.3%, which splits the difference between a high-revving layout and a torque layout. The 3.1594" stroke does not reach 4,000 ft/min of mean piston speed until about 7,600 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 26.5 ci (434 cc).
9.2:1 is low by modern standards and generally happy on regular pump fuel.
6 factory variants share these dimensions across 1987–1992.
| Displacement | 159 ci / 2.6 L |
|---|---|
| Bore | 3.2638" |
| Stroke | 3.1594" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 9.2:1 * |
| Bore/stroke ratio | 1.033 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Years | 1987–1992 |
| Bore/stroke character | 1.033 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,159 ft/min — conservative for a street engine |
| Displacement per cylinder | 26.5 ci |
| Static compression | 9.2:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1987 | — | M103 |
| 1988 | — | M103 |
| 1989 | — | M103 |
| 1990 | — | M103 |
| 1991 | — | M103 |
| 1992 | — | M103 |
1 factory vehicle, 1987–1992. Each year opens that model's engine table.