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Mercedes-Benz M104.991 specs: 3.2L (195 ci) 6-cylinder, 89.9 x 84 mm (3.5394 x 3.3071 in) bore and stroke, 10:1 compression. Built 1994–1997.
The Mercedes-Benz M104.991 is oversquare — the 3.5394" bore exceeds the 3.3071" stroke by 7.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.3071" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 32.5 ci (533 cc).
10:1 is in the range that usually runs on pump premium.
It is one of 5 engines in the Mercedes-Benz 195ci family, all of them 195 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions across 1994–1997.
| Displacement | 195 ci / 3.2 L |
|---|---|
| Bore | 3.5394" |
| Stroke | 3.3071" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 10:1 * |
| Bore/stroke ratio | 1.07 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Years | 1994–1997 |
| Bore/stroke character | 1.070 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,307 ft/min — conservative for a street engine |
| Displacement per cylinder | 32.5 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| 1994 | — | M104.991 |
| 1995 | — | M104.991 |
| 1996 | — | M104.991 |
| 1997 | — | M104.991 |
1 factory vehicle, 1994–1997. Each year opens that model's engine table.