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Mercedes-Benz OM612 specs: 2.7L (164 ci) 5-cylinder, 88 x 88.3 mm (3.4646 x 3.4764 in) bore and stroke, 18:1 compression. Rated 154 hp, 2002–2003.
The Mercedes-Benz OM612 is close to square: 3.4646" bore against 3.4764" stroke, within 0.3%, which splits the difference between a high-revving layout and a torque layout. The 3.4764" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 5 cylinders displaces 32.8 ci (537 cc).
At 18:1 this is a compression-ignition engine: the ratio is the heat source that lights the fuel, not a knock limit to be managed.
It is one of 2 engines in the Mercedes-Benz 164ci family, all of them 164 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated at 154 hp across 2002–2003.
| Displacement | 164 ci / 2.7 L |
|---|---|
| Bore | 3.4646" |
| Stroke | 3.4764" |
| Cylinders | 5 |
| Compression ratio | 18:1 * |
| Bore/stroke ratio | 0.997 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | diesel |
|---|---|
| Advertised HP | 154 hp |
| Years | 2002–2003 |
| Bore/stroke character | 0.997 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,476 ft/min — conservative for a street engine |
| Displacement per cylinder | 32.8 ci |
| Static compression | 18:1 — high enough that pump premium or better is normally required |
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 |
|---|---|---|
| 2002 | 154 hp | OM612 |
| 2003 | 154 hp | OM612 |
1 factory vehicle, 2002–2003. Each year opens that model's engine table.