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Mercedes-Benz OM648 specs: 3.2L (197 ci) 6-cylinder, 88 x 88.3 mm (3.4646 x 3.4764 in) bore and stroke, 18:1 compression. Rated 201 hp, 2005–2006.
The Mercedes-Benz OM648 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 6 cylinders displaces 32.8 ci (538 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.
2 factory variants share these dimensions, rated at 201 hp across 2005–2006.
| Displacement | 197 ci / 3.2 L |
|---|---|
| Bore | 3.4646" |
| Stroke | 3.4764" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 18:1 |
| Bore/stroke ratio | 0.997 |
| Fuel type | diesel |
|---|---|
| Advertised HP | 201 hp |
| Years | 2005–2006 |
| 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 |
|---|---|---|
| 2005 | 201 hp | OM648 |
| 2006 | 201 hp | OM648 |
1 factory vehicle, 2005–2006. Each year opens that model's engine table.