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Mercedes-Benz OM617.912 (2998 cc) specs: 3.0L (183 ci) 5-cylinder, 90.9 x 92.4 mm (3.5787 x 3.6378 in) bore and stroke. Rated 77 hp, 1979–1980.
The Mercedes-Benz OM617.912 (2998 cc) is close to square: 3.5787" bore against 3.6378" stroke, within 1.6%, which splits the difference between a high-revving layout and a torque layout. The 3.6378" stroke puts mean piston speed at 4,000 ft/min around 6,600 RPM, which is where a production bottom end is generally considered at its limit. Each of the 5 cylinders displaces 36.6 ci (600 cc).
It is one of 17 engines in the Mercedes-Benz 183ci family, all of them 183 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated at 77 hp across 1979–1980.
| Displacement | 183 ci / 3 L |
|---|---|
| Bore | 3.5787" |
| Stroke | 3.6378" |
| Cylinders | 5 |
| Compression ratio | 21–21.5:1 (published figures vary) |
| Bore/stroke ratio | 0.984 |
How to tell which you have: Cars built from August 1978 (US 1979 model year on) have the 2,998 cc OM617 with a 90.9 mm bore; earlier cars have the 91.0 mm, 3,005 cc version. Go by the build date on the data plate.
| Fuel type | diesel |
|---|---|
| Advertised HP | 77 hp |
| Years | 1979–1980 |
| Bore/stroke character | 0.984 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,638 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 36.6 ci |
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 |
|---|---|---|
| 1979 | 77 hp | OM617.912 (2998 cc) |
| 1980 | 77 hp | OM617.912 (2998 cc) |
1 factory vehicle, 1979–1980. Each year opens that model's engine table.