| Mercedes-Benz M121 | |
|---|---|
 | |
| Overview | |
| Manufacturer | Mercedes-Benz |
| Production | 1955-1967 |
| Layout | |
| Configuration | inline 4 |
| Displacement |
|
| Cylinder bore |
|
| Piston stroke | 83.6 mm (3.29 in) |
| Cylinder block material | Cast iron |
| Valvetrain | SOHC 2 valves x cyl. |
| Compression ratio | 8.5:1, 9.0:1 |
| Combustion | |
| Fuel system | Twin parallel Solex 38PDSJ carburetors |
| Fuel type | Gasoline |
| Cooling system | Water cooled |
| Output | |
| Power output | 75–110 hp (56–82 kW; 76–112 PS) |
| Torque output | 154 N⋅m (114 lb⋅ft) |
| Chronology | |
| Predecessor | M136 |
| Successor | M115 |
The Mercedes-Benz M121 engine was a 1.9 liter single overhead camshaft inline four-cylinder engine introduced by Mercedes in 1955 and used in various model lines during the 1950s and 1960s. Originally rated at 56 kW (76 PS; 75 hp) at 5500 rpm, it replaced the 1.8 liter M136 introduced in 1935, offering improved performance over the M136's side camshaft design.
Applications included mid-size sedans, such as the 190, the 190SL roadster, and trucks such as the Unimog and L319 models.