Mercedes-Benz M121 engine
| 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. Rated at 56 kW (76 PS; 75 hp) at 5500 rpm in its base version, it replaced the 1.8 liter M136 introduced in 1935, offering improved performance over the M136's side camshaft design. The engine's first application was in the W121 Mercedes 190SL luxury roadster in May of 1955, in a high-performance 105 hp (78 kW; 106 PS) M121 BII version.
Applications included mid-size sedans, such as the 190, the 190SL roadster, and trucks such as the Unimog and L319 models. The M121 series was in production until 1967, when the M115 engine took its place.