Mercedes-Benz M139 engine: Difference between revisions

Reciprocating internal combustion engine

The M139 is a turbocharged straight-four engine produced by Mercedes-Benz. It serves as the successor to the M133 engine. It is the first AMG four-cylinder engine to feature two distinct output levels, be assembled by hand under the “one man, one engine” philosophy, and utilize a combined port and direct fuel injection system. At 310 kW (416 hp), upon its introduction, the M139 was the world’s most powerful four-cylinder engine in serial production, achieving a specific output of 155 kW (208 hp) per litre or 78 kW (104 hp) per cylinder.^[1][2] The current top version of the M139 produces 350 kW (469 hp), giving it a specific output of 175 kW (235 hp) per litre or 87.5 kW (117 hp) per cylinder, maintaining its status as the most powerful four-cylinder engine in serial production.

The M139 engine is based on the current M260 engine, an upgraded version of the outgoing M270, sharing the same bore, stroke, and block design. Unlike the standard M260, AMG engineers rotated the engine block 180 degrees. This orientation places the intake system at the front of the engine, while the turbocharger and exhaust headers are located between the engine and the firewall.^[3] This rotation is intended to optimize engine airflow for enhanced performance with shorter paths and fewer diversions. Mercedes-AMG states that this also “allows the flattest possible and aerodynamically advantageous front section design.”^[4] The exhaust valves in the M139 engine are larger than those in the M133 engine to facilitate higher flow. The compression ratio for the M139 is raised to 9.0:1, compared to 8.6:1 for the M133. The two-stage fuel injection system, a first for an AMG four-cylinder engine, employs piezo injectors for direct injection into the combustion chambers as the primary stage, and solenoid valves in the manifolds as the secondary stage to increase specific output.

It uses an electrically assisted turbocharger system supplied by Garrett Motion.^[5]

The M139 engine is available in two main output variants: 285 kW (387 PS; 382 hp) and 480 N⋅m (354 lb⋅ft) for the base version, and 310 kW (421 PS; 416 hp) and 500 N⋅m (369 lb⋅ft) for the S-model.