# Mercedes-Benz M139 engine

The M139 is a turbocharged straight-four engine produced by Mercedes-Benz. It is the successor of the M133 engine. It is also the first four-cylinder engine by AMG to be specified with two outputs, assembled by hand using "one man, one engine" philosophy, and equipped with a combined port and direct fuel injection system. At 310 kW (416 hp) on its introduction, M139 was the world's most powerful four-cylinder engine in serial production with specific output of 155 kW (208 hp) per litre or 78 kW (104 hp) per cylinder. The current top trim 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, making it the current most powerful four-cylinder engine in serial production.

## Design

The M139 engine is based on the current M260 engine, which is an upgraded version of the outgoing M270, sharing the same bore and stroke dimension as well as the block. Unlike the normal M260, the AMG engineers rotated the engine block 180 degrees so that the intake system is in the front of the engine, while the turbochargers and exhaust headers are situated between the engine and firewall. The rotation optimises the engine air flow for higher performance and with shorter distance and fewer diversions. This also "allows the flattest possible and aerodynamically advantageous front section design." The exhaust valves in M139 engine are bigger than ones in M133 engines for higher flow. The compression ratio is raised to 9.0:1 for M139 from 8.6:1 for M133. The two-stage fuel injection system, a first in AMG four-cylinder engine, has the piezo injectors delivering the fuel directly into the combustion chambers as first stage and solenoid valves in the manifolds as second stage for increased specific output.
An electrically assisted turbocharger system by Garrett Motion is used.

## Performance

The M139 engine has two specific outputs: 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.

## Models

| Engine | Power | Torque | Years |
| M139 | 285 kW (382 hp) at 6,500 rpm | 480 N⋅m (354 lb⋅ft) at 4,750-5,000 rpm | 2019- |
| M139 | 300 kW (402 hp) | 500 N⋅m (369 lb⋅ft) | 2022- |
| M139 | 310 kW (416 hp) at 6,750 rpm | 500 N⋅m (369 lb⋅ft) at 5,000-5,250 rpm | 2019- |
| M139I | 350 kW (469 hp) at 6,750 rpm | 545 N⋅m (402 lb⋅ft) at 5,250-5,500 rpm | 2023- |

### M139 (285 kW version)

* 2019 - Mercedes-AMG CLA 45 4MATIC+ (C118)
* 2019 - Mercedes-AMG A 45 4MATIC+ (W177)
* 2020 - Mercedes-AMG GLA 45 4MATIC+ (H247)
* 2022 - Mercedes-AMG SL 43 (R232)
* 2022 - Lotus Emira (268 kW / 360 hp)

### M139 (300 kW version)

* 2022 - Mercedes-AMG C 43 4MATIC+ (W206)
* 2024 - Mercedes-AMG GLC 43 4MATIC+ (X254)

### M139 (310 kW version)

* 2019 - Mercedes-AMG CLA 45 S 4MATIC+ (Not available in United States until 2025 model year) (C118)
* 2019 - Mercedes-AMG A 45 S 4MATIC+ (W177)
* 2020 - Mercedes-AMG GLA 45 S 4MATIC+ (H247)
* 2024 - Mercedes-AMG GT 43 (C192)
* 2024 - Mercedes-AMG SL 43 (R232)

### M139I (350 kW version)

* 2022 - Mercedes-AMG C 63 S E Performance 4MATIC+ (W206)
* 2024 - Mercedes-AMG GLC 63 S E Performance 4MATIC+ (X254)