Mercedes-AMG ‘M139’ 2.0T sets record 310kW output, for A45

We already kind of knew, but now Mercerdes-AMG has confirmed the outputs for the upcoming A 45 AMG super hatch. It will debut a newly-developed M139 engine.

The unit is a 2.0-litre turbo four-cylinder that produces a record-breaking 310kW and 500Nm. This makes it the world’s most powerful four-cylinder production engine ever. With a specific output of 155kW per litre, it matches and even surpasses some supercar engines in this area.

Mercedes confirms there will be an A 45 and A 45 S, the latter of which receives the 310kW output. The base model will produce 285kW and 480Nm, which is still super impressive for a four-cylinder. Tobias Moers, chairman of Mercedes-AMG GmbH, said:

“With the M 139, we have once again impressively demonstrated the engine expertise of Mercedes-AMG. Not only is the output per litre unrivalled for a turbocharged engine, the high level of efficiency also demonstrates that the internal combustion engine still has further potential.”

So, how does the engine achieve such output? Well, it has been designed to offer characteristics usually seen with naturally aspirated engines. It’s free-revving, in other words, and in fact hits maximum power at 6750rpm (6500rpm for base tune). The redline is actually 7200rpm. Peak torque is also achieved a relatively high revs, from 5000rpm to 5250 (4750-5000rpm for base tune).

The engine is obviously very heavily turbocharged, which helps. Specifically, it uses a twin-scroll unit with all-new roller bearings, with an electronically-controlled wastegate, and air, oil, and water cooling. As for the turbo boost pressure, it’s set at a mental 2.1bar (30.4psi) for the S, and 1.9bar (27.9psi) for the base tune.

Other highlights for the M139 include a patented NANOSLIDE coating technology for the cylinder linings, dual-stage fuel injection with combustion chamber and intake manifold sprays, along with roller cam followers and CAMTRONIC variable valve control.

Each engine will be hand-built by one signed technician as part of AMG’s “one man, one engine” philosophy. It will debut in the new A 45 hot hatch, which is expected to be unveiled very soon. Check out the preliminary specs below:

Technical data at a glance

Mercedes-AMG
M 139 2.0 litre turbocharged four-cylinder engine
Displacement 1991 cc
Bore x stroke 83.0 x 92.0 mm
Output 310 kW (421 hp) at 6750 rpm (S-model)

285 kW (387 hp) at 6500 rpm (basic version)

Peak torque 500 Nm at 5000-5250 rpm (S-model)

480 Nm at 4750-5000 rpm (basic version)

Max. engine speed 7200 rpm
Compression ratio 9.0:1
Turbocharging One twinscroll turbocharger with roller-bearing compressor and turbine wheels
Max. charge pressure 2.1 bar (S-model)

1.9 bar (basic version)

Mixture formation Combined direct and manifold injection.

1.) Third-generation multiple direct injection. Fast and precise piezo injectors spray the fuel into the combustion chambers at high pressure

2.) Additional intake manifold injection with solenoid valves

Cylinder head Two overhead camshafts, 16 valves, adjustable intake and exhaust camshafts, CAMTRONIC valve timing adjustment for the exhaust camshaft
Max. air mass throughput 1,200 kg/h (S-model)

1,100 kg/h (basic version)

Engine weight (wet) 160.5 kg

Brett is the editor and founder of PerformanceDrive. He's obsessed with driving, having played with Matchbox cars until he was tall enough to drive a real one. After initially working as a mechanic, Brett earned a degree in journalism and entered media as an editorial assistant at Top Gear Australia magazine. He then worked at CarAdvice.com.au. His dream is to live next door to the Nurburgring in Germany.