New AMG M139 Engine is the Most Powerful Four-cylinder in the World
AMG M139 engine offers almost 209 horsepower-per-liter, which is unrivaled among small engines.
The Mercedes-Benz AMG division is best-known for big, powerful engines, but with the rising cost of gasoline coupled with governmental pressure to constantly low vehicle emissions, Daimler’s high performance branch is looking towards the future. That future is likely to rely on small engines to go fast and with the introduction of the new M139, it is clear that AMG doesn’t have any problems making big power with a little engine.
In fact, with the 2.0-liter, four-cylinder mill offering 416 horsepower and 369 lb-ft of torque, the M139 is the most powerful four-cylinder production engine in the world while the specific output of nearly 209 horsepower-per-liter make it one of the most efficient production engines of any size from any automaker in the world.
Today, bring you a look at what makes the AMG M139 engine so powerful, along with a look at which vehicles will soon benefit from this powerful little engine.
High Performance Core
The cornerstone of the new Mercedes-Benz AMG M139 engine is a chill-cast aluminum block, which is constructed by pouring molten aluminum into a water-cooled mold, resulting in a particularly dense and very strong structure. This block features a closed-deck design that is borrowed from the racing world that keeps weight low and strength high, allowing this engine to stand up to extreme combustion pressure.
Inside of that aluminum engine block is a forged, high-strength steel crankshaft that moves the forged aluminum connecting rods and pistons. The cylinder walls are Nanoslide-coated in similar fashion to the Mercedes Formula 1 engines, helping to reduce friction and heat during combustion.
Top End
The AMG M139 engine employs a new cylinder head design that has the spark plugs and the fuel injection nozzles located in the cylinder heads for better efficiency and larger exhaust valves help to remove the hot gasses from the engine in a hurry. Those valves and the intake valves are controlled by dual camshafts mounted in the heads, of course, with Mercedes’ Camtronic variable valve timing system leading to a better combination of low-end torque and high-end horsepower.
As mentioned above, the M139 has fuel injector nozzles mounted in the cylinder head ports, but there is also a secondary, direct injection system that adds more fuel when boost pressures reach their peak.
Finally – and perhaps most significantly – the M139 features a new twin-scroll turbocharger, featuring AMG’s first application of roller bearings. That turbo is fed by a divided exhaust manifold design and the wastegate is electronically controlled, allowing for better boost pressure control. Like the twin turbo V8 in the AMG GT, the M139 uses a ducted engine cover to provide cooling air to the turbocharger in addition to the water cooling efforts.
Big Cooling System
The key to making big power from a smaller, forced induction engine is keeping everything cool and to do so, the M139 has two radiators and the intercooler unit, with all three cooling channels being controlled by a variable speed electric pump. Even the engine computer cooling is taken into consideration, with the engineers mounting it on the high-flow air filter assembly.
Non-mechanical Information
The new M139 engine will first be offered in the AMG A45 hatchback, but that isn’t likely to be offered in the United States. The first vehicles to utilize this new engine in the U.S. market should be the CLA45, the GLA45 and the GLB45. In each of these vehicles, the powerful little engine will be mated to a 9-speed automatic transmission and a high performance all-wheel-drive system.
The M139 will be hand-built at the AMG engine facility in Affalterbach, Germany, under the brand’s “One Man, One Engine” program. It will have its own production line in the plant and every engine will have a plaque with the name of the technician who proudly handled the build.
Photos: AMG
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