Mercedes-AMG's New Engine is World's Most Powerful 4-Cylinder
The new M139 from Mercedes-Benz comes equipped with plenty of new hardware that allows it to pump more power and thrust.
New Demand
The current generation of compact cars by Mercedes-Benz demands less weight, different packaging options, more power, and compliance with the necessary emission requirements. This has brought about the need for a redesign of AMG's 45 four-cylinder engine which produced 355 horsepower. According to Ralf Illenberger, head of engine development at Mercedes, the only thing that the new 4-cylinder carries on from its predecessor are a couple of nuts and bolts.
Photos Courtesy of Motor1
Power
The new 2.0-liter 4-cylinder turbo by Mercedes is a replacement of the previous engine that powered the GLA45, CLA45, and A45. In standard form, it produces 382 horsepower at 6,600 rpm and 354 pound-feet of torque at between 4,750 and 5,000 rpm. In its higher-performing S variant, it makes an incredible 416 horsepower at 6,750 rpm and 369 pound-feet of torque at between 5,000 and 5,250 revs. The redline for both trims stands at 7,200 revs. These specs make the new M139 engine the most powerful 4-cylinder engine ever built for a production vehicle.
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Sportier Driving
The goal behind the new engine was to achieve better and more vibrant driving. The team at AMG did this by altering torque delivery. It no longer rises steeply nor levels off over a wide range of revs. The M139 churns more thrust. This helps to improve acceleration, much like what you'd experience in a conventional naturally aspirated power unit. More thrust can be experienced between 1,000 and 2,000 rpm, unlike in the M133 where this was achieved at about 2,000 rpm.
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New Equipment
The M139 receives new equipment from AMG. This includes an upgraded water jacket, valve seats, exhaust valves, as well as oil for cooling the turbo. The water pumps are electrically controlled to regulate temperatures under the hood. The cylinder block and head have dual injectors, exhaust valve control, and a "Camtronic" variable inlet to make the cooling process more efficient.
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Better Delivery
A second set of four injectors has been installed within the inlet system to improve delivery during hard acceleration. According to Illenberger, a single set of injectors per cylinder would be the limit for fuel delivery. It was only fair to include a second set to provide better performance. The Camtronic system triggers two camshafts to heighten the throttle response and to provide good fuel economy.
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Turbo Displacement
The turbo has been moved to the front of the engine thanks to a 180-degree turn of the cylinder head. The system has been equipped with an electric wastegate that features low-friction roller bearings that help to reduce loss of boost when modulating pressure. The M139 requires a lot of cooling. In addition to the cooling system mentioned earlier, the engine cover is shaped to direct the generated airflow towards the turbo. The high-performing S variant takes over the car's air conditioning from time to time for extra cooling.
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Streamlined Production
In addition to providing a better engine, AMG has devised a way of streamlining its production. The team has always applied the "one man, one engine" method when it comes to the development of engines. Don't let the naming of the approach fool you, there's a good number of women taking part in the assembly as well. To save time, the torque exerted on each streamlined power tool attached to the engine is electronically measured. There's also a new arrangement that boosts assembly ergonomics. According to Alexander Kurz, the plant manager, AMG is now capable of producing 140 engines every day thanks to a 25% decrease in the production time.
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A More Powerful Version
When Mercedes debuted the engine, they claimed that it was the most powerful engine ever built. According to Illenberger, the M139 has yet to perform at its peak. The M139 is expected to debut in the A45, a hot hatch that won't be available in the US. However, Americans might get to experience the engine's might in the CLA 45.
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