New Mercedes-AMG 4-Cyl. Engine Tops 400 hp

Daimler AG’s new turbocharged 2.0-liter turbocharged 4-cylinder engine tops out at 415 hp and 369 lb-ft of torque, which the carmaker says makes it the most powerful series production 4-banger.

The potent 2.0-liter will be used by Daimler’s Mercedes-AMG performance marque in several upcoming compact models, including the A45 A-Class, CLA45 and GLA45. Daimler ramped up production of the engine, known internally as the M 139, this week at its plant in Affalterbach, Germany.

The base version of the M 139 generates 382 hp and 354 lb-ft of torque, which still is more powerful than the 4-cylinder mill used in the outgoing 45 models. Aside from a few nuts and bolts, Daimler describes the M 139 as an all-new system.

The new engine features a twin-scroll turbocharger that generates nearly 28 psi of boost in the base version and more than 30 psi in the S variant. An electric wastegate minimizes boost loss when pressure modulation is required, according to the carmaker.

Both versions of the engine redline at 7,200 rpm. Peak torque is available between 5,000 and 5,250 revs, while horsepower maxes out at 6,750 rpm.

The engine sports four valves per cylinder, two-stage fuel injectors and two overhead camshafts. The cylinders are bored out to 83 mm and have a 92-mm stroke.

Other new features include larger exhaust valves/seats, a redesigned coolant system and electrically controlled water pumps. A new “Camtronic” system enables variable inlet and exhaust valve control. Drivers can choose between two camshaft profiles to maximize throttle response or fuel economy.