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The new Mercedes-AMG 45 spec four-cylinder engine, dubbed M 139, has been introduced and it packs more power than ever before.

Mercedes AMG M 139

The much anticipated new Mercedes-AMG 45 engine, the M 139, is finally here and is, at present, the most powerful series-production, four-cylinder engine capable of producing 421 PS and 500 Nm. Its predecessor, the M 133, also claimed that accolade back when it was first introduced with 360 PS.

The new Mercedes-AMG 45 engine has surpassed the previously most powerful M 133 by 40 PS and 25 Nm. The standard 45 makes 387 PS at 6,500 rpm and the 45 S makes 421 PS at 6,750 rpm. Maximum torque has also increased from 475 to up to 500 Nm. With an output per litre of 211.45 PS the new Mercedes-AMG 45 S high-performance turbo-petrol engine is at par with some of the well-known super-sports car engines. Its peak torque is available in a range of 5,000-5,250 rpm for the higher-spec 45 S, or, in standard 480-Nm form, 4,750-5,000 rpm while the engine is capable of 7,200 rpm.

The new engine gets a number of intelligent design features. Compared to the transversely installed M 260 four-cylinder in the AMG 35 models or the preceding M 133 engine, the new Mercedes-AMG M 139 is rotated around its vertical axis by 180 degrees. This means that the turbocharger and the exhaust manifold are now positioned at the rear, on the side of the firewall when viewed from behind. The intake system is therefore positioned at the front. This configuration allows the flattest possible and most aerodynamically advantageous front section design. Furthermore, the new arrangement allows much-improved air ducting with shorter distances and fewer diversions — both on the intake and exhaust side.

Apart from these, there are other enhancements in the engine as well, such as the new roller bearings in the turbocharger shafts — similar to the V8 engines, a new set of electronically controlled wastegate which precisely controls the charge pressure up to a maximum of 2.1 bar (1.9 bar in the basic version). The engine also gets an all-aluminum crankcase which is a chill-cast unit with better material properties, a two-stage, fuel injection system with piezo injectors, for both direct and manifold injection. Furthermore, the cylinder liners gets a Nanoslide coating – used in their F1 racing programme – to reduce friction between the pistons and cylinder walls.

This new engine is assembled by hand in AMG’s Affalterbach facility in a newly designed production line. The company is utilising the “One Man, One Engine” principle to assemble this powertrain, where a single mechanic will be assigned his own separate engine unit in order to maintain higher standards of quality.

Mercedes AMG M 139

We expect to see this new M 139 engine in action under the hood of the AMG A 45 S 4MATIC which is scheduled to debut in the coming months.

Story: Koustubh Mukherjee


About the author: Online Car India



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