Mercedes-AMG details the most powerful four-cylinder engine with 415bhp

-    The Mercedes-AMG 2.0-litre M139 engine four-cylinder turbo-petrol engine makes 415bhp and 500Nm.

-    Has an output of 210bhp/litre.

-    Will debut in the upcoming A45 AMG.

Mercedes-AMG has revealed the world’s most powerful 2.0-litre, four-cylinder series production engine. The M139 engine – which is set to debut in the ‘45 AMG’ – has an output of 415bhp and 500NNm in its most potent S guise.

With this engine, Mercedes-AMG has exceeded the output of the previous M133 by almost 40bhp. And its maximum torque has also increased by 25Nm. This new engine has an output per litre of up to 210bhp. Its peak torque is available in a range of 5000-5250rpm (4750-5000 rpm in the basic version) while the engine is capable of revving to 7200rpm. 

The AMG engineers have worked upon the power delivery to make it feel similar to that of a naturally aspirated engine. Which means that the increased torque at higher rpm makes the engine feel more free-revving. Compared to the older transversely installed M260 four-pot or the M133 engine, the new M139 engine is rotated around its vertical axis by 180 degrees. Because of which, the turbocharger and exhaust manifold move towards the back near the firewall. Meanwhile, the intake system is positioned upfront thus providing an aerodynamic advantage. This arrangement allows better air ducting – both on the intake and exhaust side.   

Apart from that, there are a lot of other improvements that have gone in and around the engine to make it the most powerful four-banger. For instance, there are now new roller bearings in the turbocharger shafts (like in the V8 engines), charge pressure is up to 2.1 bar from 1.9 bar with electronically controlled wastegate, the all-aluminium crankcase is a chill-cast unit with better material properties, and for the first time, the new high-performance four-cylinder has two-stage fuel injection system with piezo injectors. The cylinder liners are coated with Nanoslide – usually used in Formula 1 engine – to reduce friction. And an engine of such calibre needs a better cooling system as well, which is done using various indigenous methods as well. 

This new engine is entirely assembled by hand at the AMG engine manufactory in Affalterbach. This AMG engine line has also undergone changes to make the engine building process furthermore efficient and convenient for the workers. 

We’ll get to see this new M139 engine in action under the hood of the A45 AMG S which is expected to debut in the coming months.