Mercedes-AMG has released full technical details on its brand-new M139 four-cylinder engine، and its headline specs are fairly insane. The turbocharged 2.0-liter inline-four makes a maximum of 416 horsepower، giving it a specific output of 208.9 horsepower per liter. That makes it the most powerful four-cylinder engine in series production، and its specific output is higher than pretty much every modern supercar. And the best part? It will be put in a host of new compact Mercedes-AMG models، almost all of which will come to the United States، as Cae News said.
Before we get totally into the weeds with technical stuff، a little bit more on the basic specs. The engine will come in two trims، base and S. The base version makes maximums of 382 horsepower at 6500 rpm and 354 lb-ft from 4750 to 5000 rpm، while the S puts out its 416 horsepower at 6750 rpm and 369 lb-ft from 5000 to 5250 rpm. (The S generates a bit more boost.) It's a whole lot more powerful than the turbo four in the current CLA45، which makes 375 horsepower and 350 lb-ft، and the new engine's 7200-rpm redline is 500 rpm higher. Wet، the engine weighs a claimed 354 pounds. Unlike the previous engine (and the engine in the new AMG 35 models)، which was mounted transversely، this new one breaths opposite so the exhaust manifold and turbocharger are at the rear (next to the firewall) and the intake system is at the front (next to the bumper). This allows for a flatter front section، which helps with aerodynamics، as well as shorter air ducts with fewer diversions both for the exhaust and the intake.
The twin-scroll turbocharger is new and fitted with roller bearings for the first time، reducing mechanical friction so the turbo can spin more easily. Both the turbine housing and the exhaust manifold are divided so the exhaust flow can be separately fed into the turbine. The wastegate is electronically controlled، allowing for better responsiveness and more precise control of the intake pressure. The turbocharger is cooled by fresh air، oil، and water. Air gets to the turbo housing via a ducted engine cover، which is designed like an air deflector—a technique borrowed from the AMG GT's twin-turbo 4.0-liter V-8. AMG says the M139 has a power delivery akin to a naturally aspirated engine's and a "dynamically increasing" torque curve.