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what it takes to make the most powerful production four cylinder engine

What it takes to make the most powerful production four-cylinder engine?

Some F1 secret sauce but mostly a whole lot of air forced into a turbo is what it takes to make 416hp from a 2.0-litre, four-cylinder engine

Dinesh Appavu Photo

Dinesh Appavu

10 Jun 2019

There’s an old joke regarding the notion of no replacement for displacement. It goes something like, “Only milk comes in two litres.” Well, I’m not sure what they’re feeding the cows in Affalterbach but the new 2.0-litre turbo four from Mercedes-AMG is now the most powerful production four-cylinder engine in the world with 416hp.

Let that sink in for a while as we ship out the abacus to do some maths. 416hp makes for 208hp per liter and an insane 104hp per cylinder that’s the size of a small mineral water bottle. The previous Mercedes-AMG A45 had about 376hp and was already quite a handful but the boys in Affalterbach have gone full loco with the new M193 engine for the new A45, CLA45 and GLA45.

Tuned four-cylinders can churn out well above this easily but production engines need to achieve the same reliably and for the lifetime of the vehicle. That’s the part that’s a pain in the derriere.

AMG says the M193 is based on the previous engine but is fundamentally new with fundamentally more power obviously. Like all new AMG vehicles, it’ll come in two tunes. A base 382hp with 480Nm and a higher “S” trim with the bonkers 416 horses and 500Nm.

Peak torque for the base engine comes in at 5,000rpm while the “S” maximises its twisting force at 6,750rpm; close to the 7,200rpm redline.

One major difference over the older engine is the intake and exhaust routing. AMG swapped them so the transvers-mounted mill has its intake facing front and the exhaust manifold with turbo against the firewall. The reasoning is a less restrictive intake path and a shorter exhaust route to the turbo.

It goes without saying though that countless minor improvements combine to give the new mill a better bite. The turbos not have roller bearings, the block employs a closed deck while the crankcase is aluminium. Even the cylinder bores have a nano coating and cooling is improved with an electric water pump.

Lastly, the head had its exhaust valves enlarged while the fuel injector positioning was fiddled with to make room for aforementioned exhaust valves. Speaking of fueling, the M193 now possesses both port and direct fuel injection.