The A45 should have similar styling to the A35 shown here.

Affalterbach - Mercedes-AMG is pushing the four-cylinder boundaries even further with its new-generation A45.

Although the range-topper has yet to be officially revealed, the boys in Affalterbach have officially announced the power and torque outputs for its newly-developed 2-litre engine, codenamed M 139.

Like its predecessor the new motor will have the distinction of being the most powerful series production four-cylinder engine in the world, just by a much bigger margin, with up to 310kW and 500Nm on command, which is 30kW and 25Nm more than before.

Those outputs apply to the A45 S model, which is being offered for the first time, and Mercedes-AMG will still offer a regular A45, with 285kW and 480Nm.

Just think about that for a moment. It wasn’t too long ago that 300kW was extremely impressive for a V8 motor.

But it’s not just about power. The Affalterbach engineers also aimed to make it feel a bit more like a free-revving normally aspirated engine, by carefully balancing the torque curve to produce peak torque at higher revs, that being 5000rpm in the A45 S and 4750rpm in the A45.

It also revs higher than a traditional turbo motor, with the maximum engine speed set at 7200rpm, while peak power is produced at 6750rpm.

The new four-cylinder engine has been completely redesigned and reconfigured, with the turbocharger and exhaust manifold now positioned behind the engine and the intake system upfront, allowing for the flattest possible front section design and more efficient air flow.

The engine also features two-stage fuel injection for the first time - the first stage sees piezo injectors supplying fuel at up to 200 bar, and the second stage allowing additional injection via solenoid valves.

Keeping things cool is a demand-controlled, electric water pump that operates independently of engine speed, and with late activation during warm-up it’s actually able to heat up the block more quickly.

As you’d expect when seeing an AMG badge, the 2-litre engine is hand-assembled on a new production line in Affalterbach using the famed “One Man, One Engine” principle.

IOL Motoring