Set to be powered by an all-new turbocharged 2.0-liter four-cylinder engine, known as the M 139, the high-performance hatchback will have a base output of 382 hp (285 kW / 387 PS) and 354 lb-ft (480 Nm) of torque. There will also be an S variant which has 415 hp (310 kW / 421 PS) and 369 lb-ft (500 Nm) of torque.
Those are some truly impressive numbers for a four-cylinder engine and they mean the mill develops up to 208 hp (155 kW / 211 PS) per liter. That’s even more powerful than the A 200 which has a turbocharged 1.4-liter engine developing 161 hp (120 kW / 163 PS).
Besides the mind blogging performance specs, the engine revs up to 7200 rpm and has a torque curve which is said to deliver power in a fashion similar to a naturally aspirated engine.
Compared to the turbocharged 2.0-liter four-cylinder in the A35, the new engine is rotated 180 degrees and this allows the turbo and exhaust manifold to be positioned at the rear. This might not sound too important, but it enables the engine to be equipped with a front-mounted intake and improved ducting.
Besides that switch, the engine has a new twin-scroll turbocharger that features a turbine housing with two different flow passages that run parallel to one another. This, along with divided ducts in the exhaust manifold, helps to prevent individual cylinders from negatively influencing one another during load cycles.
Speaking of the turbo, it also adopts roller bearings for the first time. This helps to reduce friction and improve responsiveness.
As for the engine itself, it has an all-aluminum crankcase, a forged steel crankshaft and forged aluminum pistons which reside in Nanoslide-coated cylinder liners. Other highlights include a new two-stage fuel injection system as well as repositioned injector nozzles and spark plugs that allow for larger exhaust valves.
Given the engine’s high-performance, cooling was an important consideration. To cope with the issue, the A45 will have an electric water pump that operates independently of the engine. The car will also be equipped with an additional radiator that supports the main radiator up front.