Full details: Mercedes-AMG GT's 375kW V8

Mercedes-Benz hotshop, AMG, will deliver 375kW of power to its upcoming GT coupe in an effort to directly attack Porsche.

The twin-turbo 4.0-litre M178 engine, as it is called inside AMG, is the core engine technology that AMG hopes will underpin its sports and sports-sedan future for at least a full generation.

Expected to also find a place inside the engine bay of the upcoming C 63 AMG, the new M178 engine will also crunch out 650Nm of torque from a low point of 1750rpm all the way through to 4750rpm. That’s substantially less than the 800Nm torque peak of the twin-turbo 5.5-litre V8 in the current E 63 AMG S, but it arrives a full 3000rpm earlier in the rev range.

By way of comparison, the outgoing 507 Edition C 63's atmo 6.2-litre V8 is rated at 373kW and 610Nm.

The new twin-turbo 4.0-litre revs out to 7200rpm, its power peak arrives at 6250rpm (750rpm earlier than the 6.2-litre V8) and it helps deliver 94.2kW/litre in specific output.

The high-compression petrol engine boasts four camshafts, direct fuel-injection and two Borg-Warner turbochargers nestled atop the motor. Generating a maximum of 1.2 bar of pressure, the heated air is cooled by a water-to-air intercooler.

With a pair of turbochargers force-feeding the 3982cc V8, the GT’s powerplant is essentially a pair of 2.0-litre, four-cylinder M133 motors from the A 45 AMG stuck together in a 90-degree vee. It boasts a compression ratio of 10.5:1.

It takes other tricks from the A 45 and CLA 45 engine, too, including its sand-cast engine block and its 83mm bore and 92mm stroke dimensions.

The four-year run of the M159 has seen it used in everything from the SLS AMG to the E 63, but it has ceased production in parallel with the SLS coupe.

It promises packaging and handling advantages, too, with the M178 a full 88mm shorter from end to end than the outgoing V8.

The dry-sump motor is only the second turbocharged power plant AMG has ever built and it has turned to Bosch for help with the piezo fuel-injection system, whose capacity for up to seven injections per ignition cycle give it the ability to meet EU6 emissions regulations without dumping power or revs. It has a variably regulated fuel pump capable of up to 200 bar of pressure.

The all-aluminium engine also uses Benz’s Nanoslide material to reduce friction inside the cylinder barrels and fills them with forged aluminium pistons.

AMG also mounts the exhaust directly to the back end of the turbochargers, high up in the vee of the 209kg engine.

The Mercedes-AMG GT, the latest green-camouflaged images of which were presented in AMG's customer magazine, will make its world public debut at the Paris motor show on October 2, before going on sale in Australia next year, priced from around $300,000.