Mercedes-AMG’s latest sportscar, the AMG GT R, draws heavily on knowledge and technology garnered from its motorsport programs. Active programs in Formula 1 and the Deutsche Touring Masters (DTM) have enabled engineers at Mercedes-AMG to extract a further 74bhp from the handcrafted 4.0-liter Biturbo V8 engine.
“Our sports-car and performance brand AMG has its roots in motorsport and, ever since its formation, has repeatedly faced up to the competition on the racetrack,” explains professor Thomas Weber, member of the board of management of Daimler AG, responsible for group research and Mercedes-Benz Cars development. “These genes are particularly prevalent in the new AMG GT R. Boasting a wealth of technological innovations, the new top-of-the-range model is proof of the close collaboration between our constructors of racing cars and road-going vehicles.”
The heart of the new high-performance athlete is pumping stronger than ever: the Handcrafted AMG 4.0L V8 Biturbo engine in the AMG GT R has an output of 577 hp, which is 74 hp more than the previous top-of-the-range engine in the GT S. The peak torque of 516 lb-ft is available between 1,900 and 5,500 rpm.
The increase in performance has been achieved through the use of new turbochargers with a modified compressor and smaller wastegate in conjunction with revised engine mapping. The boost pressure has been increased from 17.4psi on the AMG GT to 19.6psi. In addition, the exhaust ports have been reprofiled, and the compression ratio modified.
The eight-cylinder engine has been mapped to give a sharper, yet more linear throttle response at all engine speed ranges, which Mercedes states ‘makes the car far easier to control when driving at the limit’. To make this possible, the ECU also takes measurement from accelerometers measuring both acceleration and lateral g-forces.
The 4.0L V8 Biturbo engine retains the same twin- scroll turbochargers as found on the regular GT and keeps them located inside of the cylinder. Referred to as a ‘hot inside V’, Mercedes is keen to highlight that this packaging format has several key benefits: A compact engine design, instantaneous response from the turbochargers free from turbo lag and low exhaust gas emissions thanks to optimum air flow for the close-coupled catalytic converters.
Mercedes-AMG uses an indirect air-to-water intercooling system on the GT R for improved thermal management that uses a separate, two-stage low-temperature water circuit. The first cooler stage involves two parallel coolers in the left and right wheel arch, which work together with the large capacity radiator at the front of the vehicle as a second radiator stage. The downstream water-cooled intercoolers ensure that the charge air compressed and heated by the turbochargers is cooled effectively prior to entering the combustion chambers. It therefore remains at a constantly low level even under full load. A large radiator at the car’s front end ensures controlled cooling of the water circulating in the low- temperature circuit. Extremely short charge-air ducting also benefits engine responsiveness.
The V8 uses an on-demand piezo injector system that ‘ensures a homogeneous fuel/air mixture’, thanks to its electronic control and variable fuel pressure delivery, operating between 1,450 and 2,900psi.
Internally, the V8 uses the same Nanoslide cylinder coating as is used in the Mercedes-AMG Petronas Formula One team’s 1.6-liter hybrid engines. Far harder than conventional cast-iron liners and less susceptible to wear, the coating also helps reduced friction.
Dry sump lubrication ensures constant oil supply even with high lateral forces and allows the engine to be installed lower, thus moving the center of gravity closer to the road and forming the basis for high lateral acceleration.
The engine for the AMG GT R is also fitted by hand in the hand-finishing section of AMG’s production plant in Affalterbach based on the “One Man – One Engine” philosophy. This means that each engine is assembled by a highly qualified engine builder who applies the strictest quality standards. This engineer is responsible for everything from installing the crankshaft in the engine block and assembling the camshafts to wiring the engine and filling it with engine oil – as clearly evidenced by the signature on the AMG engine badge.
Dynamic engine and transmission mounts are likewise installed as standard in the AMG GT R. Engine and transmission mounts assume an important function in the case of a transaxle design: soft mounts improve comfort since they provide more effective decoupling of noise and vibration, however, handling and agility benefit from a generally stiffer mount set-up.
Mercedes-AMG has used dynamic engine and transmission mounts, which adjust their stiffness continuously and almost instantaneously to the respective driving conditions and handling. This function is performed by a further control unit, which identifies handling situations on the basis of CAN data, and is connected to the electronic limited-slip rear differential. The engine and transmission mounts are actuated independently of each other, ensuring that both element is in the most optimal position at all times.
The GT R also features a specially developed titanium and stainless-steel exhaust system that delivers a ‘genuine racing car sound’, whilst saving 13lbs. when compared with the AMG GT S. The exhaust system features two infinitely variable exhaust flaps as standard, which have a direct influence on the sound of the AMG GT R.