Mercedes-AMG has developed a new 5.5-liter V8 engine which combines powerful eight-cylinder performance with the economical fuel consumption of a four-cylinder. This unrivalled efficiency is achieved thanks to the AMG Cylinder Management cylinder shut-off system developed exclusively by Mercedes-AMG. Just like powerful, 750 hp eight-cylinder Formula 1 racing engines, cylinder shut-off is used primarily to save fuel.
Thanks to fuel savings of around 30 percent compared to the existing AMG 5.5-liter V8 engine, the high-revving naturally aspirated eight-cylinder demonstrates the great innovative strength of AMG while simultaneously demonstrating the potential still available in naturally aspirated eight-cylinder engines.
In line with its “AMG Performance 2015” strategy, Mercedes-AMG is meeting its promise to continuously reduce both the fuel consumption and emissions of new models over the next few years with the new V8 motor - while reaching new heights with the central brand value of “Driving Performance.”
The high-tech M152 engine not only stirs emotions with its extraordinary power delivery and torque, but also thanks to a combination of advanced technologies which is unequalled anywhere in the world. No other gasoline engine features direct injection at a pressure of 2,900 psi, spray-guided combustion and piezo-injectors in conjunction with map-controlled cylinder shut-off, an all-aluminum crankcase with “spectacle” honing, four-valve technology with continuous camshaft adjustment, a high compression ratio of 12.6 : 1, an ECO stop/start system and generator management - while revving to a maximum of over 7,000 rpm. All these design features lead to high thermodynamic efficiency, which is the foundation for high fuel efficiency and low exhaust emissions.
The AMG Cylinder Management cylinder shut-off system, developed completely by Mercedes-AMG, significantly improves efficiency: cylinders two, three, five and eight are cut off under partial load, which considerably lowers fuel consumption. This technology is similar to what’s used in the 750 hp V8 engines used in Formula 1. Since efficiency also plays a major role in this ultimate form of motor racing, two or four of the eight cylinders are cut off when cornering at low speed, during Safety Car laps or for pit stops.
A generator management system makes a further contribution to fuel economy: whenever the V8 engine is in overrun or when braking, kinetic energy is used to charge the battery rather than being wasted as heat in the usual way. In all other operating modes a combination of onboard network and generator management enables the generator to be kept at a low voltage. This reduces the load on the engine as well as fuel consumption when in city traffic with its frequent overrun and braking phases.
For the first time AMG is using a sports exhaust system featuring an exhaust flap on each side. This technology resolves the age-old conflict of an emotional sound during spirited driving and a more discreet engine note at low speed operation.
Further component tests for the AMG Cylinder Management system were carried out using a perspex cylinder head. The AMG developers used this to analyze the complex system of oil supply ducts and selectable compensating elements in a wide range of operating conditions, e.g. when starting or at high engine speeds. This enabled extraneous influences such as air intrusion into the oil circuit to be easily identified for optimization of the system. Only after the component tests was the cylinder shut-off system tested and verified in a complete engine on dynamic simulation test benches.
The goal of the detailed bench tests was to verify the performance of all the engine components, including the accessories. All the measurement data for the engines examined were systematically compared, and evaluated using reproducible test methods. The functioning tests were accompanied by endurance testing: to ensure the very highest quality standards over their entire operating life, the new AMG V8 engines were required to undergo 8,000 hours of endurance testing.
The SLK55 AMG test cars were taken on extended stop-and-go journeys in a number of large cities. This enabled the interaction between the different engine and transmission control units to be painstakingly examined, as well as the influence of the ambient temperature on the operating modes of the new V8 engine. Another major focus was on the further development of the control software, and its constant adaptation to the different onboard systems and environmental requirements.
Another important engine in the AMG story was the M117, its first eight-cylinder unit with four-valve technology. With a displacement of 5.6 liters, 355 hp and 376 lb-ft of torque, this V8 accelerated the 300 CE 5.6 AMG to a top speed of 188 mph in 1987. This made the coupe the fastest German car in series production, and American fans reverently christened it “The Hammer”.
Closely related to the new M152, the AMG 5.5-liter V8 biturbo engine delivers between 518 hp and 563 hp depending on the model, and a maximum torque of between 518 and 664 lb-ft. The M157 is regarded as the most efficient engine in its output and displacement class. The supercharged AMG 5.5-liter V8, the AMG 6.3-liter V8 and the AMG 6.0-litre V12 biturbo were all able to win the Best Performance Engine category several times in the International Engine of the Year Awards.
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