Part 2: Mercedes-AMG Engines in Depth

Press Release

Part 2: Mercedes-AMG Engines in Depth

One technician, one engine: engines assembled by hand and subject to tight quality controls at Mercedes-AMG

• Hand-crafted engines from manufacturing site in Affalterbach
• Each high-performance engine assembled by its own fitter
• Meticulous: work founded on pinpoint precision and vast experience

At Mercedes-AMG, tradition dictates that each engine be assembled by hand. Each engine is fully assembled by its own AMG fitter who is responsible for the entire procedure: installing the crankshaft in the engine block, fitting the camshafts and the supercharger, routing the wiring and pouring in the engine oil. Once the assembly work is complete, each AMG engine has to undergo performance testing on a comprehensive series of test rigs. Given the strict requirements that have to be fulfilled by AMG high-performance cars, the engine manufacturing facility only employs highly qualified mechanics who have many years of experience. Working by hand is all about ensuring pinpoint precision and being extremely meticulous, even during peak periods when demand is especially high: the 40-strong team of mechanics assemble up to 90 engines per day. Each stage of the process is subject to the same stringent DaimlerChrysler quality criteria that apply to all other Mercedes-Benz series-production engines. After all, as well as delivering high-performance, an AMG engine must display the hallmark Mercedes reliability and longevity.

Part 2: Mercedes-AMG Engines in Depth

The AMG supercharged V6 engine:
powerpack for the SLK-Class and C-Class

• Supercharged V6 with 3.2-litre displacement and 260 kW/354 hp
• 450 Nm: unrivalled peak torque
• Design which draws on experience in motorsport

Sheer power and compact dimensions are the two major features of the AMG supercharged V6 engine. Developing 260 kW/354 hp and 450 Nm of torque, it enables the SLK 32 AMG and C 32 AMG to deliver thoroughbred sports car performance. The supercharged six-cylinder engine enters new realms in terms of torque: this powerful unit produces no less than 450 Nm at 4400 rpm – an absolutely outstanding value which makes the C 32 AMG and SLK 32 AMG the world torque champions among all series-production cars in their segments. The torque band of this supercharged six-cylinder powerplant is equally impressive: more than 400 Nm are available from as little as 2300 rpm; this value remains constant up to 6100 rpm, providing outstanding acceleration at any time. Thanks to the enormous power on tap even at very low engine speeds, gliding along effortlessly in a high gear is likewise a most pleasurable experience. Low consumption with premium unleaded fuel (RON 95) The supercharged V6 engine also delivers impressive fuel economy: with NEDC combined consumption of just 11.2 litres of premium unleaded fuel per 100 kilometres for the SLK 32 AMG and 11.5 litres for the C 32 AMG (Estate 11.9 litres), Mercedes-AMG GmbH demonstrates that sports performance and excitement certainly can be combined with environmental compatibility. Moreover, in contrast to the engines of most competitors, the new supercharged engine is designed to run on widely available premium unleaded fuel (95 RON). All three of these powerful AMG cars already comply with the particularly stringent limits of the EU-4 emission standard which comes into effect from 2005. The most important data for the AMG supercharged V6 engine at a glance, based on the example of the SLK 32 AMG: Helical belt-driven supercharger for a high charge pressure A newly designed supercharger lies at the heart of the powerplant and ensures an unusually high air flow rate. This belt-driven charger is of the helical type with cast aluminium and Teflon-coated rotors. At maximum engine speed, these achieve up to 20,700 rpm, forcing up to 1200 kilograms of air per hour into the six cylinders of the AMG engine. This innovative set-up thus produces a significantly higher charge pressure than conventional belt-driven charging systems. To be specific, the supercharger from Mercedes-AMG produces charge pressures of more than 1.0 bar – that is up to 30 percent more than comparable systems. At 81 kW/110 hp per litre of displacement, the high-performance AMG powerplant has the highest volumetric efficiency of any series-production petrol engine with belt-driven supercharger in the world. Its maximum mean pressure, a figure used by engine specialists to describe the absolute performance of an engine, is 17.7 bar at the maximum torque of 450 Nm at 4400 rpm. With this value the supercharged V6 occupies the peak position among all series-production spark-ignition car engines with belt-driven superchargers.

Part 2: Mercedes-AMG Engines in Depth

Intelligent, electromagnetic supercharger activation In the interests of the greatest possible efficiency, the engineers designed the supercharger so that it would cut in via an electromagnetic coupling, as a function of engine speed and load conditions. Jointly developed with the Japanese company IHI, the supercharger is not continuously driven. Under partial load conditions, the V6 operates purely as a naturally aspirated engine; the supercharger only goes into instant action when the driver wishes to accelerate. Thermal efficiency, fuel consumption and noise/exhaust emissions all benefit considerably from this intelligent solution. The load and engine-speed-dependent activation procedure is carried out by an electromagnetic coupling which obtains its control impulses directly from the newly developed, fully-electronic Bosch ME 2.8.1 engine management system. Naturally the driver feels and hears nothing of the supercharger activation: the build-up of torque is extremely smooth and the supercharged engine shows its muscles very evenly, with power boost already on tap from just above idling speed. Compact charge air cooler located between the cylinder banks To improve efficiency even further, the specialists at Mercedes-AMG have developed an innovative charge air cooler. Mounted between the cylinder banks, this is connected to a separate radiator located at the front of the vehicle in the fresh air stream. In contrast to conventional air/air systems, where the ignition angle and therefore the engine output must be reduced under certain thermal load conditions, this sophisticated counterflow water/charge-air cooler always enables the full output and torque potential of the supercharged V6 engine to be exploited. Design which draws on motor racing know-how To achieve the exceptional performance characteristics and the long operating life typical of a Mercedes, the Mercedes-AMG engineers were also obliged to make significant modifications to the mechanics of the engine. The know-how gained during three decades of motor racing was incorporated into this process, as were the strict Mercedes-Benz standards. Technical highlights include:

• a new crankshaft with bearings adapted to the high torque;
• new connecting rods;
• pistons of highly temperature-resistant material, which defy the high temperatures at peak pressures of more than 90 bar;
• a new balancer shaft suited to the dynamic nature of the engine;
• a new oil pump with a higher throughput for a reliable oil supply to the oil nozzles, whose own throughput was in turn increased by 70 percent, and to optimise the internal engine cooling process;
• lightweight, assembled camshafts;
• harder valve springs to increase the rated engine speed and handle the resulting valve forces.

The modifications to the valve train enabled the rated speed of the series-production engine to be increased from 6000 rpm to 6220 rpm. In addition, the longer stroke and the longer opening times of the intake and exhaust valves allow the six cylinders to be charged more efficiently. To achieve compact installed dimensions for the supercharged six-cylinder engine, Mercedes-AMG dispenses with the usual hot film air mass measurement in the engine management system, integrating a pressure sensor into the charger module instead. All-new AMG exhaust system Technological refinement also marks the AMG sports exhaust system: with the exception of the two manifolds the complete exhaust system of the C 32 AMG and SLK 32 AMG has been redesigned. All four catalytic converters are of ceramic material and feature what is known as thin-wall technology. The larger surface areas in the catalytic converters ensure a reduced exhaust counter-pressure and more rapid heating after a cold start. This benefits both the performance curve and the exhaust emissions.

Part 2: Mercedes-AMG Engines in Depth

Versatile eight-cylinder powerplant:
the AMG 5.5-litre supercharged V8 engine

• 5.5-litre V8 developing up to 270 kW/367 hp used in eight AMG models
• High-tech engine with three valves per cylinder and twin-spark ignition
• Sophisticated exhaust system curbs emissions

The sophisticated 5439-cc V8 engine, which made its debut in the E 55 AMG Saloon in 1997, is used in eight of the models in the Mercedes-AMG GmbH family. Featuring the hallmark three-valve design and twin-spark ignition of all the Mercedes-Benz V6 and V8 engines, the lightweight eight-cylinder unit develops between 255 kW/347 hp and 270 kW/367 hp, depending on model, and delivers maximum torque of between 510 and 530 Nm. With a hefty 450 Nm already on tap at around 2000 rpm, dynamic acceleration and responsiveness are a matter of course. The racing-type forged aluminium pistons – reliably cooled by specially developed oil spray nozzles, even under extreme loads – also play their part, while a newly developed twin-pipe intake system, "assembled" camshafts and variable intake manifold ensure optimal volumetric efficiency and provide the foundation for sporty performance. Low pollutant emissions despite high performance A new exhaust system with larger pipe diameter and modified silencers results in low noise levels and low exhaust backpressure. State-of-the-art catalytic converters and an engine management system tried and tested in countless series of tests ensure effective emission control, meaning that Mercedes-AMG cars with the 5.5-litre V8 engine meet all emissions limits currently in force throughout the world. The most important data for the AMG 5.5-litre V8 engine at a glance, based on the example of the CLK 55 AMG:

Part 2: Mercedes-AMG Engines in Depth

Exclusive to the Mercedes-Benz SL 55 AMG:
the all-new AMG supercharged V8 engine

• Output of 368 kW/500 hp and 700 Nm of torque
• Compressor supercharger with sophisticated intercooler
• High-performance engine with motorsport components

An abundance of power and high-tech components from the world of motorsport – these are the major features of the supercharged V8 engine at the heart of the Mercedes-Benz SL 55 AMG. Developed exclusively for the top-of-the-range Roadster, the eight-cylinder engine has a maximum output of 368 kW/500 hp at 6000 rpm, making the new SL 55 AMG the most powerful of all Mercedes passenger cars. The torque band of the 5.5-litre supercharged engine is equally impressive: at a mere 1500 rpm, the driver can elicit no less than 500 Nm of torque from the V8 engine, rising to 650 Nm at 2000 rpm and 690 Nm at 2500 rpm. The rev counter still only displays 2650 rpm when maximum torque is reached: a massive 700 Nm. Powerful supercharger between the cylinder banks The impressive power development in the eight-cylinder engine is largely down to a newly developed belt-driven supercharger enthroned between the cylinder banks. It works on the principle of a "Lysholm" compressor and achieves about 30 percent more charge pressure than other comparable belt-driven supercharging systems. The compressor screws – Teflon-coated aluminium castings – rotate at over 23,000 rpm (equivalent to an engine speed of 6500 rpm) and, in doing so, press 1850 kilograms of air per hour into the engine's combustion chambers. The maximum charge pressure is 0.8 bar. On the basis of the engine speed and load, The engine management unit calculates whether to activate the screw-type compressor. With lightning speed, the electronic system actuates an electromagnetic clutch which drives the compressor by means of a separate poly-V-belt. The advantage of this direct link to the crankshaft is that the supercharger can spontaneously react when the driver presses the accelerator and provide powerful thrust at an engine speed barely above idle. The most important data for the AMG supercharged V8 engine at a glance: Separate low-temperature circuit for charge air Besides the compressor, the supercharger module houses an intercooler between the cylinder banks. This charge air cooler operates as an air-to-water heat exchanger, extracting heat from the compressed air and transferring it to the coolant. A pump allows the water to flow through a special low-temperature cooler which is located in the cooling module, between the air-conditioning condenser and the radiator. The actual water circuit in the 5.5-litre engine works independently of the low-temperature system for the charge air. An electrical suction-type fan uprated to 850 watts takes the greater cooling requirements of the supercharged engine into account. The oil cooling system is another example of the innovation shown by the AMG engineers: a separate oil cooler is installed in the front apron of the high-performance sports car, the warm air from which is channelled off upstream of the cooling module.

Part 2: Mercedes-AMG Engines in Depth

Emissions meet future EU-4 requirements The AMG engine's exhaust system is just as sophisticated as its supercharger, cooling system and fuel supply. The system has twin pipes throughout (pipe diameter 70 mm). It also has two firewall catalytic converters with extremely thin-walled ceramic monoliths as well as two powerful metal catalytic converters on the Roadster's underbody. A total of four lambda probes in front of and behind the firewall catalytic converters establish the exhaust gas composition and forward the data to the engine management unit. This means the SL 55 AMG meets strict EU-4 emission requirements, even though they are not due to come into force until 2005. Two centre and rear mufflers with a switchover valve between the two exhaust pipes lend the new AMG Roadster its sporty sound. The entire exhaust system is made of stainless steel and, with its four chromed tailpipes, emphasises the extremely powerful character of this top-of-the-range sports car. High-tech engines for superb power delivery and reliability The AMG engineers' vast experience of designing high-performance engines for motorsport stood them in good stead during development of the V8 powerplant. Notable technical highlights of the AMG supercharged V8 engine include...

• ... the crankcase which the engineers adapted by using special transverse screw connections. Measuring 97 mm, the bore is the same as in the standard production engine.
• ... the crankshaft, adapted to the high torque of the supercharged engine using modified bearings and more durable material. The stroke was increased from 84 to 92 millimetres.
• ... the pistons which are made of a special material that is extremely resistant to heat and pressure.
• ... the oil supply which differs from the V8 engine in the SL 500 in that it has a modified oil sump with oil catch tray and front sump as well as a more powerful oil pump.
• ... the cylinder head with optimised intake and exhaust ducts to take account of the higher air flow rate.
• ... the camshafts which are designed for longer valve opening times and thus improve charging of the combustion chambers.
• ... the valve train with a double spring assembly, enabling the rated engine speed to be increased from 5600 to 6000 rpm.
• ... the engine ECU which performs additional tasks for the AMG engine, such as using electronic maps to activate the compressor.