Press Release
Design and materials
Know-how from motor sports
- Particularly rigid bedplate crankcase of closed-deck design
- Cylinder walls with a unique, revolutionary TWAS coating
- Completely new dual-length intake manifold with integral throttle flaps
- Vertical air ducts, valve control by bucket tappets
- Completely autonomous development from Affalterbach
Sophisticated air ducting for a high output
Apart from the large overall displacement of precisely 6208 cc, the extremely high output and torque is above all due to the sophisticated intake system ??????????????????????????????????????? a completely new departure for AMG. Together with the innovative, variable intake manifold of magnesium with two integral throttle flaps, the large air intake cross-sections familiar from motorsport, the streamlined design of the intake and exhaust ducting and the vertical arrangement of the intake and exhaust ducts ensure that all eight cylinders are perfectly charged.
Patented variable intake manifold with two internal throttle flaps
The patented, dual-length intake manifold with two internal throttle flaps is a world first. Its task is to ensure a strong torque curve by lengthening the airflow distance at low engine speeds. At higher engine speeds the intake manifold switches to short airflow distances to achieve a high peak performance. The switching process is monitored by the electronic engine management system, vacuum-controlled depending on the engine load and engine speed, and imperceptible to the vehicle??????????????????????????????????????s occupants.
The interior of the light, die-cast magnesium intake manifold features two electronically operated throttle flaps which are adjustable within fractions of a second: they can be opened to their maximum in just 100 milliseconds, and the driver perceives this as extraordinary responsiveness. The air intake at the front of the vehicle is of dual-flow design; two integral hot film airflow sensors behind the air filters provide the engine electronics with the necessary information about the temperature and density of the intake air.
With the help of complex flow simulations the engineers at Mercedes-AMG have precisely configured all the intake ducting to meet the requirements of the large engine displacement and the resulting large air volumes.
Valve operation by bucket tappets, as in the racing engines
Another special feature of the new AMG V8 engine is the sophisticated valve train, which is also derived from the powerful AMG racing engines. The 32 valves in the cylinder heads are operated by bucket tappets. Their space-saving design allows a stiff valve train and therefore high engine speeds with large valve opening cross-sections, which in turn benefits output and torque. The large intake valves have a diameter of 40 millimetres, while their opposite numbers on the exhaust side measure 34 millimetres.
In contrast to a racing engine, the valve clearances are automatically adjusted by a hydraulic mechanism ??????????????????????????????????????? the customer benefits from long, variable service intervals and low costs.
Four continuously variable overhead camshafts
All four overhead camshafts are continuously variable over a range of 42 degrees. Both the intake and exhaust camshafts are adjusted as a function of engine load and engine speed, ensuring extremely high output and torque values and smooth idling, and especially low exhaust emissions. Depending on the engine speed, the valve overlap can be varied to ensure an optimal supply of fuel/air mixture to the combustion chambers and efficient venting of the exhaust gases. This variable camshaft adjustment is controlled electro-hydraulically and monitored by the engine management system; the system is driven by a duplex roller chain and intermeshing pairs of gear wheels.
Crankcase with bedplate and closed-deck design
When designing the crankcase, the engineers and technicians in Affalterbach opted for a sophisticated bedplate construction on the closed-deck principle, which is well established in the motor racing sector and is also used in the powerful, supercharged AMG 5.5-litre V8 engine of the Mercedes-Benz SLR McLaren. Amongst engine specialists, this configuration stands for a high-performance sporting engine which is uncompromisingly designed for the utmost robustness.
The lower section of the crankcase in the AMG 6.3-litre V8 engine is an enclosed unit, which particularly benefits the torsional rigidity of the engine. This type of construction also permits higher combustion pressures and reduces pulsation losses within the crankcase itself. This not only minimises the internal friction losses, but also produces more rigid bearing bridges for the crankshaft. More efficient integration of the oil scavenger also allows foaming on the part of the engine oil to be reduced. The crankcase is also equipped with special, cast-in steel components which improve the strength of the engine block even further, benefit the engine acoustics and ensure a reliable oil supply.
Unique process for cylinder wall coating
The engine block and cylinder heads are of cast aluminium-silicon alloys (AlSi7 and AlSi17) which represent the state of the art in terms of weight, thermal and mechanical resistance and long-term strength. The engine specialists at Mercedes-AMG use a particularly advanced process for the eight cylinder walls to produce a tribologically optimal surface, namely a coating applied by twin wire arc spraying (TWAS). The advantages of this technology are extremely low friction and wear accompanied by outstanding long-term durability. A considerably harder surface is achieved compared to conventionally coated cylinder walls. In fact the cylinder walls of the new AMG V8 engine are twice as hard as conventional cast iron liners ??????????????????????????????????????? a quantum leap for engine specialists.
No other series-production engine apart from the new AMG 6.3-litre V8 unit can boast such sophisticated technology - which means that once again, Mercedes-AMG has underlined its pioneering role in the development and production of innovative high-performance engines.
During the TWAS process, two metallic wires and an atomising gas are brought together in a coating unit. Passing a high voltage through the tips of the wires breaks the gas molecules down to form a plasma, and the wire tips begin to melt. The atomising gas removes molten metal from the wire tips and sprays these particles onto the cylinder walls to be coated, where they solidify. This is preceded by a high-pressure water jet which roughens the cylinder walls so that the individual sprayed particles adhere to the surface during the TWAS coating process.
The cylinder walls are then honed to achieve a perfect surface structure. During this process the micro-pores in the sprayed coating are partially exposed, which enables them to retain oil when the engine is running and ensure tribologically favourable lubrication of the pistons and piston rings.
This trailblazing process was developed in close collaboration between the DaimlerChrysler process engineering department and Mercedes-AMG, and has been brought to series production maturity for the first time in the AMG V8 engine.
Crank assembly optimised for the lowest possible inertia
The finely balanced crankshaft is designed for the highest stresses, consists of the high-quality forged steel alloy 42CRMo4V, rotates in five crankshaft bearings and features six counterweights for perfectly balanced masses. Torsional rigidity, long-term structural strength and inertia characteristics are also to the very highest standards. As a detail normally only found in racing engines, the counterweights feature heavy metal core plugs, which means that they can be made significantly more compact. As a result the complete crank assembly can be optimised for particularly low rotational and oscillatory inertia, which enormously benefits responsiveness and flexibility.
Two lightweight connecting rods forged by the cracking process are connected to each of the four crank pins. During this process, the utmost production precision is made possible by a predetermined breaking point created by a laser beam. Extremely close weight tolerances between the eight connecting rods are also ensured by precision machining. The same principle is also used for the cast, lightweight pistons. They are made from a durable high-temperature alloy. Pressure-controlled oil spray nozzles in the crankcase ensure optimal cooling of the highly stressed piston crowns.
Owing to the large overall displacement, a highly efficient oil pump with a high throughput is used in the new AMG eight-cylinder. Even at high rates of lateral acceleration, the intelligent arrangement of all the components in the oil circuit ensures a consistent supply of lubricant. The engine oil is cooled on a vehicle-specific basis, i.e. the sump and the arrangement of the coolers may vary. The cooling performance itself always remains constant.
Engine cooling on the sophisticated cross-flow principle
As in thoroughbred racing engines, the engine is cooled on the sophisticated cross-flow principle. This means that the eight individual cylinders have a uniform temperature by virtue of the homogenous coolant flow, thereby avoiding critical temperature peaks. The coolant flows from the exhaust side of the crankcase across the cylinder heads, then back to the thermostat and radiator via the collector on the intake side. The thermally highly stressed cylinder heads are also cooled according to this principle, which particularly benefits the operating life. Even the cylinder head bolts are included in the coolant circuit. This technology was developed with the help of complex flow calculations and perfected during an extended series of tests.
Variable coolant control for optimised friction
In addition the temperature of the coolant is variably controlled. In the interests of optimal in-engine friction and fuel economy, the temperature of the coolant can for example be lowered to 80 degrees Celsius under partial load. Under full load conditions the temperature is raised to 100 degrees within milliseconds to achieve the best possible engine cooling. The thermostat controlling the coolant temperature receives its instructions from the engine electronics.
Fuel supply monitored by a computer
The fuel supply of the AMG eight-cylinder is likewise computer-controlled and monitored. The fuel pressure is variably and instantly adjusted depending on the performance requirement and ambient temperature. The engine electronics execute commands from the accelerator pedal within milliseconds, leading to outstanding responsiveness. A high-pressure pump configured for the engine is integrated into the fuel tank.
Highly efficient engine electronics for every function
All engine functions are controlled and executed by a particularly efficient Bosch ME 9.7 control unit. Fuel injection, ignition, the variable intake manifold, camshaft adjustment and variable cooling are all controlled by the state-of-the-art engine computer, which also communicates with all the other onboard control units. The microprocessor has 10,000 different characteristic maps and functions in its memory, and is able to carry out up to 70 million individual operations per second.
To reduce the load on the engine control unit, the eight individual ignition coils have an integral electronic module known as an ignition amplifier at each cylinder. These ensure a strong ignition spark at all engine speeds and under all load conditions.
