Press Release
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.
