Affalterbach, Germany, Mar 09, 2010

Development, trials and test bench technology: Endurance testing the exclusive high-tech powerpack

Development work on the new AMG 5.5-litre V8 biturbo engine began in 2006. The programme initially involved basic research for a synthesis of top-class performance, powerful torque and potential fuel savings. It quickly became clear that the spray-guided combustion principle exclusively developed by Mercedes-Benz should be combined with twin turbochargers.

The development work on the new eight-cylinder biturbo unit started with fundamental packaging research, analyses of basic mechanical functions, the oil and coolant circuits and the power characteristics with various intake duct and camshaft configurations, plus the definition of fuel injection quantities, fuel consumption and exhaust emission values – all these were studied by means of flow simulations and on the dynamic simulation test benches at Mercedes-AMG. Nine of the very latest, high-tech test benches are available in the Mercedes-AMG test bench laboratory, which was taken into commission in 2004; engines with outputs exceeding 735 kW (1000 hp) can be dynamically tested in this facility.

These test facilities are able to simulate any road and environmental conditions to reproduce any conceivable type of operation. Cold or hot starting, mountain passes, stop-and-go traffic or fast laps on the North Loop of the Nürburgring – the engines were required to give their utmost. Even the intake air temperatures and densities can be varied by computer control, and the engines can be alternately filled with hot and cold coolant. Fuels of different grades are also available.

The goal of the detailed bench tests was to verify the performance of all the engine components, including the peripheral units. All the measurement data for the engines examined were systematically compared, and evaluated using reproducable test methods. To ensure the very highest quality standards, the new V8 engines themselves were required to undergo 17,000 hours of endurance testing.

In conjunction with the AMG SPEEDSHIFT MCT 7-speed sports transmission, the final test was a 4000-hour endurance test on a special engine/transmission test bench.

Extensive trials in every climatic zone on earth

At the same time the first test engines had to prove their worth in practical trials. Whether in the icy cold of northern Sweden, the merciless heat of Death Valley (USA), lapping the high-speed circuits in Nardo (Italy) and Papenburg (Germany) or in stop-and-go traffic in inner-city Stuttgart – the standardised test programme of Mercedes-AMG includes all climatic zones and route profiles. At the same time it makes the very highest demands on the day-to-day practicality, reliability and long-term durability of the new engine/transmission combination. All in all, the different AMG test vehicles covered around 700,000 kilometres of mixed endurance testing on the roads.

Special tests for the new start/stop function

The test engineers paid particularly close attention to the operation of the new start/stop function, for which purpose they undertook extended journeys in the stop-and-go traffic of various major 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 vital further development of the control software, and its constantly necessary application to the different onboard systems.

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