The Audi Q7 V12 TDI - the world’s most powerful diesel passenger car

Produced in a patented casting procedure, GJV-450 is around 40 % more rigid and 100 % more fatigue-resistant than grey cast iron. This allowed the developers to reduce the wall thickness. The weight potential compared to conventional grey cast iron is around 15 %.

The crankshaft, forged from a chrome and molybdenum steel alloy, is held by an extremely rigid main bearing bracket made from cast iron reinforced by nodular graphite. The forged piston rods are cracked, whilst the forged pistons are made from aluminium.

Both cylinder heads are composed of three main elements. The lower section is made from a highly durable and light aluminium alloy where the intake and escape channels are integrated. The upper section guides the flow of engine oil, whilst both camshafts are stored within a reinforcing ladder frame.

The valves are actuated using low-friction roller cam followers with a compression ratio of 16:1. The engine characteristic swirl variations of combustion air were taken from the V6 and V8 TDI engines. The optimum swirl with respect to emissions and simultaneous high performance can therefore be set.

Like most Audi V-engines, the maintenance-free chain drive is located on the back of the engine in a space-saving arrangement. A new layout is used in the new V12 TDI. The chain wheel of the crankshaft locks into the gearwheel. From here two simplex chains drive the camshaft. Two further chains drive the oil pump and both high-pressure pumps in the common rail injection system.

Both new double stamped high-pressure pumps are part of the new common rail injection system developed by the specialists at Bosch. Both pumps amass up to 2,000 bar of pressure in the rails; only 1,600 bar was usually achieved up to now.

The piezo injectors, with their eight-hole jets, have also been radically updated.

An optimal spray is created in the combustion chamber through the high pressure. This in turn allows the ignition process to take place quicker and more homogenously, leading to a much better sound. The efficient combustion also improves performance whilst reducing emissions and fuel consumption.

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