The Audi S5: Engine and Running Gear

Source: Audi AG

Fascination no figures can express

The mighty eight-cylinder engine in the new Audi S5 is closely related to the high-revving mid-mounted engine of the new Audi R8 sports car. To suitably match the character of the grand tourer, in the S5 it develops 260 kW (354 bhp) at 7,000 rpm. This is combined with an extremely flat torque curve: the maximum torque of 440 Nm is already available from 3,500 rpm. But more importantly, at only 2,000 rpm drivers already have 85 percent of the full torque at their disposal. The effect is sheer exhilaration: no matter at what engine speed the driver presses the accelerator, the A5 charges forward with breathtaking pace.

Back to the figures: sprinting from stationary the S5 reaches the 100 km/h mark in 5.1 seconds, and in just 19.1 seconds it breaks through the 200 km/h barrier. As a matter of form, we should note that the top speed is governed to 250 km/h. However, no measurement can truly convey the outstanding free-revving character, the instant response, the continuous power build-up or the thrilling sound of the eight-cylinder engine.

High-performance in a compact form

This V8 with a displacement of 4,163 cm3 belongs to Audi’s family of modern V-engines, which includes units with six, eight and ten cylinders. They are all characterised by a cylinder angle of 90 degrees and a cylinder spacing of 90 millimetres. The four camshafts are driven by a two-stage chain timing drive mounted on the rear side of the engine, which allows easy maintenance.

The cylinder block of the V8 engine is cast from an aluminium-silicon alloy; the pistons and rings glide in the liners on the hard silicon crystals. Separate inserted liners are not necessary. This helps give the engine its compact dimensions and low weight. The oil sump and oil pump have been suitably designed to maintain a reliable supply of lubricant to the engine even at high lateral acceleration.

High torque and efficient combustion

The V8 draws its air through a newly designed two-stage variable intake manifold made of magnesium. Electric motors control the manifold length and the tumble, i.e. the movement of air in the combustion chamber, by means of flaps. The effect of these measures is high torque and efficient combustion.

The V8 naturally derives its enormous power potential from the innovative FSI direct injection technology with high compression and optimum fuel mixture formation. Two high-pressure pumps, driven by the intake camshafts, deliver the fuel to two interconnected chambers made of stainless steel and then on to the injectors. One of the most modern and fastest engine management systems on the world market controls the whole process – the Motronic MED 9.1.1.

Thanks to FSI technology, the combined cycle fuel consumption is just 12.4 litres, despite the engine’s enormous power potential. The exhaust system is manufactured from highly durable materials and the exhaust catalysts are integrated close to the engine. Tubular sheet-metal manifolds with air-gap insulation ensure that the gas treatment system quickly reaches its optimum operating temperature for maximum effectiveness. The two exhaust silencers each have a volume of 14 litres and are tuned so that only a well-modulated, pleasing sound emanates from the left and right tailpipes – powerful and sporty during acceleration, otherwise moderate and relaxing.

Every gear change a sheer delight

The engine power is transmitted by a six-speed manual gearbox. Its very short and precise throw action makes every gear change a sheer delight. In this new gearbox generation a dual-mass flywheel with an asbestos-free single-plate dry clutch is an integral part of the gearbox housing. As in the Audi A5, the differential and drive shafts in the S5 are positioned in front of the clutch. The advantages this offers are an exceptionally long wheelbase, a short front overhang and a good weight distribution. In combination with the Audi S5’s newly developed suspension, this helps set new standards in handling agility and precision.

The quattro permanent four-wheel drive, of course, provides perfect traction with variable torque distribution from its basic setting of 40 percent to the front and 60 percent to the rear axle. Within a fraction of a second, the asymmetrical dynamic system adjusts to driving situation prevailing at any one instant. It constantly delivers the perfect torque distribution and combines nimble sporty dynamics with a reliable and extremely safe self-steering effect at all times.

S sports suspension for firm road surface contact

To enhance the Audi A5’s overall performance, its especially designed S sports suspension is tuned for exceptionally dynamic handling. Its firmly tuned springs and dampers provide a direct and precise contact with the road and a cross brace has been added to give the solid front structure additional stiffness for high torsional loads. Nevertheless, the S5 also retains the ride and suspension comfort that make it a first-class touring car for long journeys. The lightweight five-link front suspension is bolted to the body via a rigid subframe and the trapezoidal link rear suspension is located by an elastically mounted wheel carrier.

The standard 18-inch cast aluminium wheels of S design with five parallel spokes are fitted with mighty 245/40 R 18 tyres. As alternatives, cast aluminium wheels of 5 twin-spoke star design or two-piece bolted cast wheels of 20-spoke design are available. They are both 19 inches in diameter and have 255/35 R 19 tyres. Whatever the choice, outstanding traction and directional stability are assured.

The heavy-duty 17-inch brakes – recognisable by their black painted brake calipers with S5 lettering at the front – always ensure precise deceleration. Audi S5 drivers also benefit from all handling dynamics functions of the ESP system such as ABS, traction control, electronic braking force distribution and electronic differential lock. Here again, though, the electronic stabilisation program ESP can be deactivated in two stages whenever the driver wishes to exploit the potential of the Audi S5 to the full on a suitable stretch of road.