Powertrain
Powertrain detail of the Audi V8 featured one of two all-new, all-aluminium alloy engines – both petrol engines, and both in V8 configuration with 32 valves (four valves per cylinder) with dual valve springs, and four overhead camshafts (2xDOHC). These new designs would set the pattern for future Audi-developed Volkswagen Group V8 engines. As well as using an all-aluminum alloy for the cylinder block (when the established material was grey cast iron), the camshafts were driven using a hybrid method. A rubber/kevlar toothed timing belt, driven from the front of the crankshaft drives only the exhaust camshaft in each bank. The inlet camshafts are then driven via a simplex roller chain from the exhaust camshaft - the right bank, (cylinders 1-4) at the rear of the engine, and the left bank (cylinders 5-8) at the front of the engine, immediately behind the timing belt. This method effectively reduced the complexity of the timing belt layout (known to be very complex on DOHC V engines), and as a result, required fewer components (idler rollers and guides), leading to easier and less costly maintenance of the timing belt and associated components. The intervals for changing the timing belts varied; the 3.6 V8 (PT) required changing every 90,000 kilometres (60,000 mi), whereas the 4.2 V8 (ABH) had a longer interval at 120,000 kilometres (75,000 mi). A thermostatically controlled electric cooling fan also became standard, replacing the engine-driven viscous fans on earlier cars. This not only provided forced airflow for the engine coolant radiator, but also for the smaller engine oil cooler.
Audi's now proven 'trademark' quattro permanent (or semi-permanent, dependent on gearbox type) four-wheel drive system was the only offering for the drivetrain. This normally distributes the engine torque as a 'default' 50:50 between front and rear axles, but can automatically dynamically apportion up to a bias of 20:80 to 80:20 front and rear. The automatic transmission utilizes a hydraulically controlled multi-plate clutch to apportion drive between front and rear axles, whereas the manual transmission variants utilize a Torsen type 1 Torque Sensing center differential.
The rear axle final drive unit (parts code prefix: 017; identification codes: AFV, AXZ) contains a Torsen type 1 Torque Sensing differential, instead of the more common hypoid open differential.
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