(latterly known as the V8 Vantage)
Almost as soon as the regular Virage coupe had entered production, development began on the high performance Vantage with the ultimate aim of a 186 mph (300 kph) supercar seating four in supreme comfort. Vantages from the past were usually the result of installing the optional, highly tuned engine into an otherwise unmodified chassis. From 1977, with the introduction of the V8 Vantage, the car developed into a more distinct model, easily distinguished from its lesser stable mates with visible aerodynamic enhancements and improved suspension and brakes. The previous two-valve AMV8 based Vantage delivered up to 435 bhp in big bore X-pack form, so the brief given to Arthur Wilson, the AM Powertrain Engineering Manager, was to achieve an output of or in excess of 460 bhp, then 480 and eventually 500 bhp. Very early on, instead of following the well tested route of increased capacity, Wilson investigated the prospect of supercharging. AM had never designed engines needing high revs to deliver power so the prospect of supercharging, which can deliver power and torque over a wide range was most attractive. The favoured self-contained Roots-style M90 units from the Eaton corporation could be designed to be an integral part of the engine rather than as bolt on units. By February 1989, the road parameters of the superchargers were agreed with Eaton which led to a decision to redesign the existing four-valve cylinder head completely. This resulted in a new casting incorporating redesigned porting, sintered valve seats and stainless steel valves. In addition, the Vantage crankcase was also a new casting designed to give increased stiffness to the main-bearing supports and a revised rear main oil seal. The camshafts, developed to prolong valve gear life, were also new. A first for the new engine was the use of thin-walled castings for a number of engine components while the catalysed exhaust system was of larger bore than used previously.
The finished engine featured twin superchargers, one for each bank of cylinders, and each had a capacity of 1.5 litres running at 1.8 times engine speed. Each was driven by a wide, multi groove, flat belt and dominated the space either side of the engine These were controlled through a by-pass system to reduce off-boost losses at tick-over: the turning of the superchargers could have otherwise consumed 40 bhp. The compressed air from the superchargers passed through water-cooled intercoolers to the engine and the fuel was supplied by a pair of Bosch sequential injection systems, one for each bank of cylinders. The engine was fitted with new lightweight pistons courtesy of Cosworth Engineering and engine management, used to control injection and ignition, utilised Ford expertise with the EEC IV system that was at the time also used by the Benetton Formula 1 team. As the power of the new engine increased, other modifications were needed to both suspension and brakes which increased weight and thus increased the demand for yet more power; not what would be described as a virtuous circle. The result of all this remarkable engine development was a peak output of 600 plus lb.ft of torque and 500 bhp which handsomely exceeded the target. Concerns for the safety of the transmission brought about a change in cam timings that gave a more acceptable flat torque curve peaking at 550 lb.ft and a ‘conservative’ 550 bhp. This was a remarkable improvement of more than 40 bhp per litre over the 1989 specification Virage engine.
Power was transmitted via a six-speed ZF gearbox as used in the Chevrolet Corvette ZR1 and final drive fitted with a limited slip differential unit. An automatic gearbox could not be specified for the Vantage in production although cars could be modified by Works Service once road registered.