Lancia Delta S4

Lancia Delta S4 History

Sporting Supercars - Jeremy Walton

Although it won the first of the World Rally Championships it was designed to dominate - November 1985's RAC Rally-the Lancia S4 Delta might well go down in company history as a comparative failure.

This exotic machine, created around the framework of a production Delta hatchback, is one of the few recent Lancia-Abarth rally challengers not to scoop a World Championship title. This has less to do with the car's unique limited-production use of turbo-charging and supercharging, than with the abrupt curtailment, at the close of 1985, of Group B 'supercar' regulations.

Rules that allowed such 450-plus horsepower devices to bound along the rally tracks of the world were inevitably going to cause trouble. The tragedies of the 1985 season affected Lancia particularly, as two of its works personnel were killed in Corsica at the wheel of an S4: Henri Toivonen and Sergio Cresto.

The S4 Delta carries outward reminders of the Delta production car for marketing purposes, but when it was unveiled at an international press conference in December 1984, it could be seen that this lightweight three-door, mid-engined, four-wheel drive device had little in common with the steel-bodied five-door hatchback that had inspired its lines since development commenced in April 1983.

However, Lancia has since proved that the production Delta can win World Championship rallies, a 250 bhp version of the HF 4WD dominating the 1987 series after Group B was outlawed internationally at the close of 1986.

From the autumn of 1985, Lancia made the 200 S4s necessary to qualify for Group B competition, and a street version of this two-seater competition cocktail went on sale to the public. These cars are not nearly as powerful, nor as light, as the factory rally machines built on the S4 base, but they are still extremely exciting machines.

The S4 engine, displacing 1759 cc, is based on proven Abarth hardware and mounted longitudinally behind the front seats. In the 'production' cars its

KKK turbocharger and Abarth Volumex supercharger boost output to a maximum of 250 bhp at 6750rpm and 2141bft of torque. That sounds a lot from less than 1.8 litres, but the similar-sized motor of the Lancia-Martini rally cars was persuaded to yield a reliable 470 bhp at 8000 revs, plus more than 333 Ib ft of torque.

The aim of using both a turbo unit and supercharging was to overcome the lazy low-speed response of the turbo. The supercharger looks after the provision of extra punch below about 3500 revs, and the turbocharger supplies an increasing amount of boost at higher rpm.

The competition S4 used exactly the same twin intercooler principles, but the transition from supercharging to turbocharging took place at higher engine speeds, between 5000 and 6000 revs. Developing the engine's mechanically driven supercharger and the exhaust-impelled turbo to the point where power and torque delivery were harmonious was a complex challenge. Fiat-Lancia-Abarth engineers eventually met it successfully, but as yet nobody else has repeated the experiment...

Both competition and road derivatives of this extraordinary design have been based on a chrome-molybdenum steel-tube frame in a two-seater cabin, reinforced by box-section structures; these also serve as the main north-south chassis. Epoxy resins with glassfibre reinforcement provide the bulk of the external panels on the road car. The factory rally S4s used . flyweight carbonfibre composites for items such as the 'bonnet', slashing kerb weight from a roadgoing 2640Ib (1200 kg) to less than 2200lb (1000 kg).

Just as complex as the engine bay full of tubes, coolers and Marelli-Weber ignition/injection management is the 4WD system. The bulk of the central transmission is mounted forward of the four-cylinder engine and is packed with features including a five-speed gearbox, a Ferguson viscous-coupled limited-slip differential and epicyclic gears to split power thirty per cent front, seventy per cent rear. The back axle carries a conventional multiplate, limited-slip differential.

The description above applies to the cars sold to the public at more than £40 000; the works rally cars used a variety of traction enhancement devices and power splits to suit terrain from tarmac to sheet ice. Typical of the expensive lengths to which they would go was the fitment of titanium drive shafts in place of the road car's beefy steel units: every ounce counted.

Suspension and brake design is equally sophisticated and akin to a sports-racing car in the use of double wishbones and links. For rough road rallying plenty of cushioning is needed, so double I telescopic dampers are fitted on each side of the rear suspension, gas-damped by Bilstein on the competition S4s.

Because of the high power outputs achieved during this 'supercar' era of rallying, power steering became common equipment in top-flight cars. The Lancia uses pneumatic assistance for its rack-and-pinion steering that skips from lock to lock in just 2.5 turns. Even on the production cars, a quartet of massive 11.8-inch diameter disc brakes are deployed front and rear.

Pirelli supplied some very special 205/55 VR tyres that bear different tread patterns across their width to complement the car's suspension under varying loads. To accommodate those huge brakes, elegant Speedline alloy wheels of 16-inch diameter and 8-inch rim width are standard equipment.

Although the cars were created purely for competition, the public-sale S4s are trimmed in Alcantra cloth, and cope easily with everyday traffic conditions. The cabin boasts comprehensive instrumentation in the Lancia tradition, including a 260 kph (163 mph) speedometer and 9000 rpm tachometer, red-lined at 7500 for public road use.

Driving the car, it is initially the assistance of those two whining compressors, alongside double overhead camshafts and the sixteen-valve cylinder head, that make the greater impression. However, enduring memories are of the S4's astonishing grip and braking and its inspired acceleration - 0-62 mph (100 kph) in 6.0 seconds. Lancia reckon that the road car will reach 140 mph (224 kph), but more important is its ability tojink over tight Mediterranean trails at a glorious

7200 rpm, allowing 65 mph (104 kph) in second and 92 mph (147 kph) in third.

Riding alongside works drivers such as Markku Alen in the 470 horsepower rally car was something else. Inside that stark cockpit all you could do was watch in awe as impossible feats were achieved by a man and machine beyond mere mortal comprehension.