Vehicles - Lancia Delta HF Integrale and Lancia Delta S4

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The Lancia Delta S4 is a Group B rally car that competed in the World Rally Championship in 1985 and 1986, until Group B cars were banned from competition by the FIA. The car replaced and was an evolution of the Lancia 037 Monte Carlo. The S4 took full advantage of the Group B regulations, and featured a midship-mounted engine and all wheel drive for superior traction and handling. The car's 1759 cc four cylinder engine combined supercharging and turbocharging to reduce turbo lag at low RPM. Officially the car produced 550 horsepower (410 kW). Independent figures show the S4 could accelerate from 0 to 100 km/h (62 mph) on gravel in just 2.3 seconds.citation needed] An engine capacity multiple of 1.4 was applied to forced induction engines by the FIA and the choice of 1759 cc put the S4 in the under 2500 cc class which allowed a min weight of 890 kg (1,962 lb). The combined super/turbocharger system was a development of the 037 engine that produced 350 hp (261 kW) with a supercharger only. This was competitive with the Audi Quattro in 1984 which also had 350 hp (261 kW), but by the 1985 season Audi's S1 was homologated with 600 hp (450 kW). Consequently, a turbo had to be added to the S4 engine design to remain competitive.