racingengineering:

Group B Lancia Delta S4 ~ 1986
1,759cc | 4-Cylinder | Supercharged and Turbocharged | 560+ horsepower

One of the most technologically advanced cars ever built, the Lancia Delta S4 was a purpose built racer tasked with the job of beating Audi and Peugeot for the Group B World Rally Championship. Using a mid-engine layout and a clever 4WD system to get the power down, the Lancia placed second in the Manufacturers’ championship in 1986, close behind Peugeot and well above Audi. The twincharged S4 powered driver Markku Alén to a second place finish in the Drivers’ Championship the same season, only missing the title after losing points on a technicality.

The S4 was only a Delta in terms of styling and name, simply to promote the Lancia Delta. Some aerodynamic changes were made to the body, while everything else was dramatically reworked to create a highly competitive Group B car. The body was constructed with a carbon fiber composite with quick repairs in mind; front and rear bodywork was fully detachable. The Lancia’s suspension was also drastically changed, featuring “long travel double wishbone suspension front and rear, with a single large coil over at the front and separate spring and twin shock absorber at the rear.”

The Delta’s 1.8L engine was designed to stay competitive primarily against Audi’s increasingly more powerful engines. The twincharging system would provide much more power at a much wider RPM range and vastly reduce turbo lag, while still reaping the high boost benefits of running a turbo. The car was said to be capable of reaching 100km/h from a standstill in 2.3 seconds, on gravel.

(Sources: “Group B: Too Fast To Race,” Wikipedia, Autozine.org)