The Lancia Delta S4 is one of the most revolutionary rally cars ever, a real racing monster that only the most talented drivers have been able to tame. The Group B didn't win the World Cup but came in anyway in myth, populating the dreams of who was a boy in the 80s.
The Delta S4 is the first Lancia with integral traction. The system, more sophisticated than that of the rival Audi four, features two mechanical self-locking differential and 30:70 torque distribution.
The most interesting feature of the Lancia Delta S4, however, is the engine (longitudinal mounted in the center rear position): a 1.8-liter, four-cylinder, 480 hp with double overcharging. The volumetric compressor, driven by the crankshaft, ensures good thrust at low regimes and compensates for the turbo delay (driven by exhaust gases), which intervenes later.
The car officially takes part in a race for the World Championships in the 1985 RAC (last season's test) and is surprisingly the world bringing home a double in Finnish sauce with Henri Toivonen and Markku Alén.
In 1986, the Lancia Delta S4 faces its only "complete" official season. In the first race of the year (Monte Carlo Rally), Toivonen rises again on the highest pitch of the podium, but the many reliability issues prevent the S4 from winning the World Cup.
The negative turn comes on May 2 at the Tour de Corse: the car driven by Toivonen (sailed by the US, Italian origin, Sergio Cresto) goes out of the way during the PS18 and crashes against some trees. Both lose their lives, Lancia withdraws the cars from the race and FISA (what was then the International Automobile Federation) decided to abolish the dangerous Group B since 1987.