Throughout the Group B period, many manufacturers attempted to push their machinery as far as allowed, towing the line of the FIA regulations, and no car was pushed further than the famous Lancia Delta S4; so far it inadvertently brought Group B to an end. Fitted with a 1.8-litre inline-4, the S4’s incredible engine was the first to be twincharged; simultaneously turbocharged and supercharged. The engine was quoted in period to develop around 500hp, yet one S4 engine was recorded producing 1000hp, more than enough in a 900kg car to develop it a reputation of being far too fast for drivers to keep up with, let alone control.
As the S4 shared little to no componentry with the road going Delta Integrale, Lancia were required to produce the Delta S4 Stradale, used to homologate the S4 rally car. Fitted with the identical 1.8-litre twincharged inline-4 accessible behind a clamshell rear engine cover, the Stradale produced a much more manageable 247hp. The S4 Stradale’s interior differed largely from its completely stripped out big brother, fitted with luxuries such as air conditioning, a trip computer, power steering and an Alcantara interior. Despite these amenities, the S4 Stradale’s weren’t slow by any stretch of the imagination, capable of sprinting from 0-60 in just 6 seconds and onwards to 140mph.