The crazy thing about the twincharged four-cylinder in the Lancia Delta S4 is not that it makes 550 horsepower, but that it makes 550 horsepower in a mild state of tune. If you need to explain to someone the madness of Group B rally, this mid-engine, all-wheel-drive nutjob sums things up quite well.
In the Group B era, which spanned from 1982 to 1986, automakers went totally overboard developing monsters that pushed the limits of what was possible. Among a field of crazy cars, the Delta S4 was arguably the craziest, and a large part of why Group B was ended after the 1986 season.
In trying to offset turbo lag, Lancia bolted a supercharger to its 1.8-liter inline-four, which provided more low end power. As S4 owner John Campion says in this Petrolicious video, the motor made 550 horsepower in race trim, but was tested up to 1000 horsepower. It's theoretically always on boost, and despite its all-wheel traction, it's a hairy ride.
Sadly, it was a Delta S4 that was involved in one of , which led to Group B's cancellation. Henri Toivonen and co-driver Sergio Cresto careened of the road during the Tour De Course rally, and the kevlar-bodied car quickly burned to a crisp after apparently being pierced by a tree, killing the two drivers. Group B was banned for the 1987 season, and some manufactuers pulled out of the championship immediately.
The sport's governing body later found in an investigation that Group B racers like the Delta S4 were too fast, even for the best racers in the world.
Imagine that. A car deemed to quick for anyone to handle.
The Delta S4 stands as a fascinating monument, then. It represents a moment where racing lost its mind, with dire consequence.