taken from the Internet
Lancia built the Delta S4 for Group B Rally, more-or-less unlimited class of lethal little road warriors that stormed the European circuits from ’82 to ’86, when the series was discontinued due to safety concerns. The S4, a steroid-pumped variation on the Lancia Delta, the automobile that took the European "Car of the Year" Award in 1980, was originally concieved as the replacement for Lancia’s outdated and under-powered (for the class) 037 Monte Carlo.
The S4 was built on a mid-engine, tubular space frame equipped with a lightweight, full-time AWD drivetrain with a viscous LSD coupling that sent 30% of the power up front and 70% to the rear. It rolled out factory custom with a 1.8 liter, DOHC, 16 valve liter four-banger cranking out at least 470 ponies—I’ve seen estimates ranging up to 600 horse; an equine stampede of sufficient force to drive the S4 from nil to 60 in 2.9 seconds—on gravel.
The Lancia made it from hither to thither by dint of one of the most outrageous engines in the history of the WRC, NASCAR, WCW, or the NAACP. The S4 inline-four employed a Volumex turbocharger for low-end torque and a turbo for high-end speed. With twin intercoolers, a bypass valve, and centrifugal clutch that disengaged the Volumex unit at 4,000 revs, the S4’s drivetrain was a perfect fit for WRC stop-and-go courses. A bit too perfect, perhaps.
Group B racers generally weighed in at around 2,000 pounds and frequently cranked out as much as 600 horse at the flywheel. Pod-racing? Tame by comparison. Try piloting a 600 horsepower shoebox across a sinuous, craggy road with a few dozen other lunatics jockeying with you for precious space while thousands of bloodthirsty fans line the path screaming for their heroes and dreaming of blood. Tuskan Raiders aren’t stupid enough to get within blaster range of this kind of lethal asylum.
From its inception in 1982 to its final season in 1986, Group B proved to be one of the bloodiest classes in modern motorsports. Ironically enough, the series came to an end in large part due to a brewing media storm fueled by the untimely death of Delta pilot Henri Toivenen in ‘86. Toivenen, who won Monte Carlo that same year, crashed and burned at Corsica while at the helm of his S4 in what would prove to be Group B’s final season.
If you’re hunting for a road-ready S4, be prepared to do some serious sleuthing. Group B requirements demanded that manufacturers produce only 200 street-legal versions of their racecars per year to qualify. The detuned street S4—which still produced 250 bhp with the turbo/supercharger combo and top out at 140 mph, generally fetch about $100,000 on the open market, give or take.