The most extreme Group B car. Both supercharged AND turbocharged simultaneously, producing 250 PS road/600+ PS rally. Henri Toivonen and Sergio Cresto died in an S4 at the 1986 Tour de Corse, the accident that ended Group B. Only 200 road cars built for homologation.
History
The Delta S4 represented the absolute peak of Group B engineering. Abarth developed a twin-charging system where a Volumex supercharger provided instant low-RPM response while a KKK turbocharger delivered high-RPM power. The road car produced 250 PS; the rally car exceeded 600 PS.
The S4 shared almost nothing with the production Delta. The body was a composite shell over a tubular steel space frame. The engine sat behind the cabin in a mid-mounted position. All-wheel drive distributed power through a viscous coupling center differential.
On May 2, 1986, Henri Toivonen lost control of his S4 on the Tour de Corse rally. The car left the road, fell into a ravine, and caught fire. Toivonen and co-driver Sergio Cresto were killed instantly. The FISA immediately cancelled Group B.
The S4's death marked the end of the most extreme era in motorsport history. The technology was too advanced, the power too great, and the safety too minimal for cars racing on narrow public roads lined with spectators.
200 road cars were built for homologation. They are among the rarest and most significant rally cars ever produced. Values exceed EUR 500,000.
Production & Heritage
Value estimates are editorial assessments based on recent auction results and market trends.
Technical Specifications
Engine Details
Performance
Tags
Designed by Abarth / Lancia Motorsport
