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The Delta S4 Stradale may be road-oriented, but it's a rally hero with cutting-edge go-fast technology under the skin.
Founded in 1906, Lancia is undoubtedly one of Italy's most iconic automakers. Lancia Automobiles S.p.A is currently part of the Fiat Chrysler Automobiles (FCA) company, and it has stamped its place in history for producing iconic cars like the Aurelia, Fulvia, Stratos, and Thema. Besides defining the Italian automobile landscape, Lancia also made its mark as one of the world's most successful brands in the Group B World Rally Championships.
Related: 10 Group B Rally Monsters That Couldn't Be Tamed
The Group B era is lauded as the 'Golden Age of Rally,' the pinnacle of rallying that was everything from wickedly fast to intense, brutal, dramatic, and even deadly. Although Lancia realized great success with the 037, few models capture the rampant insanity of rallying in the mid-'80s better than the Delta S4. Group B regulations required competitors to produce a limited number of homologation specials, and Lancia's path to the rally competitions was the roadgoing Delta S4 Stradale. Read on to find out why we love the civilian-oriented Delta S4 Stradale.
FIA introduced Group B regulations after the 1981 season, which allowed for sophisticated, faster, and more powerful rally cars. Lancia managed to keep up with Audi's legendary Quattro rally car, but they knew they needed a four-wheel-drive rally car to sustain the rivalry. Thus, the iconic four-wheel drive Delta S4 rally car.
The Delta S4 was immediately successful, securing a respectable five wins in 12 WRC entries. Lancia based the roadgoing Delta S4 Stradale on its iconic Group B rally car, ensuring that it retained the same cutting-edge go-fast technology.
The Abarth engineers contracted to build the Delta S4 rally car were among the first in rallying to use computer-assisted programs to determine forces that each part would be subjected to during races. As a result, the small-diameter tubing used in the space-frame construction, the bodywork, and composite parts went through extensive aerodynamic and wind tunnel testing.
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The lightweight tubular space-frame construction was arguably the most advanced for a rally car at the time, and Lancia carried forth the formula to the roadgoing Stradale. Since the carbon/Kevlar composite used in the rally car was expensive, Lancia sourced the Stradale's fiberglass and epoxy body panels from Savio coachbuilders.
Lancia designed the Delta S4 Stradale with a blocky speed hatch design that echoed the hard corners and right angles popular in the '80s. The rally-spec Delta S4 featured an exaggerated aero design, and Lancia designers ensured they incorporated the same silhouette in the homologation model.
Lancia kept the Stradale true to its rally sibling, featuring a similar-styled waist spoiler on the hatch and intakes in the rear flanks. Although the front splitter got eliminated to promote everyday practicality, the roof deflector spoiler was retained as an option to enhance aerodynamic performance.
The Delta S4 Stradale was only a means to an end in Lancia's Group B rally ambitions. Still, it boasts surprisingly extensive standard equipment, no one expects from a rally homologation model. In contrast to the bare-bones racing Delta S4, the Stradale features a suede-covered steering wheel equipped with power steering and a factory electronic immobilizer.
Creature comforts include air conditioning, deep hand-stitched bucket seats, a storage pouch between the seats, real carpet, drilled aluminum pedals, high-performance gauges, and a trip computer. In addition to the strongly scented yet supple Alcantara, suede, and leather-upholstered interior, the cabin also gets sound deadening to improve interior ambiance.
The Delta S4 Stradale houses the same all-aluminum, longitudinally mid-mounted 1.8-liter inline four-cylinder as the rally car, but with a smaller K26 turbocharger. The lightweight yet balanced Abarth-designed engine was inspired by Formula One technology, boasting a rev range as high as 10,000 rpm.
Related: 10 Production Cars You Didn't Know Used Formula One Technology
Electronic engine control systems were not yet advanced at the time, so Abarth relied on release valves and pneumatic actuators to manage the engine. The engine also got a compression ratio of 7.0:1 and utilized electronic fuel and ignition injection by Weber-Magneti Marelli.
Rather than incorporating just a supercharger to boost the engine, Abarth also threw in a turbocharger, making the Delta S4 Stradale the first production car to feature twin charging. The supercharger is great at providing low-end power, but it tends to lose steam higher in the rev range. The turbo solves this issue since it makes plenty of peak power, allowing the supercharger to take over before the turbo gets up to speed at around 4,000 rpm.
This engineering marvel ensures that the supercharger and the turbo exchange boost duties via a bypass valve, providing the Stradale with a fat, seemingly endless torque curve stretching across the entire rev range. Additionally, twin-charging reduces turbo-lag at low rpms to deliver a better throttle response.
The incredibly complex twin-charging system provided the always-boosted competition Delta S4 with an official output of 480hp, although speculations suggest 600hp is more accurate. Due to the ungodly boost levels, Lancia had to put the street-legal Stradale on a leash, detuning its power to just 247 hp at 6,750 rpm and 215 lb-ft torque at 4,500 rpm. The Delta S4 Stradale hits 0-60mph in less than six seconds and has a top speed of 140mph.
However, these numbers could change with minor modifications. Lancia fitted the road going model with a 30-percent smaller KKK K26 turbocharger, while the sophisticated electronic ignition and injection systems control power delivery. The Delta S4 Stradale could realize almost double the power with a few adjustments.
The Delta S4 Stradale boasts a five-speed ZF manual transmission that sends power to all four wheels. Hewland developed the unique rally-oriented AWD system to take advantage of three differentials.
Related: Here’s Why All-Wheel Drive Is The Future Of Hypercars
The system features a centrally-mounted Ferguson differential that utilizes a viscous joint to distribute power. The central differential transfers 70-percent of the engine power to the rear limited-slip differential and 30-percent simultaneously to the open front differential.
Despite Group B's growing popularity, the rally car's racing success, and the technological prowess, the Delta S4 Stradale's 110.7 million Lira price tag was over-ambitious. The hefty figure could have bought five Delta HF Turbos in 1985, making the S4 Stradale the most expensive Delta in the lineup.
Unfortunately, S4 Stradales languished at the factory and in showrooms, explaining why some units were first registered in 1990. Abarth and Lancia sought to increase desirability through extras such as leather upholstery, different Alcantara shades, Corsa-style wheels, Potenziato performance upgrades, and alternative exterior colors besides the standard metallic cherry red.
Lancia and Abarth's production records from the 1980s might be non-existent, but it's no secret that they never achieved the 200-unit limited-production requirement for the Group B rally. The actual production number is well below 100, meaning the Delta S4 Stradale is undoubtedly one of the rarest and most desirable road-going Group B homologation specials in today's collector car market.
The Delta S4 Stradale holds significant provenance as a representation of Group B rallying at its most extreme and unadulterated, not forgetting the technological features it pioneered. Furthermore, the superior build quality and real-world appeal set the Delta S4 Stradale apart from any other Group B homologation special from the time.
Simon Kim has always been passionate about machines since childhood, and this has grown into an obsession well into adulthood. As an avid reader and creative content writer, he finds joy and fulfillment in sharing his love for cars and bikes with other machine heads. Currently, Kim seeks to deliver exciting and informative articles on HotCars. He enjoys music and art and dabbles in active sports and virtual gaming in his spare time.