Lancia's 1,000-HP Masterpiece: The Twincharged Engine That Changed Motorsport Forever
In an era where forced induction was crucial for motorsport success, Lancia and Abarth crafted a monstrous 1,000-hp inline-four by ingeniously combining both a turbocharger and a supercharger, eliminating the drawbacks associated with each.
The Race to Innovation
Since the dawn of the internal combustion engine, engineers have relentlessly pursued higher performance, often through motorsports. Initially, increasing the number of cylinders or the engine's displacement was the go-to method. However, with the introduction of forced induction via superchargers and turbochargers starting in the 1930s, a new era of power was born.
Superchargers, driven mechanically to pump more air into the combustion chamber, held sway for years. But by the 1970s, advances in turbocharger technology started tilting the scales. Unlike superchargers, turbos use exhaust gasses' kinetic energy to compress air and boost the engine's power. However, turbo lag—an annoying delay in power delivery—remained a significant downside. Superchargers also had their own set of limitations, including decreased efficiency, higher fuel consumption, and added weight.
Determined to eradicate these performance bottlenecks, a joint team of Lancia and Abarth engineers came up with a groundbreaking solution during the 1980s. The result? An unprecedented engine that combined both turbocharging and supercharging, offering the best of both worlds.
A Monumental Collaboration
Around 1981, Fiat—Italy's automotive giant that owned the Lancia and Abarth brands—dominated the World Rally Championship (WRC). With victories from vehicles like the Lancia Stratos and Abarth-tuned Fiat 131, Fiat was a formidable force. Yet, by 1982, the competition sharpened with formidable rivals like Audi and Peugeot entering the scene with their revolutionary all-wheel-drive (AWD) and turbocharged systems.
Fiat responded with the Lancia 037, which utilized a supercharged inline-four. This machine only managed one victory in the 1983 season, prompting the Italians to head back to the drawing board. In 1984, they introduced an all-new Group B contender: the Delta S4.
Engineering Marvel: The Delta S4
Equipped with a solid AWD system developed with English company Hewland, the Delta S4 showcased one of the era's most advanced engines—a twincharged inline-four that promised unprecedented performance. Abarth engineers decided to innovate further by reducing the displacement of the existing Lamperdi Twin-Cam Fiat engine and reworking its forced induction system.
Rather than choosing between a supercharger and a turbo, they opted for both. The concept of twincharging was simple in theory but highly complex to execute. A Volumex supercharger operated at low to mid RPMs, seamlessly handing over to a Kühnle, Kopp & Kausch (KK&K) turbocharger at higher RPMs. This optimized the engine's performance across all speeds, eliminating turbo lag and maximizing high-RPM power.
On a test bench, the engineers pushed this twincharged marvel up to 1,000 hp with a turbo boost pressure of 5 bar (72 PSI). However, practical considerations for reliability resulted in a competition setup delivering between 480 and 290 hp.
The Most Dangerous Rally Car
Once the engine and AWD systems were in place, Lancia engineers took the 037's Chromoly steel chassis, upgrading it and designing a new body. Given the Lamperdi's 1.8-liter displacement, the car adhered to the 2,500 cc-class regulations, imposing a minimum weight of 890 kg (1,962 lbs). The engineers skillfully crafted lightweight carbon-Kevlar composite panels, resulting in an extremely light yet perilously fast machine.
The Delta S4 made a dramatic debut at the Lombard RAC Rally, ending the 1985 season with a victory, and continued its winning streak with another triumph at the Monte Carlo Rally in 1986. Despite its undeniable prowess, the S4 was involved in numerous accidents, the gravest of which claimed the lives of driver Henri Toivonen and co-pilot Sergio Cresto. This tragic event led to the FIA's decision to abolish Group B, cutting short the Delta S4's brilliant yet dangerous WRC tenure.
A Legacy of Innovation
To qualify for WRC, Lancia had to create road-legal versions of the Delta S4. Dubbed the S4 Stradale, these homologation specials were made from 1985 to 1986. Despite claims of producing 200 units, it's rumored that only 80-90 Stradales were actually manufactured. Powered by a Lamperdi engine with a smaller turbocharger, these road versions produced 247 hp but became the world's first twincharged production engines.
While twincharging didn't become the most popular forced induction method, it found its place in several production engines, notably the Volkswagen Group's 1.4-liter TSI inline-four. The Tipo 233 ATR 18S remains a testament to innovative engineering, embodying one of the most advanced race engines of the 1980s. Lancia and Abarth's daring combination of turbocharging and supercharging set a high benchmark and continues to inspire those who seek the pinnacle of automotive performance.