Twincharging is a technology that does not get in the spotlight too often. But it has recently emerged from the archives and made its way back into production.
For those of you that are not familiar with the term, let’s explain what twincharging is, and why it is and was a big deal when it first came into production cars.
Back in the day, most cars had naturally aspirated engines. Superchargers were a rare occurrence, while turbocharged models were just a bit more common.
Eventually, the performance demands of the World Rally Car Championship led to the introduction of supercharged cars, while some models were running turbocharged engines.
Each system had its advantages and disadvantages, but turbos were mostly criticized for having “lag,” a phenomenon that is still manifested in some modern cars.
Superchargers did not have lag, but provided less boost and “robbed” the engine of power because they were run using a belt that was linked directly to the crankshaft pulley.
Eventually, a manufacturer developed a car that had both supercharging and turbocharging. The idea behind the concept was that the two systems would outweigh each other’s cons and provide a comprehensive benefit – more boost without any lag at any rpm. The first twincharged vehicle was born, and the year was 1985.
And so that brings us to the Lancia Delta S4 and “S4 Stradale”
The engine was also developed from the one used on the 037, but this vehicle had nothing to do with the Delta that was sold for the street. Peugeot, WRC rivals of Lancia at the time, applied a similar strategy with their 205 T16, which was far from the production car.
Long story short, the Lancia Delta S4 had to be sold to the public in a form close to the one used in WRC to allow homologation. Only 200 units were manufactured and sold under the name of Lancia Delta S4, but it was known as the “Delta S4 Stradale.”
It only came with 250 HP, but it had a space frame with steel tubes, fibreglass body panels, and a three-differential four-wheel-drive system.
Small production numbers have made the Delta S4 Stradale a collectible car from the moment the first one left the factory. Other homologation specials had the same fate, and this model had good reason to be a collectible because it was already as expensive as five Delta HF Turbo, which was the top-of-the-line Delta of the moment.
Meanwhile, the racing version was rated with a maximum output of 480 HP, but some claimed the engine was good for more than 500 HP. In the same year when the Italians launched the Delta S4 in the WRC, they tested a version that reached a maximum boost of five bars, and provided about 1,000 HP from the same 1.8-litre engine, but only for demonstration purposes.
The 1,000 HP engine was never raced, but the 480 HP car won five out of 12 WRC races it entered, with 15 podium finishes to remember. Its WRC presence ended after the tragic crash that killed driver Henri Toivonen and Sergio Cresto, his co-driver, at the 1986 Tour de Corse rally.
The 1980s went down in history as one of the most extreme and exciting eras in motor racing. Racing vehicles were producing insane amounts of power: from F1 to motorcycle GP racing, everything was thrilling to drive and required immense concentration and skill from the drivers. Perhaps the most radical series of this era was Group B rallying: dominated by cars with insane amounts of power racing down tight dirt-roads, it was surely a spectacle to see in its time. In this era, it was a feast for homologation specials: from Renault 5 Maxi Turbo to Audi’s S1 Quattro to Lancia’s own 037.
Perhaps the most famous of them all is the Delta S4 Stradale: if you’re looking for the ultimate homologation special, look no further than this Turinese beast. Developed jointly by Abarth and Lancia, it was a sensation: powered by Eng. Lombardi’s 1.8-litre four-cylinder that was both supercharged and turbocharged, it was a formidable fighter in racing trim, putting out no less than 500 bhp.
The S4 was also Lancia’s first four-wheel drive vehicle, implementing three differentials of which one is a viscous central differential that splits the torque at the 30% front and 70% rear. In order to satisfy homologation requirements, Lancia built no more than 200, with notable hardships to sell them: as by the end of the 1990s, some of them were still languishing in showroom deposits!
*Images courtesy RM Sothebys
**Article courtesy of autoevolution