The Complete History of the Lancia Delta S4

The Lancia Delta S4 was possibly the greatest interpretation of the insane Group B Rally rules of the 1980s. With its twin-charged engine and four-wheel drive system, the Delta S4 would go on to claim a number of wins before the Group B series was disbanded.

To celebrate this incredible car we are going to be covering its entire history and some important facts you need to know about it. We have broken this article up into a number of different sections, so feel free to use the table of contents below.

The History of the Lancia Delta S4

Along with the article below, we have also created a video on the complete history of the Lancia Delta S4. Check it out below!

How it Started

Prior to the 1980s, rally cars were limited to 2WD and manufacturers such as Lancia, Ford and Fiat dominated the sport. Audi showed little interest in rallying until the international rally regulations changed to allow four-wheel drive cars to compete. The company had been working on a high-performance four-wheel drive car known as the Quattro from 1977, and the changes made to the rules meant that it could now compete.

Make sure you check out our article on the Audi Quattro here.

The Quattro originally competed as a development vehicle until it was raced on a formal basis from the 1980 Janner Rally. Audi’s four-wheel drive system gave the Quattro a unique advantage over its competition and the car would go on to take its first win in the hands of Hannu Mikkola at the 31st International Swedish Rally.

Following the 1981 season, the FIA introduced a new set of regulations known as Group B. The Group B regulations meant that rally cars could now be built more powerful, sophisticated and faster.

Lancia introduced their 037 Group B Rally car at the Rally Costa Smeralda in Italy, while Audi continued to develop the Quattro. Audi would go on to dominate the 1982 season with the Quattro, but Lancia managed to claim the title the next year with the 037. Despite winning the 1983 season with the rear-wheel drive 037, Lancia knew they needed a four-wheel drive rally car of their own.

Developing the Delta S4

The task of creating a new rally car would be given to Abarth, even though they had no prior experience with four-wheel drive systems. Dubbed the “SE038” project”, the car would feature a fully tubular space-frame construction that was heavily inspired by the 037’s one. Like the 037, the new car would also be mid-engined for improved weight distribution. (source Jay Auger, Rally Group B Shrine)

As Group B regulations had increased rallying’s popularity immensely, Lancia decided that the new car should be based on the Delta. The Delta was a front-engined, front-wheel drive car that shared almost nothing in common with the final rally Delta S4 (Supercharged 4WD), except for the grille and the front windscreen.

To complement the new design, Abarth decided to create a new engine that was inspired by Formula One technology. It was incredibly lightweight but balanced as well, with a rev range up to 10,000 rpm.

Abarth also decided to supercharge and turbocharge the engine (also known as “double supercharging” or “twin-charging”) to improve torque access across the rev range and give the car more power. Additionally, twin-charging also helped to reduce turbo-lag at low rpms and give a better throttle response on tight rally stages.

Read more about how twin-charging works here.

As electronic control systems were not advanced enough for such a complex system at the time, Abarth had to rely on pneumatic actuators and release valves.

Abarth managed to complete a prototype version of the “233 ATR 18S” engine before the first rolling chassis of the Delta S4 was even complete. For this reason, Abarth’s engineers quickly modified the rear section of an 037 to accommodate the prototype engine. The 037/S4 prototype was a bit of a monster and was nicknamed “Mazinga” after the the Japanese anime character.

Test drivers for the project reported a significant increase in both horsepower and torque but discovered problems with the exhaust system and heat management. In addition to this, they also reported that the engine was too powerful for the rear-wheel drive chassis, making it exceedingly difficult to drive. This information confirmed to need for a sophisticated four-wheel drive system that could handle the engine’s immense power.

Due to the S4’s 1759 cc engine and twin-charged induction system, it was placed in the 2000 – 2500 cc class (FISA multiplication factor of 1.4 for forced induction vehicles). This meant that the S4 could weigh as little as 890kg (1962 lbs). The Abarth engineering team went to enormous lengths keep the S4’s weight as close as possible to the 890kg limit.

A number of safety concerns were raised over the engineering team’s use of thin bodywork panels, composite parts for much of the car, and small diameter tubing for the space frame construction. However, Abarth’s engineers were some of the first in rallying to use computer aided programs to work out the forces that parts would be subjected to. Due to the tests carried out on these programs, Abarth significantly increased the chassis’ strength over the original design.

Extensive tests were done on the prototype S4 while it was disguised as a military vehicle. Abarth discovered that the car could weigh as little as 890kg, but the chassis and bodywork were too weak to withstand the forces of repeated rally use.

Because of this, the team had to add reinforcements to both aspects of the S4 to make it reliable enough to compete in rally events. The result of this strengthening was a weight increase to 950 kg (2094 lbs) for tarmac events and 1050 kg (2314 lbs) for dirt rallies. (source Jay Auger, Rally Group B Shrine)

Abarth carried out extensive wind tunnel and aerodynamic testing of the S4’s bodywork. This sort of testing program was rarely seen for a rally car and lead to the vehicles unique look. The final bodywork was manufactured out of a lightweight carbon/Kevlar composite that was rather expensive at the time. To save weight, Abarth made the doors hollow. They consisted of a thin Kevlar outer shell and composite acrylic windows.

To access all the components of the car, both the rear and front sections could open up in a “clamshell” fashion and the team mechanics could easily and quickly remove all of the bodywork if need be.

The rear of the Delta S4 features large side scoops that feed air to the intercoolers for both the supercharger and turbocharger. The bonnet features a vent with a Gurney flap that serves two purposes – one is to help cool the radiator and the other is to allow for quicker access to the spare tyre. On the top of the S4 there is a roof scoop that feeds air to both the intake and oil cooler.

Aerodynamic performance was increased by fitting a large flexible air dam at the front and a deflector spoiler on the roof. The spaceframe construction was considered to be the most advanced for a rally car at the time.

The Delta S4 Goes Rallying

Lancia and Abarth managed to get the Delta S4 homologated for the RAC Rally, the last event of the season. The car managed to achieve an incredibly 1-2 finish in the hands of Henri Toivonen, Neil Wilson (co-driver), Markku Alén, and Ilkka Kivimäki (co-driver), ahead of the MG Metro 6R4 driven by Tony Pond.

Lancia, Toivonen, and the Delta S4 had a strong start to the 1986 season at the Monte Carlo Rally, claiming first place just ahead of the Peugeot 205 Turbo T16. This result confirmed that the S4 was a serious contender for the WRC title and it broke over a year of Peugeot dominance in the sport.

Following Monte Carlo, Markku Alén and co-driver Ilkka Kivimäki would take second place in the Delta S4 at the Swedish Rally, just behind the 205 T16.

While the Delta S4 proved to be a formidable contender, it was not without its problems. The car often had to undergo chassis repairs and full rebuilds after each rally, making it unsuitable for rougher endurance events. This problem came to a head when Lancia decided to use the old rear-wheel drive 037 for the Safari rally.

In addition to the chassis problems, Lancia’s drivers also complained that the cabin of the S4 would get extremely hot due to heat radiating from the engine just behind them and the transmission between the seats.

Another problem with the S4 was that the throttle pedal could get stuck on the composite floor, making it impossible to drive. Additionally, the composite material would crack after repeated abuse.

The next event was the Tour de Corse in May. To improve performance, Abarth and Lancia put the S4 on an extreme diet, removing as much weight as possible. This extensive weight minimising philosophy ultimately lead to disaster when Henri Toivonen and co-driver Sergio Cresto crashed during the event.

The car they were piloting flipped over a stone wall, rolled down a rocky bank, hit some trees and then caught fire. There were no witnesses close enough to see the tragedy, but there were a number of reports of an explosion and flames shooting up over the treeline.

The cause of the explosion was due to tree branches puncturing the thin aluminium fuel tank that was located under the front seats. A hot mechanical part then came into contact with the fuel, igniting it. To reduce weight, the Lancia rally team had removed the skidplates making the fuel tank more exposed to outside elements.

Prior to this terrible event Toivonen had set the fastest stage times for the rally, despite reporting that he was not feeling well. Toivonen was considered to be the only driver truly capable of taming the mighty S4 and driving it at the absolute limit. Toivonen and Cresto’s crash at the Tour de Corse is often considered to be the main reason for the cancellation of the Group B regulations.

Despite the loss of Toivonen and Cresto, Lancia decided to continue the season. Miki Biasion and co-driver Tiziano Siviero took second at the Acropilis Rally in June and the car would finish 2-3 in New Zealand.

Following this result, the Delta S4 proved to be dominant at the Rally Argentina with Biasion and Siviero taking first place with Markku Alén and Ilkka Kivimäki in second. The Delta S4 would go on to take third at the 1000 Lakes Rally in Finland and then first, second, and third at the Rallye Sanremo in Italy.

The Sanremo rally was one of the most controversial events of the season when the entire Peugeot team was disqualified for using illegal side skirts. However, the cars were later proven legal by the FIA, and the Italian organisers were blamed for not allowing French Peugeots to take the win ahead of the Italian Lancias. Eventually, the FISA cancelled all points for the event, drastically altering the final outcome of the championship.

At the next event, the RAC Rally, the Lancia Delta S4 managed to claim second place, just behind the 205 T16. However, the S4 managed to place first at the next and final event of the season, the Olympus Rally.

By the end of the season, Markku Alén was crowned champion, but this would later change when the Sanremo Rally points were dropped. Alén and Lancia lost the world championship only 12 days after they were crowned champions, and the Delta S4 would end its WRC career.

If not for the tragic events at the Tour de Corse, Toivonen could have been crowned champion and Lancia would have almost certainly won the manufacturers title. A small consolation came for Lancia when they won both the European and Italian Rally Championships with Fabrizio Tabaton and Dario Cerrato behind the wheel.

Following the 1986 season, Lancia tried to find official uses for the incredible S4. One car made its way into autocross competition, taking a win in the hands of a factory test driver. Another S4 entered the 24 Hours of Chamonix snow-ice race, taking second place.

While the Delta S4 would not be entered in any other events by Lancia, a number of privateers successfully raced the car in various different motorsport disciplines such as hill climb, rally cross, rally sprints, and autocross.

Despite being entered in only one single season of the World Rally Championship, the Delta S4 would lead to the development of the Delta HF Integrale (Make sure you check out our “Integrale Buyer’s Guide and History” article. The Integrale was an instant success and it would go on to win six WRC manufacturers titles, making it the most successful rally car of all time.

How Much Power Did the Lancia Delta S4 Produce?

The 1759 cc twin-charged engine fitted to the Delta S4 was a seriously powerful engine. Officially, the Delta S4 produced around 450 horsepower, however, many rally insiders believe that it was actually closer to 550 horsepower.

Lancia and Abarth had even more power planned for the S4. It is rumoured that in early 1986 Henri Toivonen drove two test laps of the Formula One Estoril circuit in Portugal with an 800+ horsepower version of the S4.

This monster vehicle managed to come within a few seconds of the qualifying times set by F1 cars at the time. Ninni Russo, Lancia’s rally team manager at the time, somewhat confirmed the rumour but also stressed that Toivonen was an exceptional driver who had prior Formula One experience.

Markku Alén also stated that he was given an S4 with an upgraded engine that could produce up to 750 horsepower for the 1986 Olympus Rally. During independent tests it was discovered that the Delta S4 was the fastest accelerating Group B rally car with a 0-100 (62mph) time of 2.4 seconds on tarmac.

Lancia Delta S4 Rally Specifications

Delta S4 Chassis Numbers

Below we have listed the different chassis numbers of the Delta S4 rally car and their history.

Chassis 201 TO 73077E –  Was the sixth prototype S4 built by Abarth. It Made its official debut with Markku Alén at the 1985 1000 Pistes Rally and the Rally Colline Di Romagna. During these two events, the car was run in prototype form and wore the number plate TO 2664. Once the Delta S4 was homologated, this car was only used as a back vehicle at the Swedish Rally and the Memorial Bettega.

Chassis 202 TO 77889E – This car was used by Henri Toivonen at the 1985 RAC Rally, which he won. The event was the Delta S4’s official WRC debut and it showed the world that the car was a serious contender. Following the RAC rally, Toivonen used the car as a backup at the Monte Caro Rally, Swedish Rally, and Costa Smeralda. Following this, Roberto Rosselli used the car in Slaloms.

Chassis 203 TO 77891E – Was built for Fabrizio Tabaton of the Grifone Esso team for the 1986 season. The car was used at the Sanremo, Elba, Maderia, Targa Florio and Principe De Asturias rallies. In addition to this, chassis 203 was used in the Italian TV series Voglia Di Vincere, and was raced in autocross and slaloms. It won the 1988 European Autocross Championship and competed at the 1990 Chamonix 24 Hour Race.

Chassis 204 TO 77890E – This car was built for Toivonen for the 1986 WRC season and competed at the Costa Smeralda Rally, the Swedish Rally, and the Rallye de Portugal. Mikael Ericsson would then use the car at the Acropolis Rally and Jorge Recalde would use it for his home event in Argentina. Following this Chassis 204 was used as a backup vehicle for Alén and would go on to win the 1991 European Autocross Championship.

Chassis 205 TO 81694E – Alén used this Delta S4 at the 1985 Algrave Rally. It would later be used as a test vehicle and then as Kalle Grundel’s backup car for the 1000 Lakes Rally. The car also made numerous trips to Fiat’s wind tunnel for development purposes.

Chassis 206 TO 76794E – Alén drove this S4 at the Tour de Corse and the Acropolis Rally. Following this, Mikael Ericsson drove it at the Rally New Zealand and the 1000 Lakes Rally. Miki Biasion then used the car as a backup vehicle at the Sanremo rally.

Chassis 207 TO 76797E – Driven by Markku Alén at the 1985 RAC Rally. Following this it was used by Fabrizio Tabaton at the Ypres, Halkidikis, and Antibes rallies. The car then won two European Autocross Championship’s in 1987 and 1988 with Gian Battista Rosella behind the wheel.

Chassis 208 TO 77892E – Made its first appearance in 1985 at Saint Remy to test Pirelli’s snow tyres for the Monte Carlo Rally the next year. The Jolly Club rally team raced the car at the 1986 Mille Miglia and the Costa Smeralda with Dario Cerrato at the wheel. The Lancia rally team kept chassis 208 as a backup vehicle for the entire 1986 season. It was also tested by the Italian magazine Quattroruote, and was entered in the 1987 and 88 Campionato Italiano Velocita Montagna.

Chassis 209 TO 73073E – Miki Biasion first used Chassis 209 to claim the Rally Argentina, his first World Rally Championship win. The car was then used as a backup for Alén at the 1000 Lakes Rally before entering the Superga Slalom, the Catalunya Rally, and the Rally Di San Marino. Gerard Parquet then purchased the car and used it for hillclimb events.

Chassis 210 TO 77893E – Dario Cerrato used this car at the Rally Isola d’ Elba, Targa Florio, Limone Piemonte and the Rally Della Lana. Following its period at Jolly Club, Chassis 210 was entered in the 1988 French Rallycross championship, and the 1989 and 1990 European Rallycross Championship. It also won the 1990 Chamonix 24 Hour rally.

Chassis 211 TO 73074E – Toivonen drove Chassis 211 at the Tour de Corse Rally. It was destroyed by Fiat after his and Sergio Cresto’s terrible accident.

Chassis 212 TO 73075E – Is a bare chassis that was used to manufacture the carbon molds for the ECV. The ECV was a prototype Group S rally car that was developed to replace the Delta S4 for the 1988 WRC season. We have more information on the ECV further on in this article.

Chassis 213 TO 73076E – Was originally used as a backup and test car for the Argentina Rally. It was driven by Pianta and Biasion. Later, the car featured on the Italian TV program, La Voglia Di Vincere.

Chassis 214 TO 76795E – Miki Biasion drove this Delta S4 at the Rallye de Portugal, the Tour de Corse and the Acropolis Rally. Later it would be used by Markku Alén and Biasion at the Rally Argentina and the Sanremo rally. Ericsson used the car at the RAC rally at the end of the season, but had to retire due to engine problems.

Chassis 215 TO 81693E – This Delta S4 won the Monte Carlo Rally with Henri Toivonen at the wheel. It would later be used as a backup car for Toivonen at the Rallye de Portugal. Following this, Alén and Ericson would get it as a backup in Corsica and at the Acropolis Rally. Once the car retired from WRC events it would be entered in the 1988 European Autocross Championship where it came second. It won the championship the next year.

Chassis 216 TO 73078E – There is no history of this chassis number racing.

Chassis 217 TO 73079E – Biasion and Cerrato used this car as a test vehicle before the Messina Rally.

Chassis 218 TO 73080E – Was used as a show car at the 1986 Torino Motor Show and did not compete in the WRC.

Chassis 219 TO 81696E – Miki Biasion first used this Delta S4 at the 1986 Monte Carlo Rally. Unfortunately, he had to retire from this event due to a crash. Following this Chassis 219 was used as a test vehicle in Portugal and as a backup car at the Acropolis Rally.

Chassis 220 TO 81697E – Markku Alén drove Chassis 220 at the Swedish Rally and Rallye de Portugal before using it as a backup at the Acropolis Rally. Fabrizio Tabaton also used the car as a backup at the Ypres Rally and Henri Toivonen used it as a test vehicle in Corsica. The car was entered in the Rally Di Messina by the Jolly Club Team with Dario Cerrato behind the wheel. Following its rally career, Chassis 220 was used in hillclimb events.

Chassis 221 TO 77894E – This Delta S4 was used by Alén at the first edition of the Memorial Bettega in 1985. Following this, Fabrizio Tabaton and the Grifone Team competed in the first rounds of the European Rally Championship with the car. Chassis 221 was also used as a backup vehicle at the Elba, Madeira, Antibes and Halkidikis rallies. Gustavo Trelles took the 1988 Spanish Gravel Championship in the car as well.

Chassis 222 TO 90679E – This car was the first of the lightweight Evo chassis’s and was driven by Markku Alén at the Rally New Zealand. Dario Cerrato and the Jolly Club Team then used it at Piancavello, Sanremo, Valle d’ Aosta and the Monza Rally. Later it would be entered in slaloms and hillclimb events.

Chassis 223 TO 90680E – Alén first used Chassis 223 at the Rally Argentina and took second place with the vehicle. The car was then piloted by Kalle Grundel at the 1000 Lakes Rally in Finland. Following this event, A.R.T purchased the vehicle and Paolo Alessandrini drove the car at the Olympus rally. Chassis 223 was also used at the 1987 and 1988 Pikes Peak Hillclimb events, and was entered in the 1987 Chamonix 24 Hour Rally, Rally Isla De Tenerife and the Rally Dei Castelli. Finally, Gustavo Trelles used the car in the Spanish Gravel Championship from 1988 to 1990.

Chassis 224 TO 90681E – Miki Biasion drove this chassis at the Rally New Zealand before giving it to Markku Alén for the 1000 Lakes Rally in Finland. Alén also used it as a backup at the Sanremo rally and it featured on the Italian TV Series La Voglia Di Vincere.

Chassis 225 TO 33874F – This Delta S4 was driven by Alén at the controversial Sanremo rally and the Olympus Rally. The car was then sold to Jolly Club where it was used in the 1987 Spanish Gravel Championship.

Chassis 226 TO 19737F – Like Chassis 225 above, this Delta S4 was driven at the controversial 1986 Sanremo rally (Miki Biasion was at the wheel). Markku Alén then drove the vehicle at the RAC Rally later that season. The next year, this Delta S4 was driven in the European Rallycross Championship with Matti Alamaki at the wheel. Additionally, the car was taken through the Valkeakoski stage on the 1987 1000 Lakes Rally with skier Patu Leppälä strapped to the roof. Following this, Chassis 226 was raced in some British Rallycross races in 1988 before being entered in the 1989 European Rallycross Championship.

Chassis 227 TO 52127F – Miki Biasion used this chassis at the Memorial Bettega in 1986 and also used it with Bruno Saby at the Chamonix 24 hours the following year. In 1988, Saby drove the car at the French Rallycross Championship with the backing of Lancia France. A number of upgrades and modifications were made to the car for the championship.

Chassis 228 TO 52126F – Markku Alén drove this Delta S4 at the 1986 Memorial Bettega. Following this it was used as a test vehicle for the SE040 with a CVT transmission.

Lancia Delta S4 Stradale

To compete in the World Rally Championship, Lancia had to produce a number of road-going versions of the Delta S4 rally car. Between October 1985 and 1986, Lancia built 200 examples of the Delta S4 Stradale. When the Stradale was launched it was priced at around 100 million Lira, five times more than the most expensive Delta of the time, the HF Turbo.

Like the Rally S4, the Stradale was significantly different to the standard Delta model. The only components that it shared were the rear tail lights, the front windscreen and the grille. Lancia raided the Fiat parts bin for the interior components of the car and the wheels were manufactured by Speedline.

While Abarth manufactured the rally Delta S4, Lancia built the Stradale in partnership with Italian firm Savio. The Delta S4 Stradale made its official debut at the 1985 Turin Motor Show.

Lancia kept the Stradale true to the rally car. It retained the mighty mid-mounted twin-charged engine and spaceframe construction. While the engine was the same as the rally S4, power was reduced to 250 horsepower and a smaller K26 turbocharger was fitted. For those that wanted more power, some minor modifications and tuning could double the engine’s power output.

On the inside, the Stradale featured alacantra seats, sound deadening and other creature comforts such as air conditioning. To save costs, Lancia produced the body panels out of polyester resin rather than the carbon/kevlar material that was used on the rally car.

As the Stradale didn’t need as much engine and oil cooling, Lancia decided to block off the roof scoop. This also gave the car better visibility out the back, making it easier to drive on normal roads.

The Stradale did have its problems. The chassis lacked the reinforcements of the Corse version and was not as strong. This meant that it could break under hard use. Additionally, the car suffered from a weak clutch that was prone to overheating and the engine oil had to be checked regularly due to a leak issue with the supercharger compressor.

While Group B rules stated that 200 units had to be produced for homologation requirements, Lancia may have fudged the numbers a bit. In the latter stages of the Group B series, the FISA gave manufacturers a bit more leeway by allowing evolution cars to be homologated first.

It is not known how many Stradale cars were actually produced, but there have been claims from anywhere from 45 units to 150. Many of these Delta S4 Stradales have been converted into racing (Corse) versions by their owners. This makes the standard S4 Stradale one of the most collectible and rarest cars in the world.

Lancia Delta S4 Stradale Specifications

Lancia ECV

The ECV (Experimental Composite Vehicle) was a prototype Group S rally car that was designed to replace the Delta S4 in the World Rally Championship for the 1988 season. However, Group S cars were banned at the same time as Group B cars. Lancia went on to develop the Group A Lancia Delta after the ECV project.

The main goals of the ECV were to provide better engine and gearbox performance and reliability. Additionally, the car would feature a redesigned suspension layout at the front and better aerodynamic efficiency. Improved handling was achieved by shifting more weight towards the car’s centre of gravity.

Instead of a twin-charging the 1759 cc engine, Abarth planned to use two turbochargers that would boost power to 600 horsepower at 8000 rom and 398 lb-ft of torque at 5000 rpm. To keep weight down, the ECV was crafted out of carbon/Kevlar composite materials.

Lancia Delta S4 for Sale

Both the rally and road versions of the Delta S4 have become some of the most collectible cars in the world. We have listed some that have sold in the past to give you an idea of how much they are worth.

1985 Lancia Delta S4 Stradale – RM Sotheby’s 11 – 12 April 2019

This Lancia Delta S4 Stradale sold for a mind bending €1,040,000 (US$1,169,650) in April 2019. It had only travelled 2,200 km since new and was accompanied by all its original books and tools. The car was originally sold in Italy before moving to France and then Germany. It then wound up back in its home country of Italy.

Miki Biasion’s Lancia Delta S4 – 2016

In 2016 Miki Biasion’s backup car for the 1986 Rally Argentina came up for sale. The car was still wearing the iconic Martini livery and was completely unchanged from its 86 specification. No price was advertised but it expected to sell for around £320,000 (US$400,000).

Top Eleven Lancia Delta S4 Facts

1. The Delta S4 Stradale was the first twin-charged production car to be sold. Manufactures had sold turbocharged and supercharged vehicles, but nobody had combined the two for a production car.
2. It won the 1986 WRC season for 12 days. Markku Alén and the Lancia rally team were crowned champions for the 1986 WRC season before it was taken away from them. This was because all points for the Sanremo rally were dropped after the Peugeot 205 T16 was deemed legal.
3. Henri Toivonen was seen as the only driver who could really tame the car. Toivonen was regarded as an execptional driver and the only one who could truly drive the Delta S4 at its absolute limit.
4. An 800+ horsepower Delta S4 is rumoured to have been tested by Toivonen at the Formula One Estoril circuit in Portugal. During these tests it was believed that the S4 set lap times only a few seconds shy of Formula One cars of the period.
5. The Delta S4 claimed first and second at its first official WRC event. Henri Toivonen and Markku Alén came first and second respectively at the RAC Rally in November 1985.
6. Only two parts of the Delta S4 were shared with the car it was based on. The only two parts that were carried over from the road-going Delta were the front grille and windscreen.
7. Lancia stated that power was around 450 hp, but many believed it was closer to 550 hp.
8. It would be succeeded by the ECV (Experimental Composite Vehicle). Lancia was already working on a successor for the Delta S4 in 1986. It was known as the ECV and it featured improved handling, aerodynamics and more power at 600 hp.
9. Lancia didn’t design the Delta S4, Abarth did. Abarth had already produced Lancia’s previous rally car, the 037, and the company enlisted their help again for the Delta S4.
10. The Abarth engine was based on Formula One technology. Rather than basing the S4’s engine on existing designs, Abarth decided to go with a whole new concept that could rev to 10,000 rpm.
11. It was the first rally car to be designed in a wind tunnel. While other manufacturers had used wind tunnels to improve their car’s aerodynamics, Lancia and Abarth designed the S4’s entire bodywork from wind tunnel tests.

Conclusion

The Lancia Delta S4 is one of the most legendary cars of all time. From its incredible twin-charged engine to its striking look, the Delta S4 will go down as a motoring icon.

References 

Jay Auger. (2014). Lancia Delta S4 (Group B) – Lancia Delta S4 (Group B) | Rally Group B Shrine

Adam. Delta S4 – Delta S4 (lanciaworkshistory.com)

wrcresults.com. Season 1986 – Season 1986 rally – eWRC-results.com

Bruce Cox. (1997). Too Fast to Race – Too Fast To Race – YouTube – Too Fast to Race (Video 1997) – IMDb