Ultimate Group B Rally Car - Delta S4

The Group B era of Rallying was kickstarted in 1982 after a shake up of the rules by FISA ( Now the FIA) to allow more freedom for engineers in hope to increase the manufacturer presence in the World Championship. This freedom had virtually no baggage attached with the only key regulation being that the manufacturer had to build 200 road going versions before they could proceed to build 20 Rally cars (an additional 20 road cars would have to be built for evolution variants to be built. The First Group B car to burst onto the scene was the Audi Quattro, although the concept of the car dated back to 1980 and was predominantly designed for the older Group 4 regulations. The Quattro was competitive right out of the box although with a few reliability issues but the car did not have much competition in the early year of Group B. This was when Lancia returned after a four year break with the Lancia Rallye, more well known by its Abarth project code 037.


The 037 got off to a rough start with a double retirement on its first event, The Costa Smeralda and this bad luck continued for most of the year. The cars first victory came six months after its debut at the PACE Rally in Wales with Markku Alen as a practise for the RAC Rally in November of the same year. Lancia hit the ground running in 1983 with Walter Rohrl and Markku Alen starring in its driver lineup for the 1983 season. The Monte Carlo Rally was a sign of things to come with Rohrl winning and Alen finishing in second. Rohrl only did selected events that he enjoyed but that was enough for the car beat the mighty Audi Quattro to the Constructors title in 1983. As a result it was the last rear wheel drive car to win a Constructors title in the WRC. For 1984 Lancia introduced a second evolution model with power up to 325bhp, but it was not enough to be a competitive all round package despite winning the Tour De Corse Rally with Alen. The 037 had a lot of success in regional championships with Miki Biasion winning the European Rally Championship in 1983, Carlo Capone in 1984 and Dario Cerrato in 1985. 


1985 Proved to be a tough year for the Lancia squad. At the Tour De Corse Rally Attilio Bettega was killed when he lost control of his car and hit a tree head on, killing him instantly. His co driver Maurizio Perissinot escaped uninjured.The long awaited replacement, the Delta S4 could not come soon enough. The 037 remains today one of the finest Rally cars ever produced and they are still being rallied successfully today in a variety of Historic championships.



Lancia already knew in 1983 that 4WD was the way forward and as of April 1983 the work on the 038 (internal project code for the Delta S4) began. Lancia would be beaten to the punch by Peugeot, with its mid engined, 4WD 205 T16, which was announced in early 1983 but did not burst onto the scene until 1984.


In 1983 the third 037 prototype was used to create Mazinga named after a cartoon monster. Mazinga carried an early Delta S4 engine with the Turbo and Volumex producing 700bhp to the rear wheels only. This prototype was purely to gain an understanding about the engine and the chassis, with the mechanical work being left purely as a 037 prototype. This was done so they could get the twin charging concept onto the La Mandria test track so gain an understanding of how the car would work under various conditions. The main goals of this testing were to see how the car would drive and also the cooling especially of the compressed air and engine oil. The rear wing which had the function of creating a very high downforce, but also designed to push air in to the engine bay for the two intercoolers and into the vent in the roof for the radiator. This proved to be a success as the placement for the intercoolers in the C pillar and the Roof vent for the Radiator were carried onto the final Delta S4. Mazinga first moved under its own power in July of 1983. The two stage intercooler was also used on this version of the car hence the new rear clamshell to house the engine.


The Mazinga was a bit of a beast for highly skilled test driver Giorgio Pianta with the rear axle breaking traction in 5th gear and after the tests he named the car a tyre lathe. As a result of this a large rear wing was added to the car as of October 1983.



At the end of 1983 the first tubular chassis was completed at CECOMP and was delivered to the Abarth workshops in Turin for the engineers to test for torsional strength in the new year. The first car (SE038-001) was up and running for its first tests in June of 84 at La Mandria alongside a 037 for a comparison test. After many months of hard work the SE038-005 was ready for its official reveal to the public on the 13th December 1984. Markku Alen and Henri Toivonen were present to drive SE038-001 at Campo Volo with a camera crew that broadcast the footage back to the Abarth Workshops.


After the Lancia and Abarth engineers virtually started from scratch, as only some elements of the suspension design were carried over from the 037. Designed as a competition car from the ground up, the Delta S4 was built around a spaceframe chassis constructed from with all four corners being fitted with double wishbones and coil springs. At the front, the suspension sported single telescopic hydraulic shock absorbers while twins were fitted at the rear. As in the 037, the engine was installed longitudinally but it was also turned around 180 degrees to allow for the gearbox and the transfer case to be mounted centrally for a better weight distribution. The engine was rooted 20 degrees towards the left with respect to the vertical axis. However this means if the car would need to have its gearbox replaced it would take much longer than it would on a 037. Lancia worked alongside Hewland to develop the 4WD system which consisted of a Ferguson viscous coupling with an epicyclic centre differential. The power transfer could be adjusted from 25/75 front/rear to 40/60. On both the front and rear axles a ZF limited slip differential was used. The slip could be adjusted and was normally set at 25 per cent at the front and 40 per cent at the rear. The gearbox was also sourced from Hewland and this case being a dog leg 5 speed manual.


The most famous aspect of the S4 is its unique 1,759 cc Turbocharged and Supercharged engine with a maximum of 2bar of boost developing near 600bhp. This paired with a 980kg weight gave the car fast acceleration and a nimble handling. While providing excellent low end power, the supercharged 037 engine was found to be a little lacking at the high end of the rev range. To fix that issue the Lancia/Abarth engineers decided to use a Volumex supercharger from the 037 and a KKK turbo. This system worked wonders for Lancia with the bypass value opening passing 1 bar of pressure from the Volumex to the Turbo. The system also included a pop off value placed in a channel parallel with the engine designed to veer away the flow of compressed air before entering the engine by a spring system in two key situations. the first of these being when the pressures are to high inside the engine in order to save vital components from failing. The Second being the most important, during lifting off the throttle. Due to the air and fuel mixture not being ignited due to the fuel not being injected with no throttle and the air not taken in by the engine is sent to the turbo to reduce the impact of turbo lag resulting in the engine being more response especially in the lower rev range. The system may sound very complicated which it is, but it worked remarkably well and during its rallying career the S4 rarely suffered an engine related failure.


The car was introduced in 1985 with its first World Championship appearance being the 1985 RAC Rally. Lancia set out with two cars for Markku Alen (chassis 207) and Henri Toivonen (chassis 202) and immediately showed the great pace of the new car. Henri Toivonen went on to win the event with Markku Alen in second place. The success followed on from the RAC to the 1986 season with Toivonen winning the 1986 Rally Monte Carlo despite being involved in a collision between stages with a Road car which required work to be carried out at the road side by the Lancia/Abarth mechanics. After the slight drama Toivonen extended his lead even after initially struggling with the handling of the car as a result of the damage sustained.


However the luck didn’t carry on to snowy Sweden as Toivonen retired with engine issues but Alen brought the car home to second place behind Juha Kankkunen in the 205 T16. The stage was set for an epic battle between the Lancia’s, Peugeot’s and Audi’s as the teams headed to Portugal. Lancia set up camp at Estoril for a spot of testing a couple of weeks before the rally. Estoril was no stranger to rallying as it was commonly used as a test venue for World Championship teams to test their tarmac setup for the roads around Sintra and even served as a regroup area for the Rally. As was commonly done at all tests the engineers would record the times of the car through the day in order to track progress. With Henri Toivonen on hand to put the car through its paces and being able to use full boost (2.2 Bar on the S4 to produce in access of 560bhp) something that could be rarely done due to the size of the stages in a Rally. Toivonen’s time was good enough to put him in the top ten of the times set by the F1 cars at a test earlier in the year. Considering the F1 cars of that time could produce over 1000bhp in qualifying trim that’s a pretty impressive feat if you ask me. Back then the difference between a Rally car and a Formula One car was not as big as it is today. However the Rally was short lived after the RS200 of Joaquim Santos left the road on the famous Sintra stage.


Next up was the Tour De Corse and Lancia were the firm favourites going into the event but 1986 was to be a tough year for the Turin team. On Stage 18 after the service in Corte, Henri Toivonen and Sergio Cresto were tragically killed when their Lancia Delta S4 left the road on a left hand corner roughly 7km away from Corte. This marked accident brought sadness and shock to many teams, drivers and fans. Henri had won 12 out of 17 stages with stages like Petreto - Aullene 1 averaging speeds of 117.66 km/h. Lancia’s team boss, Cesare Fiorio, later claimed that he was the only driver that could really control and maximise the power of the Delta S4. Henri left behind a wife, Erja, and two young children, Arla and Markus. Sergio was single and had no children. Group B ended on a small corner in Corsica. This cemented the teams and FISA’s thoughts of ending Group B. FISA introduced the new Group A rules for 1987. However Lancia were not done here.


The Lancia team continued on with the rest of the season with young gun Miki Biasion having a permeant seat in the factory team. Between Alen and Biasion they managed to win another three events in the championship and after many tough rallies, Markku Alen was crowned Champion. What a relief after 3 years of development, countless hours the car was proved to be the best of the front runners. However it was not to be as after the Sanremo Rally, the points were dropped after the Peugeots were excluded for having illegal sideskirts. Markku Alen and Lancia lost the world championship only 12 days after they were crowned champions.


“When Markku Alen was asked what it was like going from Group B cars to Group A at the end of 1986 and beginning of 1987. I can answer that easily: it felt like the world had just ended. I had just lost the championship after 10 days so I was really depressed and then they gave me what was going to be our new car to test, at Ivalo in Finland. I was really shocked: compared to the S4, the Group A Delta felt like a road car. Our S4 was developing about 700 horsepower by the end; the Group A Delta had around 230. It just felt like driving a road car and I was so frustrated by everything I really wondered what the point was in continuing. I never liked that Delta: although we had some good results with it, this was never ‘my’ car and I rolled quite a few of them. The S4 was developed and built around me, so although it was a bit like a NASCAR – all power and noise, really not so sophisticated at all – my feeling with it was a lot better.”


Even today Markku Alen classes the S4 as his favourite rally car and with good reason as it brought him so close to a World Championship. Lancia went on to dominate the Group A era ranking in 6 manufacturer titles with the Delta HF4WD and Integrale. Today the S4 is loved by many fans and its a real credit that the majority of the owners still use the cars as they were intended. Its a big shame that the life of a heavily anticipated project was cut short along with the lives of who I consider the greatest rally driver in history. The Delta S4 remains one of the greatest cars ever to be seen on the World Rally Championship, built by the most successful Rally team and driven by the best drivers of their time.


Special Thanks to Sitorally.com for allowing the use of their fantastic photos of Chassis 217 for this article.
Information from Lancia Delta S4 Book, and Lanciaworkshistory.com.