To achieve the former glorious unbeatable king of the rally level fame the Lancia Stratos achieved 82 different international rally wins. Lancia 037 was the last rear-wheel-drive to ever win a World Rally Championship in 1983, and it wasn’t capable enough to win against four-wheel drive Audi Quattro or other rivals.
Almost all the major automotive companies were building four-wheel-drive rally cars and Lancia 037 could not compete against them.
This led to the development of the Delta S4. It was Lancia’s track weapon from 1985 season to 1986 season until Group B class was disbanded from any sort of competition completely by the European sanctioning body FIA.
Though it shares the looks of Lancia Delta, it shares nothing in terms in the terms of construction with the road going front-engine Delta.
It was an evolution of the Rally 037. It took advantage of the Group B regulations and featured a longitudinally mid-mounted all-wheel-drive platform.
All-wheel drive provides superior traction and therefore results in better handling on loose surfaces.
Lancia Delta S4 Technical Specifications
The twin-charged powertrain design
The Lancia Delta S4 Stradale was powered with a 1.8-liter inline-four engine. The engine was equipped with Weber Marelli IAW integrated electronic ignition and fuel injection.
Then, this engine was supercharged and turbocharged to reduce turbo lag at low speeds.
The maximum output of the powertrain was officially rated at 483 horsepower. However, Lancia being Lancia was rumored to deliberately downplaying the maximum engine performance to trick the competitors. According to some sources, the engine could deliver more than 500 horsepower.
In 1985, Lancia tested the engine under extreme conditions, and the engine developed an insane 1000 horsepower at 72.52 psi of boost pressure.
FIA put the Delta S4 under the 2500cc class which allowed a minimum weight of 890kg.
The combined supercharger and turbocharger were commonly known as twin charging. This was a development of the Rally 037 engine that generated 325 horsepower with a supercharger only.
The Delta S4 was the first example of twin charging technology.
The Delta S4 had a comparatively large Kuhnle, Kopp, and Kausch 27 turbo with a boost threshold of 4500rpm. The turbo technology of the time had quite marked boost thresholds, with little or no response below that level. Though many mistakenly believed that this for turbo lag. But this phenomenon was known as the boost threshold and this can negatively affect the driveability of the car.
An Abarth Volumex R18 supercharger unit was part of the twin charging system and was the twin of the turbocharging unit.
The Abarth Volumex R18 supercharger provided a low to mid-range boost and improved engine response and driveability of the S4.
Superchargers do not suffer lag as they are powered directly from the engine’s crankshaft rather than by the exhaust gases. This direct mechanical connection can lead to the supercharger releasing a significant parasitic load to the engine at higher rpm levels.
Lancia designed their twincharger system in a way that the supercharger provides an instantaneous boost in the lower rpm range, switching to the turbocharger for more efficient higher rpm level engine operations.
To keep the entire powertrain setup cooler to improve efficiency and reliability, a twin intercooler system was applied.
Lancia Delta Stradale S4 could achieve 0-60mph in 2.3 seconds on a gravel road.
Name and the reason behind the name
Peugeot’s 205 T16 was a silhouette race car and shared nothing in terms of construction with the production front-engine supermini. It was named solely for marketing reasons.
Following the same principle, Lancia also decided to name their silhouette racer after the production Delta which shared nothing with the Delta S4 Stradale in terms of construction or layout.
Lancia Delta S4 Chassis and the framework
The chassis was a tubular space frame construction following the footsteps of the Rally 037.
The space frame chassis was made out of Chromoly steel alloy tubes and aluminum allot for the crash structures. Then it was covered by epoxy and carbon fiber body panels. The rear and front body panels were easily retractable and removable, allowing easy access to mechanical components at the on-event servicing and maintenance.
Lancia Delta S4 Suspension system
The suspension system featured long travel double-wishbone suspension front and rear. The front suspension had a single larger coil-over, the rear had a separate spring and twin shock absorbers to provide more comfortable ride quality and to withstand much pressure due to the added weight in the back.
Lancia Delta S4 Bodywork and aerodynamic features
The entire bodywork was done in carbon fiber composite materials. The front and rear bodywork were fully detachable to make it easy to replace due to accidental damage. This allowed easy access during the rally racing stage as well.
The bodywork features many aerodynamic tweaking including a hood opening behind the front-mounted water radiator with Gurney flap, a front splitter, and winglets molded into the front bumper panel, a flexible front skirt, and a rear decklid wing that featured a full aero foil wind section twinned with a deflection spoiler.
The doors were constructed with the same techniques used to develop the Rally 037. A hollow shell all Kevlar construction without inner door panels or any door-related equipment such as a door handle or a window winder.
The door was opened with a small racing style loop and the windows were fixed perspex with small sliding panels to allow ventilation and passing of time cards.
All-wheel drive system
The Lancia Delta S4 Stradale has a three differential four-wheel-drive setup had a three differential four-wheel-drive system.
This all-wheel-drive system was developed in cooperation with Hewland, a British Engineering company.
This also featured a center differential which allowed for 60-75% of the torque to go to the rear wheels and 30% of the engine torque to the front wheels.
The Group S Lancia ECV was supposed to replace the Delta S4 Stradale for the 1987 season, but it was scrapped along with Group B at the last minute and Lancia used a much cost-effective production-derived Delta for the 1987 season.
To comply with Group B homologation regulations, it was necessary to build a minimum of 200 road-going versions of the Delta S4.
After the Lancia S4 Stradale was designed and tested at the Lancia workshops, production of the rally racers was done in Abarth factories, especially the bodywork.
Lancia Delta S4 Stradale
The official name was the Delta S4 Stradale but it was mostly known as the Stradale.
Lancia claims to have built and sold more than 200 cars but it is more likely that fewer than 100 were actually built.
The car came with a price tag of 100 million Lira, five times the price of the Delta HF turbo, the most expensive Delta variant of the time.
The Stradale’s chassis was of a space frame construction, which was similar to its rally going sister.
The chassis was built out of Chromoly steel tubes. Chromoly steel offers an excellent strength to weight ratio. The crash structures were made out of aluminum alloy to keep the weight down. Then the entire structure was covered by epoxy and fiberglass body panels.
In comparison, the rally car had retractable carbon fiber body panels instead of fiberglass body panels which were mounted to the structure using epoxy raisin. This was the only significant difference when it comes to building the chassis.
Just like the rally car, the 1.8-liter inline four-cylinder engine was longitudinally mid-mounted, then it was equipped with a Webner-Marelli IAW integrated electronic ignition and fuel injection. Then it was mated to an Abarth Volumex supercharger and a turbocharger. Two intercoolers were added to keep the powertrain setup under desirable temperature levels to improve efficiency and reliability.
This road-going variant of the engine produced just 247 horsepower at 6750 rpm and a maximum torque of 215 lb-ft at 4500rpm.
Just like the rally-going sister car, the road-going S4 Stradale had a three differential four-wheel-drive system. The center differential sent 30% of the engine torque to the front open differential, and 70% of the rear limited-slip differential transferring 60% to75% of the engine torque.
Lancia claimed that the Lancia Stradale S4 road-going version could reach a top speed of 225 km/h. And it was able to achieve 0-60mph in under six seconds.
It also featured an Alcantra upholstered interior, sound deadening, a suede leather steering wheel, power steering, an advanced trip computer, and air conditioning as standard.
The road-going Stradales body panels were built by Torino-based coachbuilder, Savio.
Lancia Delta S4 Stradale: Competition and it’s legacy
Lancia Stradale S4 won its first victory in its maiden event, the 1985 RAC Rally in the hands of Henri Toivonen.
It also carried Markku Alen to second place in the driver’s championship the following year.
For two weeks after the end of the 1986 racing season, Alen was the crowned champion until the FIA decided to annul the results of the San Remo Rally due to irregular technical scrutineering. Alen had won the San Remo Rally and the loss of points resulted in handing the title of the driver of the year award to Juha Kankkunen of the Peugeot racing team.
In 1986, Lancia Delta S4 won three international rally events excluding the San Remo Rally win.
The Monte Carlo Rally was won in the hands of Henri Toivonen, Rally Argentina by Massion Biasion, and the Olympus Rally by Markku Alen.
Lancia Delta S4 Stradale also won the 1986 European Rally Chamionship in the hands of Italian driver Fabrizio Tabaton. This car was run by the Italian HF GRIFONE team in ESSO Livery.
The factory-supported Jolly Club team also ran several Lancia Delta S4 cars in TOTIP livery. One of those cars was driven by Dario Cerrato, the famed Italian driver with three podium finishes in World Rally Championship races. This is also the same Dario Cerrato who won the Italian Rally Championship five times.
The S4 Stradale competed in every major rally event that year except the Safari Rally in Kenya. The reason for not using the car in Safari Rally was due to the Lancia ruling that it was not developed enough to endure the extremely demanding and grueling rally stages of the Safari Rally in Kenya.
This resulted in reusing the retired Rally 037 cars for Markku Alen, Massion Biasion, and three local drivers who were participating in this event regularly.
Lancia Delta S4 Stradale was a powerful car that provided many advantages over its competitors. But it was hard to handle and lacked some required safety features like
These issues were highlighted when Henri Toivonen and his co-driver Sergio Cresto had a fatal crash on the 1986 Tour de Corse event.
He missed a tight left-hand hairpin bend and plunged into a ravine. The car burst into flames immediately, killing both drivers.
Henri Toivonen with many rally wins and podium finishes were one of the best rally drivers of his time. As a matter of fact, even after 34 years of his death, he is still considered one of the best rally drivers ever.
This led to the immediate ban of all Group B rallying events and the cars from competing in any sports event.
No proper reason is given for the cause of the accident, but there are many mysteries surrounding the crash and events prior to that.
There are many uncanny similarities between the crash that killed Attilio Bettega a year earlier and Henri Toivonen’s crash.
Lancia was developing a new rally demon called Lancia ECV (Experimental Composite Vehicle).
This was a prototype Group S rally car developed solely for the purpose of replacing the already proven rally weapon Lancia Delta S4 Stradale for the 1988 season.
However, with the ban of all Group B rallying and Group B rally cars from participating in any sports event, Group S rallying was also banned due to the dangers it posed to the driver and the spectators.
Due to this, Lancia ECV never participated in any rally events.
Lancia decided to scrap the project and use an actual production version of Delta to develop a Group A rally car. This led to the development of Lancia Delta HF Integrale.
The ECV produced more than 600 horsepower from its 1.7 twin-turbocharged inline-four engine. This engine was named the TriFlux.
The TriFlux engine was designed in an unusual fashion.
The valves were crossed, and for each side of the cylinder, there was an intake and an exhaust valve. So, there are two turbochargers that could be fed with two separate manifolds.
A single manifold carried the intake air from the three separated air ducts. This design was called the TriFlux system.
Though the Lancia ECV was capable of delivering more than 600 horsepower, Group S rules would have electronically or mechanically limited the car’s maximum power output to 300 horsepower to limit acceleration and top speed.
Following the footsteps of its forbearers, Lancia ECV was made using composite materials extensively to reduce weight. Kevlar and carbon fiber were used to create body panels.
The chassis and the tub of the car were made out of carbon fiber.
The tubular space frame was woven using the kevlar fiber to reinforce the structural rigidity.
This car has a total weight of 930kg.
It also featured a new Martini livery replacing the Delta S4 Stradale’s older Martini livery, white body featuring blue and red stripes. This all-red livery was what Martini used on 1987 season rally cars.
After the project was scrapped in favor of the production-based rally demon, the Lancia Delta HF Integrale, the prototype car was scrapped for its mechanical components.
However, after some time the Lancia ECV prototype was restored completely using original parts. After the restoration was done, it was displayed at the Rally Legend event at San Marino from the 7th to the 9th of October, 2010.
An original TriFlux engine has been prepared with the help of the original designer, Claudio Lombardi, and Claudio Berri, one of the leading turbo engineering experts.
Lancia ECV II
Despite the cancellation of Group S rally events, Lancia improved the ECV further and the final iteration was called the ECV II.
The ECV II used the carbon fiber chassis of the ECV prototype.
The designer of the new ECV II was Carlo Gaino, the head of Synthesis Design.
It was also powered by one of the TriFlux engines which were used for testing ECV.
ECV II featured improved aerodynamics and weight distribution.
With the ban of Group B rallying following the aftermath of the crash that killed Henri Toivonen and Sergio Cresto, the production of the ECV II project was halted immediately and Lancia decided to develop a new rally car based on the production Lancia Delta.