Guide: Peak Group B - a Historical & Technical Appraisal of the Lancia Delta S4 Evoluzione (Abarth SE 038)
BACKGROUND
Between 1974 and 1976, the Lancia Stratos established itself as among the most successful rally cars of all time winning three Manufacturers’ titles for the Turin-based firm. However, ahead of the 1977 season, parent company Fiat decided to rationalise their motor sport activities.
For several years, Fiat and Lancia had gone head-to-head with one another on the special stages. That came to an end when Fiat decided that Abarth (whom Fiat had purchased in 1971) would go rallying with the more marketable 131 from 1977. Meanwhile, Lancia (purchased by Fiat in 1969) would become the Fiat group’s representative in sports car racing and Ferrari (also acquired in 1969) would compete in Formula 1.
For the remainder of the Group 4 era, the Fiat Abarth 131 eclipsed the competition to claim a trio of back-to-back Driver and Manufcaturer world titles. However, for the Group B era set to kick off in 1982, Fiat decided the more exotic machinery likely to be spawned by these relaxed regulations would better serve their more upmarket Lancia brand.
Because Group B only required a production run of 200 road cars (half that of the previous Group 4 era), manufacturers were able to create the most extreme special stage models ever seen.
The resultant Martini-backed and Abarth-designed 037 conceived for the 1982 season was in many respect a modern day Stratos - both had a state-of-the-art specification with a mid-engined layout and were designed purely to win rallies.
Like the Stratos, the 037 was rear-wheel drive as Lancia considered four-wheel drive too complex and too heavy.
Ultimately, this proved the new car’s undoing.
While Lancia did manage to wrestle the 1983 world Manufacturers’ title from Audi (whose much less exotic but four-wheel drive Quattro had won in 1982), the 037 was the last rear-drive machine to do so and never delivered a World Drivers’ Championship crown.
In the years that followed, the 037 was comfortably eclipsed by a new breed of Group B cars designed purely for rallying and with four-wheel drive. While the 037 was frequently able to compete at the sharp end on tarmac events, over the course of an entire WRC season it stood little chance against the likes of Peugeot’s 205 T16.
Even before the T16’s arrival at the Tour de Corse in May 1984, Fiat had sanctioned a replacement for the 037. Like the Peugeot (which had done wonders for 205 sales), the second generation Group B challenger from Turin would resemble one of Lancia’s production models: the Delta.
Under the skin though, the new Delta S4 would push the Group B regulations to their limit.
What emerged was perhaps the most formidable special stage car ever built.
The first S4 prototype was up and running in June 1984; Lancia began work on the competition version first and subsequently reverse engineered a production car from that. However, technical issues (particularly with the S4’s four-wheel drive system) caused significant delays.
A prototype of the S4 Evoluzione was eventually unveiled during a Turin press conference in December 1984 at which point Lancia announced they hoped to make their World Rally Championship debut with the new car on the 1000 Lakes event in August 1985.
CHASSIS
As per the S4 Stradale, the Evoluzione version was based around a tubular spaceframe fashioned from chrome-moly alloy steel. For additional reinforcement, carbonfibre was added to the Evoluzione’s longitudinal and diagonal chassis sections.
Aluminium alloy subframes were attached at either end.
A 200mm longer wheelbase than the outgoing 037 was expected to provide greater stability and more predictable handling characteristics.
Reinforced and fully adjustable suspension comprised long-travel double wishbones with coil springs and hydraulic shocks (two per side at the rear). Anti-roll bars were installed at either end.
Vented 300mm diameter brake discs were retained. However, for the Evolzione the original single-piston aluminium-alloy calipers from Brembo were uprated to four-piston items (two per side at the rear) and brake bias became adjustable from within the cockpit. An uprated hydraulic handbrake was also added.
16-inch diameter Speedline wheels were shod with Pirelli P7 tyres. They measured 8-inches wide up front and 10-inches wide at the back.
ZF supplied a new Evoluzione-specific power steering system.
Depending on the nature of any given event, a fuel tank of between 70 and 110-litres was installed up against the rear bulkhead.
ENGINE / TRANSMISSION
In the engine bay was a comprehensively enhanced version of the same Abarth-designed Tipo 233 ATR 18S inline four cylinder motor used by the S4 Stradale.
Designed specifically for this application, the mid longitudinally mounted all-alloy engine featured a DOHC 16-valve head, dry-sump lubrication and famously incorporated an elaborate twin charge system with both a supercharger and turbocharger. Conceived to reduce lag and boost torque, compressed air from the supercharger was sent to spool up the turbo which, combined with additional gases from the exhaust manifold, was further compressed by the vanes of the turbocharger. The combined forced induction was then sent through the inlet manifold and into each respective cylinder.
So as to come in at under 2.5-litres when the FIA’s 1.4 multiplier for turbocharged motors was applied (and put the Delta S4 in the 2000-2500cc class which had a minimum weight limit of just 890kg), Lancia opted for a displacement of 1759cc achieved thanks to a bore and stroke of 88.5mm and 71.5mm respectively.
In Evoluzione trim, Abarth uprated the pistons, connecting rods, crankshaft, flywheel, intake and exhaust manifolds and the dry-sump lubrication system (which now incorporated an additional radiator fed through a roof-mounted duct).
The original Weber Marelli IAW 018 multipoint fuel injection system was switched to an IAW 060 unit with four instead of eight injectors plus different fuel lines and pressure regulators.
Likewise, the Stradale’s KKK K26 turbo made way for a bigger K27 unit and the larger Abarth supercharger now had three instead of two exit ports.
Uprated air-to-air Behr intercoolers were added for both the turbocharger and supercharger, each of which got its own custom-sized exhaust.
As a consequence of these myriad improvements, only a slight hike in the compression ratio was deemed necessary (from 7.01: to 7.1:1).
To begin, Lancia quoted a peak output of 450bhp at 8000rpm and 289lb-ft at 5000rpm. However, this was soon increased to 480bhp at 8400rpm and 362lb-ft at 5000rpm thanks to a couple of tweaks to the turbo.
By the end of 1986, in excess of 520bhp was available.
Instead of the standard ZF gearbox, the Evoluzione came with a reinforced straight-cut five-speed unit from Hewland which was housed in a light weight magnesium casing and hooked up to an AP Racing twin ceramic-plate clutch.
Transmission was through a central Ferguson differential with viscous coupling and a self-locking limited-slip differential for each axle (ZF with titanium axle shafts at the front and Hewland with reinforced steel axle shafts at the rear). Later on, ZF items were used throughout.
Torque split was fully adjustable. Lancia normally opted for a 30:70 bias on gravel and 25:75 on tarmac.
BODYWORK
Externally, the S4 Evoluzione was clad with body panels fashioned entirely from carbonfibre Kevlar composite.
Compared to the prototype unveiled in December 1984 (and upon which the S4 Stradale was based), the Evoluzione homologated on November 1st 1985 featured some key changes.
At the front, instead of separate hood and bumper assemblies, a new, more aerodynamically efficient single-piece body section was designed that featured shrouded headlights, a massive integrated chin spoiler, revised intakes, bigger ventilation outlets and subtle fender flares.
It was a similar story at the back where the rear bumper was junked, simplified light clusters replaced the original Delta items, more discrete fender flares were added and the C-pillar-mounted intakes were made substantially larger.
The roof (which retained the original full width intake) was modified to incorporate a pair of cockpit cooling ducts and a huge adjustable rear spoiler.
Both the front and rear body sections were fully detachable.
All glass bar the windscreen was replaced with lightweight Plexiglas.
INTERIOR
Inside, the S4 Evoluzione bore little resemblance to the standard S4 Stradale.
The road car’s elegant dash was replaced with a boxy un-trimmed satin black affair that housed all the equipment required for top flight rallying.
Behind the two-spoke Momo Abarth steering wheel was a 10,000rpm rev counter around which an array of smaller gauges and illuminated warning buttons normally resided. Also housed on the dash were various cut-out switches, an exposed fuseboard, a trip meter and the radio equipment.
Aside from Sparco bucket seats (in the case of works cars trimmed in Martini colours with the driver and navigator names embroidered into the headrests), there was no upholstery to speak of. Instead, the austere cockpit was simply a mix of exposed composite weave, bare metal and heat insulating material. However, as a consequence of its longer wheelbase and more upright design, the S4 did offer a slightly roomier cockpit than the outgoing 037.
WEIGHT / PERFORMANCE
The S4 Evoluzione typically weighed in at between 950kg and 1050kg depending on the nature of any given event although this did rise to a little over 1060kg when the revised fire systems were brought in after the fatal accident of Henri Toivonen and Sergio Cresto on the 1986 Tour de Corse.
For smooth tarmac rallies these cars generally ran towards the lighter end of the scale while at rougher gravel events additional underbody protection was normally installed.
Depending on gear ratios, a 0-62mph time of less than three seconds could be achieved. With the longest gear ratios installed, a top speed in the region of 160mph would likely have been possible.
PRODUCTION CHANGES
After the Delta S4 was homologated on November 1st 1985, Lancia made a series of performance and safety updates in the months that followed.
From January 1986 a turbo with revised exhaust gas outlets was homologated along with a revised final drive transfer case, carbonfibre front driveshafts, centre lock wheels, uprated cross-drilled and vented discs and further reinforced rear shocks with a limited rebound system.
In April 1986 a series of titanium instead of carbonfibre chassis reinforcements were approved.
July 1986 saw the addition of further reinforced suspension wishbones and driveshafts plus an uprated brake cooling system.
The brake discs were uprated again in October 1986.
In addition to these homologated changes, items like the suspension pick-up points, springs, dampers, wheels and tyres were routinely updated, often from one major event to the next.
COMPETITION HISTORY
Following outings at a couple of comparatively minor events, ether as a course car of with special dispensation to run in an experimental class, the S4 Evoluzione made its formal competition debut on the expected day of its homologation at the Rali Lois Algarve, an all-gravel round of the European Rally Championship held from October 31st to November 2nd. Unfortunately, the solitary S4 of Markku Alen retired on the final leg with a broken propshaft.
A two-car team then contested round twelve of the World Rally Championship: the RAC Rally (November 24h to 28th). Despite a couple of technical challenges, Henri Toivonen / Sergio Cresto and Markku Alen / Ilkka Kivimaki secured a promising one-two finish to give Lancia a big boost heading into 1986.
Things got off to a good start in 1986 when Toivonen and Cresto took victory at the season-opening Monte Carlo Rally, but the Lancias did not win again until round eight, the Rally Argentina in August, by which time Toivonen and Cresto had lost their lives in a fiery accident at the Tour de Corse.
Following Peugeot’s scandalous exclusion from the Rallye Sanremo in October, the Lancia’s finished first, second and third led by Alen / Kivimaki, but this result was subsequently annulled at the end of the season following a protest from the French manufacturer.
As a consequence, despite victory for Alen / Kivimaki at the season-ending Olympus Rally, Juha Kankkunen was able to claim the Drivers’ championship while his Peugeot team had already done enough to win the Manufacturers’ title.
With Group B cars banned from major FIA-sanctioned events after 1986, works participation with the Delta S4 came to an end.
Text copyright: Supercar Nostalgia
Photo copyright: Lancia - https://www.lancia.com
