Guide: All In to Topple the T16 - a Historical & Technical Appraisal of the Lancia Delta S4
Background
After a disappointing debut season in 1982, the Lancia 037 came good in 1983 by winning that year’s Driver and Manufacturer World Rally Championship titles.
The rear-wheel drive 037’s state-of-the-art Group B specification meant it just about had the edge over Audi’s four-wheel drive Quattro (the car that had cleaned up in 1982). However, when Peugeot and Audi introduced four-wheel drive Group B specials, the 037 was largely consigned to also-ran status.
1984 proved a chastening experience for Lancia; the 037 scooped just one WRC victory (the all-tarmac Tour de Corse). By contrast, Audi’s revamped Quattros took seven wins en-route to both titles while the 205 T16 (introduced mid way through the season) took three.
If Lancia wanted to win another World Championship, it was clear a new four-wheel drive Group B car was needed.
At the time, rallying had a profile to match Formula 1; the awe-inspiring Group B cars drew huge crowds and media interest was off the scale. Given Lancia was upholding Italy’s national interest, there was no question of quitting.
Instead, Lancia’s in-house competition department, Abarth, was tasked with creating the ultimate Group B rally car.
A massive development programme was given the green light with a view to having a finished car publicly unveiled at the Turin Motor Show in October 1985. This would give the Martini-backed works team an opportunity to contest a couple of late season events prior to a full campaign in 1986.
For marketing reasons, Lancia instructed Abarth to develop a Group B challenger that mimicked the series production Delta. Peugeot had started the trend by designing the T16 to resemble their new 205 GTi, sales of which got a massive boost.
Codenamed Abarth SE 038, the new car would use a mid-mounted supercharged and turbocharged engine, plus of course, four-wheel drive.
It was officially titled the Delta S4 (Supercharged 4-wheel drive).
As Abarth did not have much experience with four-wheel drive, British firms Hewland and Ferguson were brought in to collaborate on the project.
To homologate a competition version of the Delta S4, Lancia would ostensibly need to build 200 road versions. However, by this stage the FIA were becoming somewhat lax in their enforcement of the rule and Lancia are believed to have produced less than 150 Delta S4 Stradales.
Chassis
The new car, built in conjunction with Turin coachbuilder Savio, was based around a tubular chrome-moly alloy steel spaceframe reinforced with composite material. Aluminium alloy subframes were attached front and rear. At 2440mm, the wheelbase was 200mm longer than the outgoing 037.
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.
Abarth fitted hydraulically-assisted 300mm diameter ventilated disc brakes, aluminium-ally single-piston Brembo calipers and Pirelli-shod 16 x 8-inch Speedline wheels all round.
A 74-litre fuel tank was mounted up against the rear bulkhead.
Engine & Gearbox
The Delta S4’s new lightweight Abarth-designed Tipo 233 ATR 18S inline four cylinder engine was developed specially for this application.
Mid longitudinally mounted, it was twin charged to reduce lag and improve torque which would prove enormously beneficial on tight and twisty rally stages.
As suitably advanced electronics were not available at the time, the complex twin charge system relied on pneumatic actuators and release valves. 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 engine cylinder.
An all alloy DOHC lump with four valve head and dry-sump lubrication, the 233 ATR 18S engine displaced 1.75-litres so as to come in at under 2.5-litres when the FIA’s 1.4 multiplier for turbocharged motors was applied. This put the Delta S4 in the 2000-2500cc class which had a minimum weight limit of just 890kg. However, as the car lacked torsional strength, Abarth normally beefed the Delta S4 rally cars up to between 950kg (for tarmac) and 1050kg (for gravel).
Overall displacement was 1759cc thanks to a bore and stroke of 88.5mm and 71.5mm respectively.
In road configuration, the S4 came equipped with a KKK K26 turbo, an Abarth R18 Volumex supercharger and two air-to-air intercoolers. The IAW 018 multipoint fuel-injection and electronic ignition were supplied by Weber-Magnetti Marelli.
With compression set conservatively at 7.0:1, the S4 Stradale developed 250bhp at 6750rpm and 215lb-ft at 4500rpm.
As the engine was ready before the chassis, Abarth shoehorned the twin charged motor into a crudely modified 037. This Frankensteinian creation was nicknamed ‘Mazinger’ after the famous Manga comic book character. The power and torque on offer proved a four-wheel drive platform was essential.
The Delta S4 ultimately incorporated both front and rear ZF limited-slip differentials plus a central Ferguson differential with viscous coupling. Typically, 30% of the power was sent to the front and 70% to the rear.
ZF also supplied the S4’s five-speed manual gearbox.
Bodywork
Despite its thickset appearance, the Delta S4’s bodywork was refined by extensive wind tunnel tests.
Panels were formed in fibreglass. Clamshell front and rear body sections tilted forwards for access to the mechanical components.
Only the windscreen, front grille and tail lights were shared with regular Delta models. The twin headlights per side were sourced from the Fiat Ritmo.
Large side scoops behind the rear quarter windows fed fresh air to the turbo intercooler on one side and the supercharger intercooler on the other. A large adjustable spoiler was mounted on the roof ahead of which was an intake scoop for the engine and oil cooler. On the road version, the roof scoop was blanked off; additional cooling was unnecessary and the space was more effectively used to serve rearward vision.
Glass windows were used throughout.
Interior
The cockpit architecture was completely new. No less then seven gauges and a bank of warning lights were housed in the main binnacle. A boost gauge was located between the 260kmh speedo and 9000rpm tach. Underneath were smaller instruments for fuel, water temperature, oil temperature and oil pressure. A clock and ammeter were positioned at the top of the centre console above a variety of switches and the trip computer.
Air-conditioning, electric windows and power-assisted steering were standard.
Suede alcantara was used for the knee roll, door centres, headliner and handsome fixed-back seats that were unique to the S4. The three-spoke Abarth steering wheel also came with a suede rim.
Although most Delta S4s were painted red, there were also white, silver, black and dark green examples.
Tan upholstery was occasionally substituted for red.
Weight / Performance
Lancia quoted a weight of 1197kg, a top speed of 140mph and 0-62mph time of six seconds.
At 100m Lire, the S4 cost five times more than a flagship Delta HF Turbo.
Competition History
Homologation was approved on November 1st 1985.
The S4 Evolution made its WRC debut on the RAC Rally later that month where Henri Toivonen and Markku Alen took a dominant one-two finish.
Despite the S4’s prodigious speed, Lancia lost out to Peugeot in 1986 after pre-season favourite Toivonen and his navigator, Sergio Cresto, perished in a fiery crash on the Tour de Corse.
After one too many accidents, Group B cars were banned from the WRC at the end of 1986.
Text copyright: Supercar Nostalgia
Photo copyright: Lancia - https://www.lancia.com
