The Car That Ended Group B: Lancia Delta S4

Often referred to as the ‘Golden Era of Rallying’, the Group B regulations lasted from from 1982 to 1986. The cars were terrifying turbocharged monsters that drifted their way across five continents at a frightful pace. From the frozen tarmac above Monte Carlo, between towering snowbanks in Sweden, past rabid swarms of fans in Portugal, over Kenya’s blistering heat and hostile uneven surfaces, to the back breaking jumps of Finland -- motor racing enthusiasts around the globe experienced the hair-raising speed & unfettered madness that was Group B.

The simplified design goal for this era of Rally: Build the fastest and lightest two-seat off-road machine possible at the expense of safety. Wildly popular, as evidenced by Youtube clips of the crowds lining the roads, it was recently highlighted by an episode of the Grand Tour (Season 2, Episode 7 ‘It’s a Gas, Gas, Gas’, available only through Amazon Prime) that documents the titanic struggle between the precision of Audi Sport versus the guile at Lancia during the 1983 WRC season. In that year, the Lancia 037 miraculously, and often underhandedly, won the Manufacturer’s Championship using a rear-wheel drive car (the last to do so), punching well above their weight against Audi’s four-wheel drive marvel of technology.

Knowing they had to adapt with the times against Audi’s Quattro S1 and Peugeot’s 205 T16, Lancia built the Delta S4 by the end of 1985 to fully enter into the 1986 Championship. At the heart of their new creation was a 1759cc mid-engine inline-four capable of going from 0 to 60 mph in 2.4 seconds; an Abarth Volumex R18 Supercharger (up to 4500 rpm) & a KKK K27 Turbocharger (beyond 4500 rpm) -- together they’re often called ‘twin-charging’ or ‘double-supercharging’ to eliminate the design challenge of this time period: Turbo lag. Upwards of 550 horsepower was possible from this unique setup, though some purport a figure near 1000 hp in testing at 5 bar of boost (2.2 bar in race trim). Among the first teams to use a wind tunnel and computer assistance, Lancia sought every modern advancement to keep their tubular space-frame chassis near the minimum weight of 890 kg, but for reliability they reinforced the Delta S4 to 950 kg for tarmac and 1050 kg on loose surfaces. They used light-carbon and kevlar composites for various body panels; acrylic windows; an easily separable ‘clamshell’ body for servicing; cooling via a scoop on the bonnet (radiator), the roof (oil) and two rear scoops for the intercoolers (one for the supercharger, the other for the turbocharger).

So what is it like to drive this car from a bygone age of unrestrained engineering prowess? In real life it required near superhuman talent and fearlessness from hallowed people like Alèn, Blomqvist, Mikkola, Muton, Röhrl, Salonen, and Toivonen to tame these radical machines. Lucky for me, I was able to experience the insanity of Group B whilst retaining my health via the magic of Virtual Reality. The Rally Legends software team offered me a preview of their work-in-progress Delta S4, it’s built inside of Kunos Simulazioni’s Assetto Corsa simulation.

I drove this snarling beast around the French tarmac stage of ‘Joux Plane’ (imported from Richard Burns Rally) and felt nearly overwhelmed by the blinding acceleration forcing me to rapidly change gears just to keep up! Signs, trees, bushes and posts whiz past at an alarming rate as I frequently hit 200 km/h on any short straight of road. The weight transfer is visibly severe; the car pitches up with every press of the throttle, then instantly dives forward as I desperately stamp on the brakes to stop for each bend.

This product isn’t complete yet, but I’ve thoroughly enjoyed what is available thus far. I experienced a few Issues, such as: Clipping through the character model’s helmet in VR; the hydraulic handbrake isn’t properly implemented; I’m unsure if the supercharger and turbocharger combination is working as intended (I occasionally encountered the power bogging down, not a documented characteristic in the real car). There’s already an Audi Quattro S1 E2 in Assetto Corsa, so I look forward to comparing the two together in future!

The Delta S4 found instant success during their debut at the final round of the 1985 in Rally GB. Despite their fast pace, each S4 chassis required a full rebuild after an event, high cabin temperatures from the proximity of the engine and gearbox caused major concern, and the throttle could potentially stick after repeated damage to the floorboard.

In what would be the final year for Group B, the Lancia earned additional victories in Monte Carlo, Argentina and Greece (the San Remo results were excluded because of a controversy involving the Peugeot side skirts). Henri Toivonen & his co-driver Sergio Cresto were well on their way to possibly winning the 1986 Championship. Before they had a chance to achieve such glory, they approached a tight left-hand hairpin at the Tour de Corse tarmac rally, tumbled over a stone wall, plummeted down a ravine and were stuck amongst the dry trees. The tree limbs likely pierced the thin aluminium fuel tank (located under the driver seats and only protected by skid-plates on gravel/dirt rallys) and an already hot racing car was instantly engulfed in flames. With their deaths, a total of 4 drivers/co-drivers and 3 spectators perished during these years. FISA deemed the Group B regulations as too dangerous to continue and they instituted the Group A formula for 1987.