Four-wheel-drive system
Lancia's first four-wheel-drive car was a Delta. As early as April 1982, a turbocharged four-wheel-drive Delta Turbo 4x4 prototype was shown at the Turin Motor Show to gauge public reaction, and tested by journalist at the La Mandria test track.[31][32] It was based on the regular production model, but had a 128 bhp 1.6-litre turbocharged engine, four disk brakes, and a top speed of over 190 km/h. Its drivetrain was however not related to the more sophisticated one found on the first mass produced four-wheel-drive Lancias, which were shown at the 1986 Turin Motor Show: the Delta HF 4WD and its tamer saloon sibling, the Prisma 4WD.
The four-wheel-drive system used on the Delta HF 4WD and all HF integrales was instead based on the one developed for the 1985 Lancia Delta S4 Group B rally car, albeit in a transverse front-engine instead of a longitudinal mid-engine layout.[32] Both systems used three differentials, the central one being an epicyclic gearing controlled by a Ferguson viscous coupling. The epicyclic gearing split torque on the two axles according to a fixed ratio, determined by the number of teeth on its gears. Initially front biased to maximize traction according to static load distribution, the torque split became increasingly rear-biased with every successive iteration of the Delta HF. The epicyclic gearing received motion via its externally teethed ring gear, which meshed with a pinion on the five-speed gearbox lay shaft. From there it was transferred to the front differential via the sun gear, and to the rear differential via the planet carrier, a couple of 90° bevel gears and a three-piece drive shaft.
The Ferguson coupling's purpose was to transfer torque between the axles. During normal operation, i.e. when the two axles rotated at the same velocity, it did nothing, simply rotating as a unit. As soon as there was a difference in velocity between the two axles, it began transferring torque from the faster to the slower rotating axle—which is usually the one with better grip. When difference in velocity became extreme, it locked up completely, nullifying the slip between the axles and transferring the maximum amount of torque. Finally there were the other two differentials: a conventional open one at the front and a Torsen (torque sensing) type one at the rear. Supplied by the American Gleason Corporation, the Torsen differential automatically divided the torque between the rear wheels according to the available grip, with a maximum lock-up of 70%.
Delta HF 4WD
The Delta HF 4WD was unveiled at the April 1986 Turin Motor Show,[33] becoming the top of the Delta range.
The HF 4WD's 1,995 cc, twin-cam, eight-valve engine with two counter-rotating balancing shafts was derived from the Lancia Thema i.e. turbo saloon. It was equipped with a Garrett turbocharger, a wastegate valve, an air-to-air intercooler and Weber IAW integrated electronic ignition and fuel injection; to support turbocharging it also adopted tri-metallic crankpin and main bearings, sodium-filled valves, bronze valve guides and an oil cooler.[34][32] Engine output was 165 PS at 5,250 rpm, and 26.5 kgm of torque at 2,750 rpm, that could rise to 29 kgm for short periods of time thanks to an overboost function.[32] On the Delta HF 4WD the torque split ratio of the central epicyclic differential stood at 56/44 front to rear.
Delta HF integrale "8V"
The Lancia Delta HF integrale incorporated some of the features of the Delta HF 4WD into a road car. The engine was an eight-valve 2.0 L fuel injected four-cylinder, with balancing shafts. The HF version featured new valves, valve seats and water pump, larger water and oil radiators, more powerful cooling fan and bigger air cleaner. A larger capacity Garrett T3 turbocharger with improved airflow and bigger intercooler, revised settings for the electronic injection-ignition control unit and a knock sensor, boost power output to 185 PS at 5,300 rpm and maximum torque of 31 kgm at 3,500 rpm.
The HF integrale had permanent four-wheel drive, a front transversely mounted engine and five-speed gearbox. An epicyclic centre differential normally splits the torque 56 per cent to the front axle, 44 per cent to the rear. A Ferguson viscous coupling balanced the torque split between front and rear axles depending on road conditions and tyre grip. The Torsen rear differential further divides the torque delivered to each rear wheel according to grip available. A shorter final drive ratio (3.111 instead of 2.944 on the HF 4WD) matched the larger 6.5x15 wheels to give 24 mph/1,000 rpm (39 km/h per 1,000 rpm) in fifth gear.
Braking and suspension were uprated to 284 mm ventilated front discs, a larger brake master cylinder and servo, as well as revised front springs, dampers, and front struts.
The HF integrale was facelifted with bulged wheel arches for the wider section 195/55 VR tyres on 15-inch 6J alloy wheels. A new bonnet incorporated air louvres while the restyled bumpers wrapped around to meet the wheel arches at front and rear. The front bumper, now wider, incorporates air intakes and for the rectangular auxiliary driving lights. The side skirts are faired into the wheel arches at front and rear and the twin rear view mirrors are finished in body colour. There were only 50 RHD factory built cars, none of which were officially imported to the UK.
Delta HF integrale 16v
The 16v integrale was developed for rallying, introduced at the 1989 Geneva Motor Show, and made a winning debut on the 1989 San Remo Rally.
It featured a raised centre of the bonnet to accommodate the new 16-valve engine, as well as wider wheels and tyres and new identity badges front and rear. The torque split was changed to 47% front and 53% rear.
The turbocharged two-litre Lancia 16v engine produced 200 PS at 5,500 rpm, for a maximum speed of 137 mph (220 km/h) and 0–100 km/h (0-62 mph) in 5.7 seconds. Changes included larger injectors, a more responsive Garrett T3 turbocharger, a more efficient intercooler, and the ability to run on unleaded fuel without modification.
Alongside the 16v Lancia introduced an eight-valve variant equipped with a three-way catalytic converter—which reduced output to 177 PS — intended for those European markets where such emission control equipment was mandatory.
In the summer of 1990 some small updates were made to all Delta sports models, with the integrale receiving new upholstery materials.[28] Like on the HF turbo, the combination of light grey Alcantara and multicolour stripe cloth used since 1986 was replaced by dark grey Alcantara with diagonal stripe velour. If the Recaro optional seats were ordered, the buyer could choose either full dark grey or green embossed Alcantara upholstery, or extra-cost perforated black leather.
Delta HF integrale "Evoluzione"
At the September 1991 Frankfurt Motor Show Lancia introduced an heavily revised Delta HF,[36] once again named "Delta HF integrale"—but which became better known as the "HF integrale Evoluzione" or simply "HF integrale Evo". Evoluzione cars were built from October 1991 through 1992. At the end of the victorious 1991 World Rally Championship season, where the HF integrale 16v had won both the drivers' and manufacturers' championships, Lancia officially retired from rallying. Despite this, racing development of the HF integrale continued, and factory-developed HF integrale Evos were fielded by independent Martini Racing-sponsored Jolly Club for the 1992 season. Thanks to the two factory-backed privateer teams, Lancia won its sixth and final consecutive Constructor's World Rally Championship. These were to be the final homologation cars; the catalytic 1993 Evoluzione 2 was not developed by the factory into a rally car.
The Evoluzione's engine was the same turbocharged 16-valve two-litre used on the previous model, but power had increased to 210 PS at 5,750 rpm, chiefly thanks to a new, single outlet 60 mm diameter exhaust system.[37] Maximum torque was unchanged at 31 kgf.m, but was now reached at a higher, 3,500 rpm.[38] An eight-valve "kat" catalytic converter-equipped variant, with an unchanged 177 PS output, continued to be produced for countries where such equipment was mandatory.
Delta HF integrale "Evoluzione II"
Presented in June 1993, the second Evolution version of the Delta HF Integrale featured an updated version of the two-litre 16-valve turbo engine with more power, as well as a three-way catalyst and Lambda probe.[40] A Marelli integrated engine control system with an 8 MHz clock frequency was installed, incorporating:
The engine developed 215 PS DIN (against 210 PS on the earlier non-catalytic version) and maximum torque of 32 kgf·m (314 N·m) (formerly 31 kgf·m or 300 N·m).
The 1993 Integrale received a cosmetic and functional facelift that included:
With ABS, fog lamps and Recaro seats now standard on all markets, the sole optional extra was air conditioning. The choice of paint finishes was reduced to just three solid colours: bianco (white), rosso Monza (red) and blu Lancia (dark blue).[41] Interior upholstery was always done in beige Alcantara with diagonal stitching on seat centres and door panels. Additional colour and trim combinations were made available through a number of limited editions.
- Timed sequential multipoint injection
- Self-adapting injection times
Limited editions and specials
Lancia produced several limited and numbered editions models based on the Delta HF Integrale "Evoluzione", each offering unique exterior and interior colours, materials and equipment. Some were put on general sale, while others were reserved to specific markets, owners clubs or selected customers. The following table lists all of the limited editions and their main features.
A notable one-off model was the Lancia Delta Spider Integrale, a two-door convertible built for Fiat president Gianni Agnelli.[55]
After production had finished in 1994, Bruno Maggiora tried to convince Lancia to continue the Delta with a third evolution which was realized in the Delta HF Integrale "Viola", the one and only "Evo 3" car named by its intense violet color. The concept features a new injection system, an IAW P8 ECU and an increase in boost for the Garrett T3 turbocharger, boosting power from 215 to 237 PS at 6,000 rpm and 236 lbft of torque. It also features a GKN limited-slip differential, a new clutch for the center differential, a short shift gearchange and revised springs and dampers.[56]
In 2018, a small Italian coachbuilder called Automobili Amos created a modern version of the Delta Integrale, named the Delta Futurista. Power was up to 330 PS and the car itself weighed 1250 kg. Additionally the rear doors were removed, making it a three-door body. Only 20 examples were produced, each costing £270,000.[57]