En 1976 Fiat décida de produire un produit capable de faire des rallyes sur la base de la Fiat 131 Mirafiori, qui en ce temps-là était son deuxième véhicule le mieux vendu sur le marché international.
Le but était un grand succès commercial de la Fiat 131 en cas de réussite sportive.
Le moteur choisi fut le 2-litres twin cam 131 Sport 2000 TC model. La Fiat 131 avait un châssis suffisamment rigide pour donner une solide plate-forme pour les Groupe 1 et Groupe 4. Le résultat fut la Fiat Abarth 131 Rally.
La voiture de production avait une vitesse maximale de 195 km/h, produisant 140 ch à 6400 t/m et atteignant les 100 km/h en 8,2 secondes.
Les voitures préparées avec injection développaient 215ch à 7000 t/m.
La Fiat 131 Abarth apporta le succès que Fiat espéra. Elle gagna trois championnats du monde (1977, 1978, 1980). Ses conducteurs remportèrent le championnats des conducteurs en 1978 et en 1980.
MAIS CELA EST UN PEU BREF....
Les anglophiles méritent quelques détails supplémentaires
Introducing the 131 Abarth
To begin with the 131 did not look a very likely candidate as a World beater. When launched the road version didn't even have a Twin Cam engine option. And yet the 131 was to become the dominant rally car at the end of the seventies. It all started with a debate within Fiat..........
Out of the confusions of the mid seventies oil crisis, came two strands of thinking at Fiat. They still had a newly formed rally team and a recently acquired world class Abarth organisation. While in the real world potential car buyers were still reeling from the economic impacts and high petrol prices as aftershocks of the Middle East War.
The conservative strand of Fiat thinking can be seen in the 131 Mirafiori range (announced in September ’74 as a direct replacement for the 124 saloon). The 124 Sport Twin Cam engines had gone. The 131 was a traditional saloon with a 1297cc (65bhp) or 1585cc (75bhp) push rod engine and a four speed box........
On the other side stood Abarth with a competition budget and Fiat backing to further exploit the growth in motorsport - rallying in particular. Some of Fiat's marketing managers could see the impact of the Lancia Stratos, and wanted to use Abarth to provide Fiat with similar world attention. So the history of rallying Fiats, and Abarth, and Lancia with its Bertone designed Stratos war machine become very intermixed.
Its really only in the final chapters that the 131 appears. To begin with Abarth's brief was to find a replacement rally car to the 124 Abarth - and it had to be as quick as a Stratos!
Several prototypes were developed – including the Prototipo X1/9, and 128 as well as the 131. For some time, it looked as though the Prototipo X1/9 would be the next car to carry the fight to world rallying. But in the end the 131 was chosen.
The 131 is an even more glorious choice given the capability of the Stratos to trounce most of the rally competition of the time. By 1976 the Stratos had completed its third consecutive WRC championship win. Here’s a purpose built, only just a 2 seater, wedge shaped, V6 Ferrari mid-engined monster. And its replacement is…. a 131. The contrast in looks could hardly be greater. Anyway Fiat were about to go ‘toe to toe’ with Ford for the rally crown and, in Europe at least, we were trying to forget about the oil crisis and get back to burning some more hydrocarbons in pursuit of power… we needed some serious ‘wheels’ to do it! So Fiat wanted a car that the average buyer might identify with. In this sense having a purpose built dream car in the Stratos, and a ‘street’ credible 131 together makes a lot of sense. Enter Abarth.
131 Abarth History
Many of the lessons learned by Abarth during the previous years of 124 Abarth Rally development were applied to the 131. In particular the rear suspension design is very similar, and the unreliable race inspired 16valve head from 1972 had evolved into a very reliable addition to the 1995cc engine, complete with Kugelfischer mechanical fuel injection.
Abarth had been using the 131 (and a little later the Ritmo 1500s) as development test beds for their various programmes. There are a range of 131 prototypes all usually bracketed under the 131 Abarth 035 in the books about this period… but actually a lot more prototypes were involved – including rally versions that had a few domestic rally outings. So we start with another Lancia - the Beta Montecarlo, only in 1972 it had not been decided which engine this should have. And Abarth took Fiat's V6 as the basis for testing. From late in 1973 Abarth had the first prototypes bodies of the 131 available. The 131 is a natural choice for motorsport testing - it has a big engine bay, rear wheel drive and enough room within each of its compartments to work easily, without being too wide or heavy. It was the last rear wheel drive saloon that Fiat produced in Italy.
For the next two and a half years 131s featured in Abarth's testing, in fact throughout the development of the X1/9 Prototipos. These were the first intended rally car replacement for the 124 Abarths. Only in 1975 does the 131 become the rally weapon of choice within Fiat. Bertone was tasked with assembling the 400 required to qualify (homologate) the 131 into the rally championship. 40 of these were taken in batches for Works preparation by Abarth. Later in the programme a further ten were used. The intention was to have the 131 ready for the first rally of the 1976 season.
Its final season was in 1981. Just before the arrival of the Lancia 037 Abarth in 1982.
131 Abarth Prototypes
The Abarth 030 was based on the Pininfarina X1/20 (later Lancia Beta Montecarlo/ Scorpion) and fitted with a modified version of the Fiat 130 Coupe V6 engine. It was at the moment when it looked as though Fiat might continue with their V6, and the Montecarlo might well have had one installed in the production cars. But the oil crisis of 1973 quashed that plan. In the 030, the V6 was bored out to give 3.5 litres, and was used as a development test bed by Abarth for the next two years.
In 1974 Abarth had completed the first X1/9 prototypes using a bored out and 'stroked' engine to give an 1839cc Prototipo X1/9. Initially fitted with an 8 valve head, Abarth had plans to test a 16 valve head as soon as possible. Problems, however, in extracting reliable low rev - high torque output from the heads meant chamber/ valve re-design caused delays. But a satisfactory solution was achieved a year later.
Their target was an international rally performance level to beat the Lancia Stratos. For a more detailed explanation of the X1/9 Prototipo see
http://www.sfconline.org.uk/models/x1-9 ... totipo.asp . Fiat's decision to use the commercially more acceptable 131 as a basis for their next rally weapon then meant the 16 valve head research was applied to the 131 Abarth's 2 litre twin cam instead.
The 131 SE031 Abarth here (below) in action during the 1975 Giro d’Italia (Tour of Italy) had a V6 engine derived from the Fiat 130 Coupe. The Giro d’Italia was a magnificent event open to race rally and fast road cars alike – using race circuits and stages all around Italy. In 1975 this 031 won the saloon category of the event with Giorgio Pianta the Abarth test driver at the wheel (later also manager of the Abarth and then Lancia World Rally team efforts).
The 131 body was a good choice for development, with a wide enough engine bay and rear wheel drive. The car's massive tyres were very necessary! Earlier in the 1975 season Pianta had tested the car commenting on the car's lack of stability at high speed. The Fiat V6, derived from their exploits with Ferrari and the Dinos, was designed as a cruiser rather than a motorsport engine and although providing plenty of mid-range torque has been commented on by other drivers as lacking a top end. In the 031 the engine was fitted with triple IDF Webers.
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The combination of Mr. Pianta, 031 and Fiat's resources ensured a comfortable saloon class win - despite several reported suspension, oil and fuel consumption, and gearbox problems
The SE031 was built as Fiat stepped up their budgets for the rally teams in 1974-75. Its engine was based around the type 130 B.000 in the Fiat 130 Coupe (produced between 1971 and 1977). In standard trim this was a V6 (60 degree) with bore and stroke of 102 x 66mm and 3235cc capacity, generating 165bhp DIN at 5,600rpm. Its fuel consumption was just over 19mpg. Which just about left it doomed following the oil crisis of 1973/4.
For the SE031 the blocks were bored out to give 3.5 litres with a special triple IDF Weber inlet manifold, and racing exhaust manifold (as seen in the picture) with a short 3 into 1 exhaust on either side. This engine generated 270bhp at 6800rpm.
....With its rasping V6 exhausts, it was a very noisy car!
The next 131 prototype - the 131 035 Abarth was fitted with an early Volumex supercharger based on a 16valve 1995cc Twin Cam. The capacity of the engine was also varied according to the regulations for its intended class. In the first instance the car was tested with a 1995cc capacity engine, but to keep within the 'under 2 litre' motorsport categories, forced induction engines carried a capacity penalty - so the capacity most often quoted for the 035 is 1452cc. This car also sported streamlined lightweight panels, and the car produced 290bhp with a top speed of 175mph. Made in 1979, it was entered for practice in the 1980 Le Mans 24 Hours race – driven by Pianta, but was not entered for the race itself. This was not as odd as may first appear, as it was relatively easy for Abarth to take the car, amongst the Lancia transporters and the Beta Montecarlos entered for the event for additional testing with the team already on hand.
The 035 also stands astride two eras in Abarth history. It was clear to the designers that the next generation of world rally winners would need a 50% power increase from the same capacity engines - as it looked very likely that the performance loop-hole of using the old Group 4 rally/sports prototype category would continue in some form. This inevitably would mean using forced induction.
Within the Fiat Group there was a debate about the means to achieve this. But as so often within the Group there was a political as well as engineering dimension to all of it.
Following the Stratos years, Lancia had been excluded from competing in the world rally series while the Fiat 131 Abarth was 'in play'. Instead Lancia chose to build its brand by entering the Sports and Endurance world race series. In going head to head with the likes of Porsche, some of these Lancia sports-racers used naturally aspirated engines, while some successfully adopted smaller capacity engines with turbochargers. Furthermore, in 1981, Lancia's motorsport team found a sponsor in Martini who's distinctive livery and commitment was to last over a decade.
So the debate over performance and reliability for the next world rally winner was between Abarth and their Volumex supercharger design, and Lancia with a form of the KKK type turbocharger familiar to their race team. Some technical doubts over the durability of the turbo and engine management coupled with a bigger Works design of Volumex supercharger meant Abarth won the design debate. However it was to be installed in the Lancia 037 in 1981/2 - also the Abarth SE037. For more detailed discussions of the 037 see the Lancia 037 Model page. Abarth pulled together all their experience from the X1/9 prototipos, with a similar mid engined rally car design, to ensure the 037 was readied in record time. The two cars, the Fiat 131 035 Abarth, and the Lancia 037 Abarth represent the link between the normally aspirated Fiat twin cam and the Group B Lancia turbocharged 4 wheel drive eras. It was also the last two wheel drive World Rally Champion rally car.
035 ABARTH VOLUMETRICO COMPETIZIONE
Engine Twin cam belt driven
4 cylinder in line, 1452cc*, 7,8:1 compression
82mm bore x 67,5mm* stroke [*capacity was varied during its life]
16 valve dohc head 8 valves per cam
Output 290bhp DIN @ 6400rpm
Fuel Injection with Volumex charge compressor
Lubrication: rotary pump dry sump cap. 5.1kg radiator cooled
Coolant: pump, thermostat & electric booster fan cap 7.5li
Ignition Coil and distributor electronic trigger
Fuel Tank capacity 13 gals
Gear box: 5 speed top speed 174mph
Suspension Front: McPherson strut type, coil springs, with lower wishbones, longitudinal tie rods
Rear: independent wishbones with trans
Brakes Front: disc,
Rear: disc,
Steering Rack and Pinion
Wheels/tyres Front:16ins 255(10-50)/50 Rear: 16ins 295(13-60)/50 Pirelli on special Abarth spilt rims
Body
Length 4268mm
Width 1900mm
Height 1350mm
Wheelbase 2490mm
Track Front:1500mm Rear:1560mm
Weight 1020kg unladen
131 Abarth - the Cars
So when the call came from Fiat to prepare the 131 for World Rally winning, Abarth already knew a lot about the chassis, the car and its components. They were well down the road to achieve an outright winner. The body work for the 131 Abarth was designed by Bertone, using similar weight saving techniques they had practiced with Abarth on the X1/9 Prototipo. Thin GRP-fibre glass panels were used extensively, with perspex side and rear windows. The roll cage was kept to a minimal design, commensurate with its stiffening task. And these first attempts to reduce the car's weight achieved a tarmac event weight of 973kg. This is over 65kg lighter than the standard 131 Sport, but with the extra guards and heavier duty suspension mounts/equipment on gravel rallies, this weight goes up to 1028kg.
A comparison with the Stratos power to weight figures is revealing, showing that in this important area, the 131 was in fact inferior to its 1973 sister car.
In the early cars, the spring rates were in fact the same for both tarmac and gravel versions, it was the length of travel that differed according to the event. 7inch wide wheels were used on gravel rallies, except for the 6inch used on ice, and a variety of sizes used on the tarmac rallies, exploiting the split rim design to provide a range of widths up to 12 inches. Typically, for tarmac stages, the Works cars would run 10inch fronts and 11inch rears, depending upon the driver's preferences.
The brakes were based around 12inch front and 10inch rear rotors, with twin rear calipers - the car having an additional hydraulic handbrake set. The gear box was a crash design (reduces the power loss in this era) with two sets of ratios homologated. Both were close ratio specs. There were also eight final drive options available, ranging between 6.6:1 and 3.9:1, also ZF supplied a limited slip differential.
The Kugelfischer mechanically injected 1995cc engine produced between 205bhp and 210bhp at about 8000rpm - depending on the exhaust manifold and cams chosen. With a compression ratio of 8:1 Abarth recommended a rev limit of 8500rpm!
Homologation into Group 4 of the Rally Championship required 400 road versions of the 131 Rally to be made. Lightweight body panels had been designed by Bertone who were given the assembly task too. In rally form the shell was some 50kg to 75kg lighter than standard – depending on the spec. for the particular rally. Abarth used the stiffer 2 door saloon. And in March 1976, all the preparations were complete.
The homologation (or Stradale) road version had the following general specification:
131 ABARTH Spec (homologation road spec)
Engine 138 AR1.000 Twin cam belt driven
4 cylinder in line, 1995cc, 10:1 compression
84mm bore x 90mm stroke
16 valve dohc head 8 valves per cam
Output 140bhp DIN @ 6400rpm 18 mkg @3800
Lubrication: rotary pump sump cap. 4.1kg radiator cooled
Coolant: pump, thermostat & electric booster fan cap 7.5li
Carburation Weber 34 DMTR 51/250
Ignition Coil and distributor electronic trigger
Fuel Tank capacity 11 gals, d.c. pump
Gearbox 5 speed Colotti cogs Fiat assembly, clutch: single dry plate
Final Drive Cylindrical screw, 14/50 ratio
Suspension Front: McPherson strut type, coil springs, with lower wishbones, longitudinal tie rods
Rear: independent wishbones with transverse leaf spring & telescopic shock absorbers
Brakes Front: disc, single piston & swing arm caliper
Rear: drum
Steering Rack and Pinion
Weight 980kg unladen
Wheels/tyres 14ins 185/60 HR Pirelli
Cromadora 7J
So the road going version of the 131 Abarth included a 1995cc twin cam, with a 16valve head, but with only one twin choke Weber carb. This generated about 140bhp @ 6400 rpm with a maximum of 130 lb/ft of torque at 3800 rpm. A 5 speed box was used, and Abarth homologated * rear axle ratios between 7/43 and 11/40 for competition.
Power output from the Works Rally 131 was 215bhp @ 7000 rpm, with 166lb/ft of torque at 3800. As mentioned the Works cars also had a fully independent rear suspension, Kugelfischer mechanical injection, and a 5 speed ZF gearbox. This car won 3 of the next 4 World Championships in 1977, 78 and 1980.
131 Abarth Rally Spec (basic competition spec in 1977 season)
Engine 138 AR 000 Twin cam belt driven, Abarth type 236b
4 cylinder in line, 1995cc, 10.7:1 compression
84mm bore x 90mm stroke
16 valve dohc head, 8 valves per cam
Output 215bhp DIN @ 7000rpm 23 mkg @5600, max revs 8600
Lubrication: rotary pump sump cap. 6.6kg radiator cooled
Coolant: pump, thermostat & electric booster fan cap 7.5li
Carburation KugelFischer injection (mechanical trigger)
Ignition Electronic
Fuel Tank capacity 60 litres 13.2 gals, ext. safety cell, D.C. pump
Gearbox 5 speed ZF dog, clutch: single dry plate
Final Drive Hypoid, 8 ratios ranging from about 7/43 to 11/40
Suspension Front: McPherson strut type, independent wishbones, torque reaction bars coil springs, with lower wishbones, longitudinal tie rods
Rear: fully independent trailing & lateral arms, swinging half shafts & coil springs with telescopic shock absorbers
Brakes Front: 12ins disc, inc. ventilated, dual piston caliper
Rear: 10 ins disc with dual circuit system with balance pump front/rear
Weight 973kg tarmac configuration, 1028kg gravel unladen
Wheel/tyres 15ins with ranges of tyres inc. MS 35 185/70 15 or P7 285/35 VR 15
Cromadora 7J gravel, 10J front 11J rear tarmac
Body widths 1820mm – 1520mm front track, 1492mm rear track.
Early version engine notes
Compression ratio 10,7 to 1
Bosh - Kugelfischer mechanical fuel injection, first version had DCOE type throttle bodies and manifold.
Larger oil pan - 6,6 litres capacity
215 bhp DIN (158 kW) at 7000 rpm, 23kgDIN (225 Nm) torque at 5600rpm
Oil cooler co-located beside radiator
Flywheel options 7,3kg with 230mm clutch
Nitrited crank Mechanical clutch
Abarth 84 mm pistons (part EM 939)
Abarth valve springs (part 06,131,83)
Abarth oil filter (part 90,131,00)
Cylinder head gasket 86,5 mm (part EM 876)
Intake valve 35,5mm (part EM 937)
Exhaust valve 30mm (part EM 938)
Engine gasket set (part EM 952)
Electrical Notes (Magneti Marelli)
Battery was 12V-24Ah-150A (Part 6.FC.17)
Windscreen wiper motor (80 al m/´) (Part. 5040704.1)
Starter was 12V-1,2kW (Part 5023181.1)
Coil "Super Bobina" with resistor to 8000rpm (Part BZR.204.A)
Distributor Abarth spec. (Part S.144.PA)
Alternator, six diode 12V-1000W (Part 63303425)
Voltage regulator (electronic) (Part RTT.110.B)
Abarth spark plugs (Part 7024041)
More Notes:
Weight distribution was about 50%:50% (front to rear) with crew on board.
wheelbase 2489 mm
track, front 1461 mm
track, rear 1397 mm
length 4181 mm
width 1720 mm
height 1372 mm
ground clearance in gravel trim 216 mm
fuel capacity, "abarth" tank 59 litres
Abarth built three different body strengths for tarmac, forest/gravel strength, and rough (Safari etc).
The weights vary accordingly; Early gravel models weighted 980 kg, late gravel models 1026 kg.
The heavy re inforced ones continued to get heavier each season.
The line drawing above shows the early style car layout - with the roll hoop behind the crew, and re inforcing the rear axle points only.
131 Works Performance Levels
With the later 230 hp engine and 4,88:1 final drive
0-30 mph 2,6 seconds
0-60 mph 6,6 seconds
0-100 mph 17,5 seconds
Top Speed 115mph @ 8000 rpm
Standing 1/4mile 14.6 seconds
131 Abarth Timeline
By October 1975 Bertone had mostly completed the preparation of the 400 131 Abarth needed for FIA Homologation into the Group 4 category of the world rally championship. 50 of these cars were earmarked and duly dispatched to Abarth for Works preparation (Preparazione Corsa). The aim was to achieve a fully rally competitive car later during the 1976 season.
The Works cars were developed in three states of trim/tune to meet the demands of the world's rallies, Snow and ice, Gravel and Tarmac. Although we might argue that the Safari Rally spec became a fourth special trim state later. They were not precise about the detailed spec of some of the cars - so you can find small variances in the specs on some of the photos of the time.
The homologation changes gave Abarth some flexibility in the car specs they used, so that aluminum paneled doors, perspex side windows, additional lighting configurations with big or small spot lights can be seen. The size and finish of the can also be from another spec, and out of place to the purist. So the wide wheeled tarmac cars extended arches can be seen on other than tarmac events