Alfa Romeo celebrated its 75th birthday in 1985 by presenting the heir to the 1977 “New Giulietta”: the 75. The 75 Turbo Evoluzione, specially developed for racing, arrived shortly afterwards. The IMSA version – created to take part in the 1988 Giro d’Italia and with its power further upgraded the following year – was to be the most powerful and successful.
The Alfa Romeo Design Centre, headed by Ermanno Cressoni, achieved the magical feat of transforming the looks of the modern 1977 Giulietta by placing the emphasis even more firmly on its mechanical layout: engine at the front and gearbox and transmission at the rear. Previewed at the 1986 Geneva International Motor Show in racing trim, the1.8i Turbo Evoluzioneversion was specifically created to obtain Group A type approval in the 3 litre Class. To calculate the Class of a supercharged engine, the displacement is multiplied by a preset coefficient, which in those years was 1.7.
Therefore, to make the 3000 Class the original displacement of 1779 cc – which would have given a total of 3024 – was slightly reduced to 1762 cc; this reduction in displacement was insignificant in terms of performance, which was boosted by changes to the supercharging pressure and the intake ducts. The large aerodynamic add-ons – spoilers and side skirts – reduced the penetration coefficient to provide a considerable increase in top speed. With the same power as the 75 1.8i Turbo models (155 hp), the on-road version of the Evoluzione achieved a top speed of 210 km/h.
Compared to the on-road configuration, the Alfa Romeo 75 Turbo Evoluzione prepared for Group A competition had an even lighter and stronger body, and to improve precision, rigidity and strength, the elements connecting the mechanical components to the body were replaced by metal ball joints. In the first version, the permitted modifications to the engine boosted its power to about 290 horsepower.
To take part in the 1988 Giro d’Italia, the Alfa Racing Department brought the Group A 75 into line with the International Motor Sport Association rules. This produced the most powerful 75: the Alfa Romeo 75 Turbo Evoluzione IMSA. After its debut success, Alfa also competed in the 1989 edition: two crushing victories, with the car taking the top three places in both races.
In 1988, the Turin Automobile Club organised the ninth edition of theGiro Automobilistico d’Italia. As well as Group N and Group A cars, the event was also open to vehicles tuned and power-boosted in accordance with the American IMSA Endurance Regulations, which also included Group 5 and Prototype Gran Turismo cars. In just two months the Alfa Racing Department, led by Giorgio Pianta, came up with the IMSA version of the new 75 Turbo Evoluzione, placing its fine-tuning in the hands of test driver Giorgio Francia.
The IMSA Regulations put fewer restrictions on the changes which could be made. So the car’s track was widened and large plastic mudguards were fitted, while the large carbon fibre spoiler on the boot was increased in size. Further changes to lighten the car reduced its weight to just960 kg. As is often the case with racing cars, there are no specific data on its maximum performance, which depended on the different gear ratios used for each circuit. During their racing career, the cars’ power underwent major changes, upgraded from about 335 hpin the 1988 version to 400 for the car which competed the following year.
The Giro d’Italia automobilistico was an event that combined the appeal of the racetrack with that of rallying, because it featured races on the top Italian circuits (Monza, Misano, Varano and Vallelunga) interspersed with special and transfer stages on the roads used by the biggest national and international rallies. To meet these characteristics, teams consisted of a circuit racing champion and a rally crew of driver and navigator. The Alfa Racing Department entered three cars in the 1988 edition, and they crossed the finishing line in the order Patrese/Biasion/Siviero, Larini/Cerrato/Cerri and Nannini/Loubet/Andrié. The following year Alfa again monopolised the race with an all-Italian top three: victory went to Francia/Cerrato/Cerri, ahead of Larini/Biasion/Siviero and D’Amore/Noberasco/Cianci, the third-placed team driving a Group A 75 Turbo Evoluzione, followed home by the third 75 IMSA of Guerrero/Loubet/Andrié.