FERRARI F1-91 (643)

   For the 1991 championship the F1-90 was only slightly revised and updated in the 642 version, following the sequence of the chassis project numbers, and subsequently renamed F1-91. After the disappointing start to the 1991 season with the 642 (following the sequence of chassis project numbers but later renamed F1-91), the Maranello team sought to remedy the situation by assigning technical director Steve Nichols and chief designer Jean-Claude Migeot the task of quickly designing a new single-seater during the ongoing season. Starting from a blank slate, they created the new Ferrari 643, the last and most extreme of the 640 series cars initiated by Barnard in 1988. Although it was a sufficiently distinct model from the 642, the new car shared the F1-91 designation, as it was also used during the 1991 season.

FERRARI F1-91 (643), Alain Prost
Catalunya-Barcelona, Spanish GP 1991

   The chassis was completely new and designed to house the fuel tanks behind the driver's back, as per new regulations, with the aim of solving the weight distribution issues that plagued the 642. The suspension system was also entirely redesigned. Despite retaining the torsion bar configuration preferred by Barnard, the setup was now softer, as requested by French driver Alain Prost, who remained Ferrari's lead driver that season, alongside young compatriot Jean Alesi. There were also notable aerodynamic differences compared to the 642. The "duckbill" nose design typical of the previous models and all 640-series cars was abandoned in favor of a shape more similar to competitors McLaren and Williams. The 643's nose featured a tapered fairing, pointed at the front and wider towards the main body, with a rounded profile, nearly flat at the cockpit center and curving downward toward the front section. The entire front end of the car was also raised higher off the ground compared to the older model, with the dual goal of preventing the front wing from scraping the ground under aerodynamic load and increasing the airflow under the car, effectively simulating a raised nose. Furthermore, instead of the usual Ferrari “rosso corsa” red, the carbon fiber of the chassis was left exposed on the sides of the nose.

FERRARI F1-91 (643), Jean Alesi
Monza, Italian GP 1991

   The sidepods were also redesigned; while they retained a pronounced taper at the rear, they were shorter, wider, and lower than those on the 642. The air intakes were significantly enlarged to allow greater airflow to the radiators, which were larger than those on the previous model. The V12 engine in the 643, slightly revised by engineer Claudio Lombardi, differed from the 037 used in the 642 by having a larger bore and a shorter piston stroke, resulting in slightly reduced displacement but marginally increased power output. Despite the efforts of Maranello’s engineers, the 643 failed to overcome the chassis, performance, and reliability issues that had affected the 642. Despite its outward differences, it still suffered from notable design shortcomings, especially in terms of aerodynamics.

FERRARI F1-91 (643), Alain Prost
Magny-Cours, GP di Francia 1991

   After a promising debut in France with a second and a fourth place, achieved on the brand-new Magny-Cours circuit, which featured a particularly flat and smooth surface that didn’t challenge the cars' suspensions, the performance gap with McLaren-Honda and Williams-Renault soon widened again. The rest of the season proved disappointing, as the 643’s design flaws became evident, particularly on bumpier circuits. The car also struggled under braking, tending to lose stability and composure. Matters were further complicated by Prost’s growing discontent; bothered by rumors that Ferrari was interested in signing Senna, he criticized the car as slow and difficult to drive, pointing to inadequate suspension and steering. He even compared driving the car to driving a truck in an interview after the Japanese Grand Prix.

FERRARI F1-91 (643), Alain Prost
Monza, Italian GP 1991

   Upon learning of this statement, Scuderia Ferrari immediately dismissed the French driver, his second career firing after being sacked by Renault in 1983. For the final race of the season in Australia, on the Adelaide circuit, Prost’s place was taken by Ferrari’s third driver and test driver, Gianni Morbidelli. In the ten races in which it competed, the 643 achieved six podium finishes, four with Prost and two with Alesi, but also suffered eight retirements, highlighting the fundamental fragility of a hastily developed car meant to replace the underperforming 642. Ferrari ended the Constructors’ Championship in third place with 55.5 points, 39.5 of which were earned with the 643, but failed to secure any victories.