Alfa Romeo had returned tosports car racing in 1967 with the purpose-built Tipo 33. Powered by a two-litre V8 engine, the Autodelta developed machine had originally been intended to fight for class victories. A rule change that came into effect at the start of 1968 brought outright victories within the grasps of the prototype racers. The displacement limit for these machines was set at three litres, so some work was required for the Tipo 33 make the most of these rule changes and Alfa Romeo continued with the two-litre version in 1968.

Autodelta's Carlo Chiti had anticipated the need for displacement increases in the future and had left enough 'meat on the bone' of the all-aluminium to make this possible. One of the reasons for this was that Formula 1 also had a three-litre displacement limit. Both the bore and stroke were increased for a new swept volume of 2,998 cc. The heads were also upgraded and featured four valves per cylinder for the first time. Equipped with a Lucas-sourced fuel injection system, the enlarged V8 produced around 400 bhp in its original guise.

The existing space frame chassis was not quite up to the task of coping with the increased power of the larger engine. Instead a brand new, full length aluminium monocoque was constructed. Suspension was by double wishbones at the front and reversed lower wishbones and top links with trailing arms at the rear. The engine was mated an Alfa Romeo gearbox, which had five forward gears. While the two-litre Tipo 33 was usually raced with a coupe body, the new-for-1969 Alfa Romeo racer was developed and tested with an open 'Spider' body.

Although effectively a brand new car, the three-litre Alfa Romeo sports racer was again referred to as a Tipo 33. It was ready for testing early in 1969 and Alfa Romeo announced a very ambitious program, signing John Surtees among others as one of the drivers. Three examples were entered in the Sebring 12 Hours but struggled both with pace and reliability. A single car was tested at Le Mans but none were raced due to reliability concerns. After Le Mans, the T33/3 returned to the track, one fitted with a striking coupe body. Nino Vaccarella qualified it on pole at Hockenheim and drove it to victory at Enna.

 

Over the winter subtle improvements were made to the T33/3 focusing on sorting the reliability issues and shedding weight. Progress was certainly made as a victory was scored in Buenos Aires and a T33/3 placed third at Sebring. Unfortunately, the five-litre Porsche 917 and Ferrari 512 'GT' racers also came to the fore, relegating the three-litre prototypes back to chasing class wins. These were scored at Imola and Zeltweg and one of the three T33/3s entered in the 24 Hours of Le Mans ran as high as second before retiring with an alternator failure after 18 hours.

Realising that the three-litre cars would be no match for the bigger 917s and 512s on high speed tracks, Autodelta redeveloped the T33/3 to better suit events like the Targa Florio. Smaller, 13" wheels were fitted and the nose was redesigned to accommodate for the revised wheels. The changes really paid off as the 1971 specification T33/3 placed second at Sebring and first in class. Andrea de Adamich and Henri Pescarolo won the Brands Hatch 1000 km outright. Class wins were also scored at Monza, Spa and Zeltweg, while T33/3 won the Targa Florio and Watkins Glen 6 Hours outright.

With the 917 and 512 banned from 1972, new opportunities emerged for the T33. The car was redeveloped into the T33/TT/3, which boasted a new space frame chassis and a transverse gearbox. Faced with strong competition from Ferrari and Matra, it did not prove nearly as successful as the T33/3 had been in 1971. Some of the surviving cars were sold to privateers, who continued to race the T33/3s in a wide variety of events, including even the Can-Am Challenge Cup.