The 860 Monza was the final evolution of a series of four-cylinder sports racers that Ferrari had developed since 1953. The company's shift to inline-four engines for its sports car programme had begun alongside its Formula One four-cylinder effort, with the resulting engine family producing competitive, reliable cars that ran through the 625 TF, 735 S, 750 Monza, and 857 S before reaching the 860 Monza.
The 860 Monza emerged from the 857 S of 1955, which had been built to challenge the dominant Mercedes-Benz 300 SLR but proved unable to match the German car. For 1956 Aurelio Lampredi reworked the engine, specifying dimensions of 102 mm bore by 105 mm stroke for a total capacity of 3,431.93 cc; power output remained at 280 PS. Despite the similar displacement and power figure, the revised engine was considerably more competitive in practice.
The chassis received a wheelbase extension of 100 mm compared to most Monza variants, stretching to 2,350 mm — matching the 500 TRC rather than the 2,250 mm shared by most of the Monza family. A new front suspension layout using coil springs, also adopted on the concurrent 500 TR, was fitted. The car was approximately 100 kg heavier than the 857 S but handled well owing to the revised suspension geometry.
The 860 Monza competed at the front of the 1956 World Sportscar Championship. At the 1956 12 Hours of Sebring, Juan Manuel Fangio and Eugenio Castellotti won the race outright, with Luigi Musso and Harry Schell scoring second place — a commanding Ferrari one-two with the 860 Monza. At the 1956 Mille Miglia, two 860 Monzas finished second and third overall, further demonstrating the car's competitiveness over the full range of circuit and road race formats.
The 1956 season unfolded against a changed competitive landscape. Mercedes-Benz had withdrawn from international sports car racing at the end of 1955, removing the primary threat that had suppressed Ferrari in that year's championship. With the 860 Monza and the new 290 MM V12, Ferrari was well positioned to reclaim the World Sportscar Championship, which it duly won. Jaguar's new D-Type took the Le Mans 24 Hours victory under revised ACO regulations that restricted large-displacement prototypes, and Maserati's 300 S won the 1000 km Nürburgring, but Ferrari accumulated sufficient points across the season for the championship.
The four-cylinder Ferrari Monza family had been notable for its inline engine configuration, which led to different carburetor placement compared to Ferrari's V12 models. Where V12s used downdraft carburettors located in the engine valley, the four-cylinder cars used side-draft units, eliminating the need for hood scoops and producing a distinctive silhouette.
At the end of 1956 Ferrari retired the four-cylinder sports racer concept from its works programme, turning to Jano V12-powered cars — the 315 S and 335 S — and the Colombo V12-powered 250 Testa Rossa for the 1957 factory effort. The 860 Monza thus stands as the final works development of the Lampredi four-cylinder sports racer line that had contested the World Sportscar Championship since 1953. Customer racing of the associated 500 TRC — which shared the 860 Monza's 2,350 mm wheelbase — continued into 1957 and beyond.
The 860 Monza's Sebring victory, achieved with Fangio behind the wheel, ensured the car a prominent place in Ferrari's mid-1950s racing history. Its role in the 1956 World Sportscar Championship title marked a fitting endpoint for the four-cylinder Monza programme, which had maintained Ferrari's competitiveness across three seasons of intense international sports car competition.