The foundation of OSCA
In 1937, five years after Alfieri's death, Ettore and Ernesto Maserati were forced to sell Maserati after financial turmoil. However, the contract with the new Maserati owner Adolfo Orsi meant that the brothers had to remain with their former company for a ten-year term. In 1947 they were finally free to go their own way; Officine Specializzata Costruzioni Automobili Fratelli Maserati was founded and the first vehicle type, the MT4, was built. In its original form, the chassis and engine were based on the Maserati Tipo 4CL single-seater racing car, first built in 1939. Development of the MT4 began immediately, using plans and parts from the Maserati 4CL. In all, OSCA built 77 chassis between 1949 and 1956 (some sources state 72, some 78).
The MT4, for Maserati Tipo 4 cilindri, initially used a Fiat 1100 block and the engine developed 55 hp (40 kW). OSCA soon developed a new 1,092 cc engine, which produced 72 PS (53 kW; 71 hp) at 6,000 rpm, had a in-house designed aluminium block and alloy head. Some sources state that 9 cars were built with 1.1-liter engines. Originally a single-cam design, in 1950 this was changed to a twin-cam unit, indicated by using the name MT4-2AD, with "2AD" signifying 2 Alberi di Distribuzione (twin camshafts). The 2AD was originally available as an 1100 or a 1350. The bore and stroke changed over the years and to allow competing in various classes, meaning that the displacement of the engines increased from 1092 cc via 1342 cc and then 1453 cc until finally reaching 1492 cc. The four-speed quick-shift gearbox was also an in-house design. The bodywork on early models was a two-seater roadster with or without cycle fenders, lights, and the various other accoutrements required to make it street legal. OSCA only supplied the chassis; the bodies were manufactured by Italian bodywork companies (or in some cases, by the buyers themselves) to the requirements of the individual buyers. Modifications and changes to keep cars competitive or due to changes in taste means that few preserved cars look much like each other.
In 1949 the engine was enlarged to 1,342 cc, with power increasing to 80–90 hp (59–66 kW) at 5,500 rpm depending on the tune specified. In 1950, the new DOHC (MT4-2AD) raised power to a maximum of 100 hp (74 kW) at 6,300 rpm for the 1350 engine, and in 1953 the engine was enlarged to 1,453 cc to compete in the 1500 cc class, producing 110 hp (81 kW) at 6,200 rpm. In 1954, this was bored out to a square 78 mm × 78 mm (3.07 in × 3.07 in) for 1,491 cc and fitted with twin sparkplugs. This "proper" 1500 engine produced 120 hp (88 kW) at 6,300 rpm and was aimed directly at the Porsche 550. The bore and stroke of the 1500 engine are the same as those of the Maserati 4CL, also developed by the Maserati brothers.
A period road test found that a MT4-2AD 1500 (chassis number 1148) could reach 120 mph (193 km/h) despite being fitted with the lowest gearing, achieving the 0–60 mph (0–97 km/h) sprint in 7.0 seconds. The listed price was $10,000, enough to buy three V8-engined Ford Thunderbirds with a good margin, but Road & Track stated that the OSCA had outperformed every lower-priced car ever tested by them. The reviewers also remarked on the rarity of an Italian-made car matching the manufacturer's claimed top speed, acceleration, and weight figures. By this time, about half of OSCA's production was earmarked for the United States, with another ten percent being exported elsewhere.
The final iteration was the 1500 TN (for Tipo Nuovo, "new model") engine, tuned to 125 hp (92 kW). The first such engine was installed in the Simpson Special; a record-breaking streamliner on an MT4 chassis which beat numerous land speed records at the Bonneville Salt Flats in 1955. In competition, however, the TN engine was too powerful for the MT4 chassis and the Maserati brothers quickly developed a new, more rigid design also called the 1500 TN. The MT4 design, however, was finally reaching the end of its development. The fragile 1500 TN, while fast, rarely finished and only three cars were built in 1955. Three more, called S 1500 TN were finished for the 1957 season and had another five horsepower.
The OSCA MT4 is best known for the 1954 12 Hours of Sebring, where it won outright against much more powerful cars with drivers Stirling Moss and Bill Lloyd as part of the Briggs Cunningham Team. In the April 6, 1992 issue of AutoWeek, Cunningham stated that, of all the automobiles he built, owned, and raced, the OSCA was his favorite racecar.
Racing history The starts and racing successes of the MT4 are extensive and go beyond the usual framework of sports car models: 449 entries, 939 race starts, 81 overall, and 98 class victories. The first use of an MT4 was in 1948 in the Coppa Acerbo sports car race at Pescara. Driving chassis 1101 was Franco Cornacchia, who failed to finish the race. The MT4's first success came later that year, at the Grand Prix of Naples, where it was driven to a win by Luigi Villoresi. In 1949, Giulio Cabianca won a sports car race in Ferrara and three weeks later a race in Tigullio. The Giro delle Calabria was won by Dorino Serafini and Alberico Cacciari ahead of Luigi Fagioli, who also drove an MT4. From 1950 onwards, the MT4 established itself as a fast racing car that was not prone to defects and was hard to beat in the racing classes with displacements of less than 2 liters. At the Mille Miglia in 1951, Luigi Fagioli won the class for sports cars with displacements of up to 1.1 liters. In the overall standings, he finished eighth, just under an hour behind the winner Villoresi in the Ferrari 340 America Berlinetta Vignale. Cabianca repeated the class win in 1952. In the same year, the model was driven for the first time in the 24 Hours of Le Mans. Mario Damonte and a French racing driver using the pseudonym Martial drove a Vignale-bodied 1.3-liter MT4. Their race ended after 19 hours of driving due to a damaged clutch. With the start of the sports car world championship in 1953, MT4s were also used there. After countless successes at national races in Europe and the United States, 1954 saw the greatest international success for an MT4. At the 12 Hours of Sebring, Stirling Moss and Bill Lloyd won the general classification for Briggs Cunningham's team. To date, it is the only overall victory for a sports car with a displacement of less than 1.5 liters in this long-distance race. The light and maneuverable racing cars were often on a par with the high-capacity cars, especially on narrow and winding courses. This was evident, for example, at the 1956 Mille Miglia, where Cabianca and Umberto Maglioli fought for the lead in the early stages of the race with the Ferrari and Maserati works drivers. Gianfranco Stanga celebrated the last race victory with an MT4 at the Campagnana Vallelunga in 1961, ahead of an OSCA S1000 and a number of Etceterini. The last known use outside of historical races was in 1966 in the sports car world championship. Giuseppe Rossi finished 38th overall and won the class for prototypes with a displacement of up to 2 liters at the Mugello 500 km race.
This article is based on the Wikipedia article "OSCA MT4" as of April 29, 2026.