The supercharged 1.5-liter Maserati 4CL engine was designed in 1939 by Ernesto Maserati and did not achieve much before the war broke out. After the war the Maserati firm had changed completely. It had been moved to Modena by Adolfi Orsi and the Maserati Brothers had become consultants, leaving Alberto Massimino as technical director. When the war ended Scuderia Milano was established by Arialdo Ruggeri and Arnaldo Mazzuchelli and they decided to use pre-war machinery, acquiring the 4CLs from Orsi. These were upgraded in the post-war years and fitted with two-stage supercharging in 1948. The success of Alfa Romeo and the increasing competitiveness of Ferrari mean that Maserati scaled back its sporting activities and in 1949 Scuderia Milan approached Mario Speluzzi, who had been developing Maserati engines for powerboats, and asked him to develop the old four-cylinder. The resulting engine was called a Speluzzi and it appeared in 1950 in the hands of Felice Bonetto at the French GP. A week later Clemente Biondetti finished sixth in the Italian event at Bari but he was five laps behind. The engine was also run by Gianfranco Comotti later in the year but ti was clear that it was not going to be able to compete with more modern machinery and at the end of the year the program faded away.