After finding only modest success with the supercharged 125 F1 car in Formula One, Ferrari decided to switch for 1950 to the naturally aspirated 4.5-litre formula for the series. Calling in Aurelio Lampredi to replace Gioacchino Colombo as technical director, Enzo Ferrari directed that the company work in stages to grow and develop an entirely new large-displacement V12 engine for racing.

The first outcome of Lampredi's work was the experimental 275 S. Just two of these racing barchettas were built, based on the 166 MM but using the experimental 3.3-litre V12. These were raced at the Mille Miglia of 1950 on April 23. Although one car held the overall lead for a time, both were forced to retire with mechanical failure before the end.

The 275 F1 made its debut at the Grand Prix of Belgium on June 18, sporting the same 3.3-litre (3322 cc/202 in³) version of Lampredi's new engine. With three Weber 42DCF carburetors, a single overhead camshaft for each bank of cylinders, and two valves per cylinder, the engine produced a capable 300 hp (224 kW) at 7200 rpm. Alberto Ascari drove the car to fifth place, marking the end of the 3.3-litre engine.

The 275 was replaced at the Grand Prix of Nations at Geneva on July 30, 1950 by the 340 F1. As the name suggests, the car sported a larger 4.1-litre (4101.66 cc/250 in³) version of Lampredi's V12. Other changes included a new de Dion tube rear suspension based on that in the 166 F2 car and four-speed gearbox. It had a longer 2,420 mm (95 in) wheelbase, but other dimensions remained the same. With 335 hp (250 kW), Ascari was able to keep up with the Alfa Romeo 158 of Juan Manuel Fangio but retired with engine trouble. Although the 340 proved itself capable, it was only the middle step in Ferrari's 1950 car development.

...
Wikipedia