The designation 166 refers to the (rounded) displacement of a single cylinder, which corresponded to the nomenclature of the company at the time.
The abbreviation FL stands for Formula Libre, which is the type of category and racing series that the car competed in.
[1] As race director at Alfa Romeo, Enzo Ferrari was successful in all major competitions.
The aim was to equip the entire future Ferrari range of vehicles, including a sports racing car and a Grand Prix monoposto, with this engine.
[2] The Ferrari 166 FL was developed to take part in races in the "Formula Libre series", which was extremely popular in South America at the time and had a broad set of rules.
Entered that year by Scuderia Ferrari, with Juan Manuel Fangio at the wheel in the Monza Grand Prix on 26 June, the 166 took a debut win.
The vehicle was repainted in the Argentine racing and national colors of blue with a yellow engine cover.
Later that season the car was fitted with a Roots supercharger and entered under the designation FL in several Formula Libre races in South America by Fangio and Benedicto Campos.