Maserati 4CL and 4CLT

In the late 1930s, continued rapid development in the increasingly competitive international voiturette class, and the introduction of the Alfa Romeo 158 and ERA B- and C-type models, forced the Maserati brothers into designing a new, square-bore,inline-4-cylinder engine, with a bore and stroke of 78 mm for a total displacement of 1,490.85 cc (1.5 L). This new engine developed 30–50 bhp more than the previous inline-6, the increase mostly achieved through an increase to four valves per cylinder, coupled to the use of a more powerful supercharger and a small increase in the compression ratio. Following customary Maserati practice, the engine was mounted into a chassis design almost identical to that of the 4CL's predecessor: the Maserati 6CM. Conventional in its architecture, twin box-section spars ran the length of the car joined, ladder-fashion, by smaller cross members, although the 4CL design did incorporate more aluminium componentry than its forebear. Although near-identical in its wheelbase, the 4CL's track was a full 5 cm (1.97 in) wider than the 6CM, and sat lower thanks to repositioned spring hangers.

A 1939 Maserati 4CL

Enveloping this rather conservative chassis was a low, curvaceous alloy-panel body, built in-house by Maserati. Maserati also built a streamlined version of the 4CL from the outset. Continued engine development, in response to Alfa Romeo's post-war introduction of two-stage supercharging, began to expose weaknesses in the chassis design. In an attempt to improve torsional rigidity Maserati began to experiment with tubular section chassis members. These experimental models ran alongside conventional 4CLs throughout the 1947 season, and eventually led to the introduction of the 4CLT in 1948.

A Maserati 4CL at Oulton Park circa 1982

4CL Streamliner at Tripoli Grand Prix on 7 May 1939, where it quickly broke down, driven by Luigi Villoresi (1909–1997).

In the hands of Luigi Villoresi the streamliner took pole position on the 4CL's race debut at the 1939 Tripoli Grand Prix, ahead of Mercedes' brand new W165s. However, both it and two of the three conventional 4CLs entered retired early in the race with engine troubles, leaving the Silver Arrows to take the victory. Embarrassingly for the works team, following this disappointing debut the 4CL's first taste of victory came in the hands of privateer Johnnie Wakefield at the Naples Grand Prix, two races later. Through the remainder of 1939 voiturette races Wakefield took two further victories, and the works' 4CLs picked up another two, before the outbreak of war curtailed international competition. Villoresi took the 4CL to victory in the 1940 Targa Florio, but with entry restricted to Axis countries, and only Maserati fielding a factory team, the opposition was hardly world class.

On the resumption of competition in 1946 the Maserati 4CL proved the class of the field. Luigi Villoresi immediately returned to winning ways, taking victory in the first race following the cessation of hostilities: the 1946 Nice Grand Prix. Tazio Nuvolari and Giorgio Pelassa both took wins in 4CLs, but it was Raymond Sommer and his 4CL who dominated the season. 1947 would prove to be the 4CL's most successful season and, despite Alfa Romeo fielding the revamped 158 and new 308, Maserati drivers picked up 10 individual race victories.

Maserati 4CL

After the replacement of the factory team's 4CLs by the new 4CLT, many examples of the older cars found their way into privateer hands. It was owing to the 4CL's popularity with privateer entrants that many were still being run in top-flight competition at the outset of the Formula One World Championship in 1950.

The first variant of the 4CLT earned its "Sanremo" nickname from the first race for which it was entered: the 1948 Sanremo Grand Prix. The name stuck, as Alberto Ascari took his 4CLT to victory in its maiden race appearance. A portent of things to come, Villoresi and Reg Parnell won five of the 1948 season's remaining races. In the first year of the Formula One World Championship, a Sanremo scored what was to be the Maserati's best Championship finish, when Louis Chiron took third place at his home Grand Prix: the 1950 Monaco Grand Prix. The last 4CL variant to compete in the World Championship was a 4CLT/48 modified by the Arzani-Volpini team, that failed to even qualify for the 1955 Italian Grand Prix.

For 1949, minor modifications to the brake drums, switching from vanes to slits for cooling, along with small changes to the cockpit control layout and a repositioned oil header-tank resulted in a car sometimes referred to as the 4CLT/49. It was never known as such by the factory. The Ascari/Villoresi/Parnell trio, joined by Juan Manuel Fangio and Toulo de Graffenried, took up where they had left off the previous season, winning nine of the first fifteen races of 1949, including de Graffenried's victory in the British Grand Prix. However, the second half of the season only saw three further wins, as increasingly competitive Ferrari and Talbot cars squeezed out the Maseratis in most major races.

1950 saw the introduction of the FIA World Championship of Drivers. In response to improvements to the Alfa 158 and the already competitive Ferrari and Talbot, Maserati again upgraded the 4CLT's engine. A multi-part crankshaft, lightened and balanced rods, a more powerful pair of superchargers and changes to the ignition timing took engine output up to a claimed 280 bhp (209 kW).[1] Coupled to shedding 10 kg (22 lb) from the car's weight, this brought the Maserati up to near-Alfa levels of performance. Although moderately competitive in short runs, the final upgrades proved to be too much for the decade-old powerplant's design and the 4CLT's Grand Prix performance was hindered by engine failures. The season's only Formula One wins came in non-Championship events. Fangio won the Pau Grand Prix on the same day as Parnell took the Richmond Trophy at Goodwood. David Hampshire won the Nottingham Trophy later in the year. Fangio also won the Formula Two Ramparts Grand Prix, at Angoulême, in a 4CLT chassis fitted with an A6GCM engine. The Milano team modified a 4CLT for use in 1950 and 1951, but without success.

Also for 1951 B. Bira modified his '49-spec 4CLT to accept a more powerful, 4,450 cc (271.6 cu in), naturally aspirated OSCA V12 engine. This engine developed around 300 bhp (224 kW).[2] With it Bira won the Goodwood race early in the season, but in its only World Championship appearance, at the 1951 Spanish Grand Prix, it retired on the first lap.

In late 1949 a number (two or three, depending on source) of the remaining Sanremo cars were converted for use in the Temporada series Formula Libre races in Buenos Aires, Argentina, in the 1949 to 1950 summer season. This model was referred to as the 4CLT/50; although that name is sometimes also applied to the 1950-specification Formula One cars, the Temporada cars are the only ones that were referred to as such by the factory. The modifications were mostly restricted to enlargement of the engine capacity to 1,719 cc (104.9 cu in).[1] Despite these improvements the series was dominated by Ferrari, and following the final race the cars were shipped back to Italy and reconverted to Formula One specifications.

A long term campaigner of Maserati automobiles, Enrico Platé recognised the Maserati's shortcomings as a Formula One vehicle, and converted a 4CLT/48 into the Maserati-Platé 4CLT Formula Two variant. As F2 was for naturally aspirated cars, the first step was to remove the superchargers. After this, to counteract the resulting loss in performance, the compression ratio was more than doubled and capacity was upped to the class limit of 2.0 L (122.05 cu in). With the lower power output from the revised engine, weight was shed and handling sharpened by reducing the wheelbase.

De Graffenried won the Richmond Trophy, and Giuseppe Farina the Paris Grand Prix, in 1951, but with the switch to Formula Two rules for the World Championship from 1952 onwards, the old 4CLT chassis were found to be overweight and underpowered in comparison to their newer rivals. Despite having been the mainstay of top-flight racing since the end of the 1930s, the 4CL and 4CLT rapidly fell from favour, as smaller and lighter machines began to emerge from European factories still recovering from the effects of war.

Today, many 4CL and 4CLT models survive and are regularly campaigned in historic motorsport events, as well as being on static display in museums.