Alfa Romeo 6C

The Alfa Romeo 6C name was used on road, race, and sports cars produced between 1927 and 1954 by Alfa Romeo; the "6C" name refers to the six cylinders of the car's straight-six engine. Bodies for these cars were made by coachbuilders such as James Young, Zagato, Touring Superleggera, Castagna, and Pinin Farina. Beginning in 1933 there was also a 6C version with an Alfa factory body, built in Portello. In the early 1920s Vittorio Jano received a commission to create a lightweight, high performance vehicle to replace the Giuseppe Merosi designed RL and RM models. The car was introduced in April 1925 at the Salone dell' Automobile di Milano as the 6C 1500. It was based on Alfa's P2 Grand Prix car, using a single overhead cam 1,487 cc in-line six-cylinder engine, producing 44 horsepower. In 1928 the 1500 Sport was presented, which was the first Alfa Romeo road car with double overhead camshafts.

6C 1500 (1927–1929)

In the mid-1920s, Alfa's RL was considered too large and heavy, so a new development began. The 2-litre formula that had led to Alfa Romeo winning the Automobile World Championship in 1925, changed to 1.5-litres for the 1926 season. The 6C 1500 was introduced in 1925 at the Milan Motor Show. Series production started in 1927, with the P2 Grand Prix car as a starting point.The Alfa Romeo 6C-1500 Super Sport features a twin overhead cam six cylinder engine with a bore of 62 mm and stroke of 82 mm, giving a displacement of 1487 cc, as against the P2's 1,987 cc, while supercharging was dropped. First versions were bodied by James Young and Carrozzeria Touring.

In 1928, the 6C Sport model was released, with a dual overhead-camshaft engine. Its sport version won many races, including the 1928 Mille Miglia. Total production was 3,000 (200 with DOHC engines). Ten examples of a supercharged (compressore, compressor) Super Sport variant were also built.[1]

6C 1750 (1929–1933)

The more powerful 6C 1750 (1,752 cc, 65 x 88 mm) was introduced in 1929 in Rome. The car had a top speed of 95 mi/h, a chassis designed to flex and undulate over uneven surfaces, as well as sensitive geared-up steering.[3] It was produced in six series between 1929 and 1933. The base model had a single overhead cam. Super Sport and Gran Sport versions had a double overhead cam engine (DOHC). Again, a supercharger was available. Most of the cars were sold as rolling chassis and bodied by coachbuilders such as Zagato, and Touring Superleggera. Additionally there were 3 examples built with James Young bodywork, one of which is a part of the permanent collection at the Simeone Foundation Automotive Museum in Philadelphia, PA, USA, in original and unrestored condition.[3]

In 1929, the 6C won every major racing event in which it was entered, including the Grands Prix of Belgium, Spain, Tunis and Monza, and the Mille Miglia was won by Giuseppe Campari and Giulio Ramponi. The car also won the Brooklands Double Twelve and the Ulster TT. In 1930 the car again won the Mille Miglia and Spa 24 Hours.[4]

6C 1900 (1933)

The Alfa Romeo 6C 1900 was the final derivative of the original 6C 1500, produced in 197 examples during 1933 as a transitional model, before the new 6C 2300 was introduced the following year. Only built in Gran Turismo guise with a 2,920 mm wheelbase, the 6C 1900 replaced the corresponding 6C 1750 model. Besides the larger displacement, other notable mechanical changes were aluminium cylinder heads, an improved chassis frame and a new transmission. The same upgrades were applied to the 1933 model 6C 1750 Gran Sport which, together with the 6C 1900, form the sixth series of the 6C. Alfa Romeo offered the 6C 1900 with an in-house 4-door saloon body, while bespoke coachbuilt body styles included 4-seater cabriolets.

The double overhead camshaft, naturally aspirated, straight-six engine was bored out from 66 mm to 68 mm, bringing displacement to 1917 cc. For the first time on a 6C the cylinder head was aluminium; some engines were also manufactured using an aluminium block with pressed-in steel sleeves in place of the usual cast iron block. With 68 hp-metric at 4,500 rpm the 6C 1900 could achieve a top speed of 130 km/h. The improved chassis frame consisted of fully boxed rails and crossmembers, instead of the 1750's C-shaped sections. A new four-speed gearbox was fitted, with synchromesh on the two top gears and a freewheel mechanism.

6C 2300 (1934–1938)

The 6C 2300 (2,309 cc, 70 x 100 mm) was designed by Vittorio Jano as a lower-cost alternative to the 8C. In 1934 Alfa Romeo had become a state-owned enterprise. That year, a new 6C model with a newly designed and larger engine was presented. Chassis technology, however, had been taken from the predecessor. One year later a revised model, the 6C 2300 B, was presented. In this version the engine was placed in a completely redesigned chassis, with independent front suspension and rear swing axle, as well as hydraulic brakes. 760 examples of the rigid-axle 6C 2300 were produced and 870 examples of the B-model.

6C 2500 (1938–1952)

Introduced in 1938, the 2500 (2,443 cc) was the final 6C road car. World War II was coming and car development was stopped, but a few hundred 6C 2500s were built from 1940 to 1945. Postwar, the first new Alfa model was the 1946 6C 2500 Freccia d'Oro (Golden Arrow), of which 680 were built until late 1951, with bodies by Alfa. The 2500 had an enlarged engine compared to the predecessor model; this Vittorio Jano designed dual overhead cam engine was available with either one or three Weber carburetors. The triple carburetor version was used in the top-of-the-range SS (Super Sport) version. The 2,443 cc straight-six engine was bored out from 70 mm to 72 mm and was mounted onto a steel ladder frame chassis, which was offered with three wheelbases: 3,250 mm on the Turismo, 3,000 mm on the Sport and 2,700 mm on the Super Sport. Various coachbuilders built their own bodied versions of the 2500, but most bodywork was built by Touring Superleggera of Milan.[13]

The Tipo 256 was a racing version of 2500 made in eight examples between 1939 and 1940 for the Mille Miglia and the Le Mans 24 Hours.[13] It was made in Spider (convertible) and Berlinetta (coupe) Touring bodystyles. With a power of 125 bhp it could achieve a top speed of 200 km/h.[14]

The car was sold to wealthy customers like

6C 3000 (1948–1954)

In 1948, a first Alfa Romeo 6C 3000 prototype was built. It was a 5–6 passenger 4-door saloon car of the same class as the 6C 2500, but which could be built using more modern and economical manufacturing processes.

Like its predecessor, the three-litre engine had a cast iron block, an aluminium head with hemispherical combustion chambers, two valves per cylinder, angled 90° and timed by directly acting, chain driven dual overhead camshafts. Fed by a twin-choke carburettor, it developed 120 PS, sent to the rear wheels through a 4-speed all-synchromesh gearbox with a column-mounted shifter as on the 6C 2500. The car used unit body construction, had a wheelbase of 3.05 m and a dry weight of 1,400 kg. The all-independent suspension was of the double wishbone type with coil springs upfront, and trailing arm type with transverse torsion bars at the rear.

After three prototypes had been made between 1948 and 1949, the project was abandoned when market analysis and product planning suggested the development of a smaller four-cylinder car—the Alfa Romeo 1900. Despite this, the 3-litre engine was developed for competition use and gave birth to a number sports racing cars during the first half of the 1950s: the 6C 3000 C50, 6C 3000 CM and 6C 3000 PR.

Technical data

Bibliography

External links

• Registro Internazionale Alfa Romeo 6C 2500
• All Alfa Romeo 6C models chronologically listed