Founded in 1899 in Milan (as a result of the fusion of 'Grondona Comi & C' and 'Miani Silvestri & C'), OM (its full name was 'Societa Anonima Officine Meccaniche') made various railway materials amongst other heavy engineering products. In 1918 OM took over the Zust car company and thus obtained a car factory at Brescia in Northern Italy.
The first OM car, the Tipo S305, appeared in 1918 with a 4712cc four-cylinder side-valve in-line engine with 30bhp. This was primarily an old Zust model. A completely new car, the Tipo 465, appeared in 1919, with a 1327cc four-cylinder engine. Generally produced with a four seat torpedo body this was well received and sold in large (for the time) numbers.
This engine was gradually increased in size, first to 1410cc in the Tipo 467 (of 1921) and then shortly afterwards up to 1496cc in the Tipo 469. Both these cars were also built in 'Sport' versions.
1923 saw an all new car, the Tipo 665 'Superba' with an all new 2-litre six-cylinder engine released. This model greatly increased the standing of the company, helped also by its significant successes in motorsport and occasional world record ! Notable were top five positions at Le Mans in both 1925 and 1926 and the 1927 victory of the first Mille Miglia, where OM Superbas filled the first three positions. Development included supercharging and an increase in engine size to 2.2-litres in 1930.
In 1933 the car production facilities were absorbed into the Fiat group. 1934 saw the display of a new car, the Tipo V, with a six-cylinder overhead-valve 2130cc engine, but production did not follow. OM became dedicated to producing commercial vehicles (as part of the Fiat group) until it was absorbed into IVECO in 1975.
Built from 1918 until 1923, this was the first production car to use the OM badge, in reality being a modified old Zust model. It used a 4712cc four cylinder engine with sidevales, coupled to a four speed gearbox. Two wheelbases were produced, 2300mm and 3500mm.
Built from 1919 until 1922, this was the first true new OM. '465' referred to '4' cylinders and a stroke of '65'mm. The engine was an all new 1327cc four cylinder unit whilst the transmission was a three speed item. Again it was available with short (2700mm) and long (2900mm) wheelbases. A single example of an experimental Spider Corsa was also built.
Introduced in 1921, the 467 (4 cylinder 67mm stroke) used an increased capacity version of the 465 engine (the stroke was increased), now with 1410cc. The three speed transmission remained, whilst the wheelbase was also the same as the earlier car (2700mm). Production continued until 1923.
Produced from 1922 until 1934, the 469 (4 cylinder 69mm stroke) was the longest lived production OM. The engine was again a further development of the original 465 unit, now displacing 1496cc and producing 30bhp @ 3,000rpm. The transmission adopted four gears, whilst the single wheelbase became 2800mm. The track also increased slightly.
The standard model at the beginning was the 469N, at the same time was built the 469S which featured brakes also on the front wheels. Both these models were replaced in 1923 by the 469S2 which featured a further increased track. This continued in production until 1930, when the 469S4 was introduced. This latter used a 1622cc engine (both bore and stroke were increased) and production ran until 1934 when the 469 ceased to be made. From 1932 it featured a further increased track.
Tipo 665 Superba
Probably the most famous OM, the 665 or 'Superba' was built in various versions from 1923 until 1932. Introduced in 1923 were two versions, the 665N and 665S. The main difference was the wheelbase, the 'N' being longer, at 3100mm, the 'S' having only 2800mm. Both cars used a four speed gearbox and a new six-cylinder 1991cc sidevalve engine, with 40bhp @ 3,600rpm in the 'N'. In 1927 both versions received a wider track just before they ceased production. 1928 saw the 665 N3 entering production, essentially an improved 'N', replaced the following year by the 665 N5. 1928 also saw the 665 SMM entering production with a new 2790mm wheelbase. The N5 also used the shorter 2790mm wheelbase and a narrow track with the same 1991cc engine.
1930 witnessed the introduction of a new 2200cc engine with 55bhp @ 4,000rpm into both the 665 N5 and the SMM. The N5 also received a wider track. During 1930 and 1931 there were also built a small number of 665 SS MM Superba Compressore which had the 2200cc engine plus a supercharger.
A single example of this prototype was built, in 1934. It had a 2130cc six-cylinder engine with a strange mix of sidevalves (for the inlet) and overhead valves (for the exhaust). A power output of 65bhp @ 3,800rpm was achieved. A wheelbase of 3,000mm and a three speed gearbox were also used.
Gran Prix 8C
In 1926 and 1927 OM also developed a GP car. This used a dohc eight-cylinder in-line 1496cc engine which was supercharged and produced 120bhp @ 6,000rpm. The wheelbase was 2500mm, the track 1250mm. A total of three of these 200km/h cars were built.
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