Semi Elliptic.net

Car : Sunbeam 20 HP
Year : 1930
Engine : 6 cylinders in line
Bore and stroke : 75×110 mm
Cylinder capacity : 2992 cc
Gears : 4 forward
Brake horse power :55
Maximum speed : 76 mph
Wheelbase : 10 ft 4½ ins (3.16 m)
Suspension : front and back : semi-elliptic leaf- springs
Sunbeam 12-16 HP
Sunbeam 20 HP
The problem of just how useful racing is to technical progress has provoked much debate even as far back as 1913. Louis Coatalen, designer of the 12-16 HP, was convinced that competitions stimulated progress. Coatalen, however, owed his reputation to racing, thanks to the cars he designed and developed. The 12-16 HP was a good example of how racing necessitated modifications. In 1911, when it appeared on the market, it had a 2412 cc engine (bore and stroke: 80×120 mm), but for the Coupe de l’Auto in 1912 Coatalen adapted several engines, keeping the bore the same, but increasing the piston stroke to 150 mm for a total cylinder capacity of 3016 . Thereafter all cars in the 12-16 series incorporated this engine. Later, still because of competitions, the stroke was reduced again, to bring the car within the 3000 cc class. 1,700 vehicles were built by the company in 1913.
The 1925 Sunbeam marked the beginning of the end for the firm, precisely because it was too involved with racing–although the 20 HP was positive proof of the validity of the experiments carried out on the circuit. Yet while the racing engine developed almost 90 bhp, guaranteeing a maximum speed of around 90 mph (the car could do around 50 mph in second, and over 70 mph in third) , the touring version could manage barely 50 bhp at 3,600 revs , a rather low amount in relation to the cylinder capacity even for those days. Record-breaking not just on the race-track, this version played an important part in the firm’s history; but it was these sporting interests that in the end brought about the company’s down-fall.