Brough Superior 11.50

The Brough Superior 11.50 was a sidevalve V-twin motorcycle made by George Brough in Nottingham, England, designed mainly for sidecar work and for police use. It used a J.A.P. engine of 1,096 cc with the cylinders set at sixty degrees. Its name came from the tax horsepower rating of the engine, 11 on the Royal Automobile Club scale and 50 for the claimed brake horsepower, although the engines in reality produced under 30 bhp. About 308 were manufactured from 1933 to 1940, and the model became a favourite for pulling a sidecar. The Wikipedia history explains the rating formula, in which the piston diameter squared is multiplied by the number of cylinders and divided by 2.5, a figure that manufacturers needed to state for tax purposes.