1927 Bentley Speed Six

History

The Bentley 6.5 Litre was a continuation of the Litre series Walter Owen Bentley had created. The four-cylinder 4.5-liter unit used in the 4½ Litre was used for the 6½ Litre Bentley but the 6½ Litre Bentley had two extra cylinders. The Bentley stright-6 had a cast-iron block and head with an overhead camshaft having four-valves per cylinder. There were two spark-plugs per cylinder. The 100 mm bore and 140 mm stroke resulted in a displacement size of 6597. Horsepower was in the neighborhood of 180 - 200.

The design was based on the Bentley 3Litre but inspired by the Rolls-Royce Phantom I. There were a variety of chassis sizes available that ranged from 132 inches to 152.5 inches.

In 1928 Bentley introduced the Speed Six which would, in time, become the most successful Bentley racer. Woolf Barnato, Tim Birkin, and Glen Kidston drove the Speed Six to victories at the 1929 and 1930 24 Hours of Le Mans.

In total there were 363 examples of the Bentley 6½ L and 182 examples of the Speed Six.

By Daniel Vaughan | Dec 2006

The Bentley Company was created by Walter Owen and Henry Bentley in 1919. Within a few years they had their first 24 Hours of LeMans victory. The company prospered for a number of years before going into receivership in 1931. The company had created a total of 3033 cars and had won victories at LeMans five times.

The litre series engines began in 1919 with the four-cylinder 3-litre unit. For its day, it was very technically advanced, thanks, in part, to the technical abilities of WO Bentley. The engine had dry sump lubrication and an overhead camshaft which operated four valves per cylinder. The use of aluminum pistons was also ahead of its time. In an effort to reduce gasket leaks the entire cylinder block was cast as one piece. The displacement size was increased during the early 1920s culminating to the 6-litre Bentleys. This new model, announced in 1925, had a displacement size of nearly 6.6 liters from the new six-cylinder engine. It drew inspiration from the 3-litre units that had brought many victories to the company. During 1925 and 1926 the Six-Litre Bentley's had mild success on the racing circuit as these seasons were plagued with bad luck for Bentley. In response, Bentley began work on a performance version.

The new special model was ready by 1928 and dubbed the Bentley 6 1/2 Litre Speed Model, also known as the Speed Six. The true potential of the Speed Six was experienced during the 1929 and 1930 LeMans race where the Bentley Speed Six models dominated the race. The drivers and co-drivers who piloted the machines to victory were Woolf Barnato, Tim Birkin, and Glen Kidston.

Success at LeMans was due to many factors including expericne, knowledge, and a durable 200 horsepower engine. The company looked poised to be a strong competitor at LeMans in 1931 but financial difficulties kept them from competition.

The Bentley Company was later bought by Rolls Royce and the proud and historic racing program was discarded.

By Daniel Vaughan | Oct 2006