1925 Bentley 3 Litre

After designing aero-engines for the R.A.F. in World War I, Walter Owen Bentley redirected his attention to motor cars. W.O. was a railway engineering apprentice he later became an aero-engine designer, before introduction his immortal 3-Litre model in October of 1919 at the London Motor Show. The production version did not become available for another two years. The 2,966-cubic centimeter four-cylinder model proved to be very popular, and over 1,600 examples (published figures have stated 1613, 1622, 1624, 1636) examples were built in three wheelbase configuration and three performance levels, including 513 Speed Models which wore a distinctive red radiator badge, or 'Red Label.' They were renowned for their performance and unrivaled quality, with the list of approved coachbuilders totaling over 100. The majority were bodied by Vanden Plas with either open tourer or saloon coachwork. After receiving coachwork, the vehicles were then inspected by the company before allowing them to be sold, and each 3-Liter received a five-year guarantee.

The long-stroke four-cylinder unit had an 80mm bore and 149mm stroke, with a five-bearing crankshaft, shaft-driven overhead camshaft, Twin ML magnetos provided the ignition, monobloc construction, aluminum pistons, and four valves per cylinder. It prioritized torque over top-end power, and produced between 65 hp and 88 hp. It was backed by a separate four-speed gate-change gearbox and was delivered to customers in bar chassis guise only, albeit with a choice of wheelbase lengths and engine tune. The pressed-steel chassis started off with a wheelbase of 9' 9½' (the 'short standard') then adopted dimensions of 10' 10' ('standard long') in 1923. Rear-wheel brakes only were employed up to 1924 when four-wheel Perrot-type brakes were introduced.

Production continued until 1929 earning numerous victories along the way. They won the Whitsun Brooklands Meeting on May 16th of 1921 and earned the Team Prize at the Tourist Trophy on the Isle of Man a year later after finishing second, fourth and fifth. Proud of their accomplishment, Bentley published a celebratory booklet entitled 'The Blue Riband' and introduced a commemorative 'T.T. Replica' built on the 'short standard' chassis. Identified by the Red Label on its radiator, this Speed Model differed by having twin SU 'sloper' carburetors, a higher compression ratio, different camshaft and the close-ratio A-type gearbox, the latter being standard equipment prior to 1927 when the C-type 'box was adopted. With the engine offering 80 horsepower, the top speed increased to an impressive 90 mph. Other competition enhancements included a larger (11-gallon) fuel tank and many received André Hartford shock absorbers.

Captain John Duff and Frank Clement drove a 3-Litre Bentley to fourth place overall during the inaugural 24-hour race at Le Mans on May 26th-27th 1923. The 'T.T. Replica' would evolve into the 'Speed Model' that same year, and would go on to achieve outright Le Mans 24-hour victories.

The standard model was the 'Blue Label' which rested on a 117-inch wheelbase from 1921 to 1929 or a long 130-inch wheelbase platform offered from 1923 to 1929. The 'Red Label' and 'Green Label' were produced from 1924 to 1929, with both powered by high compression engines. The Red Label had a 5.3:1 compression ratio while the Green Label had a 6.3:1 compression ratio. The Red Label rested on a 117.5-inch wheelbase while the Green Label measured 108-inches.

While production figures vary, it is believed that three experimental chassis were built, along with 1,088 regular production examples, 513 Speed models, and 18 Super Sports (for a total of 1,622). The oldest surviving production Bentley is 3 Liter chassis number 3 wearing coachwork by UK coachbuilder R. Harrison & Son.

by Daniel Vaughan | Oct 2021