Happy 60th birthday to Bentley’s 6¾-liter V-8
Long after its financially-exhausting international racing program put engine master W.O. Bentley’s company into Rolls-Royce’s hands, the team operating in Crewe at Rolls-Royce’s former aero-engine factory was tasked with the development of a new eight-cylinder that would suit both brands.
Starting in 1952, with the work led by senior engine designer Jack Phillips, it took seven years to finalize the initial 5.2-liter prototype V-8 into the production as a 6.2-liter in the 1959 Rolls-Royce Silver Cloud II and Phantom, as well as the Bentley S2 Series. The Rolls-Royce–Bentley L-series then went through a number of evolutions, yet the Bentley side always pushed its engine further, turbocharging the Mulsanne in 1982, and then gaining exclusivity to the 6¾-liter once Rolls-Royce switched to BMW V-12s in 1998.
To make sure that the new eight-cylinder was fit to replace the six-cylinder used in the Mark VI, R-Type, and S1, Bentley tested the V-8 over hundreds of thousands of miles in the toughest conditions, as well as at full throttle for 500 hours. And the benefits were clear. Not only was the V-8 30 pounds lighter, but it also produced all the power and torque the British luxury brands could ever dream of, allowing for air conditioning and power steering in 1959.
Bentley has redesigned the V-8 for the T-Series in 1965, increasing its stroke from 3.6 to 3.9 inches for a total displacement of 6¾-liters. In 1980, emission and safety regulations required the introduction of a collapsible water pump, which shortened the engine by four inches. Then came the Mulsanne Turbo for 1982, becoming Bentley’s first forced-induction model since the Blowers of the 1920s. Once the single turbo got replaced by a twin-turbo system with fuel injection, Bentley’s output figures climbed above 500 horsepower and 740 lb.ft of torque.
With 35,898 V-8s produced in Crewe since 1959, Bentley’s 6¾-liter still requires 15 hours to build by hand by a selected few technicians. And while the current Mulsanne only shares its “basic principles and dimensions” with the 1959 Bentley S2’s L-Series engine, that stone set design still makes this V-8 the world’s longest-serving in production.
And at the age of 60, its most advanced evolution in the nose of the Bentley Mulsanne Speed still feels rather fresh, developing 530 horsepower and 811 lb-ft of torque for a top speed of 190 mph in perfect comfort. As Bentley has been saying since 1959, you just get a “wave of torque.”