2020 Bentley Mulsanne 6.75 Edition by Mulliner Image source: Bentley Motors
Bentley applied what it termed Aero Design Standards (ADS) to the development of its V8 engine in the 1950s, an approach that contributed to the amazing longevity of the company’s 6.75-liter V8 engine, which debuted in 1959. “Both the construction and design of block was quite advanced for its time,” asserted Tim Seipel, functional manager for Bentley’s V-engine calibration.
Bentley and Rolls-Royce were combined companies at that time, and the famed Rolls-Royce Merlin V12 engine in the Supermarine Spitfire and North American P-51 Mustang both used that engine to great effect during World War II. Afterward, the engineering department continued to apply the same high engineering standards to engines designed for less mission-critical applications, such as serenely motoring to the country club.
Image source: Bentley Motors
The arrival of Bentley’s amazing Flying Spur luxury sedan last year spells the end for the Mulsanne, the brand’s previous posh flagship. When Mulsanne production ends in a few months, so will end the run of Bentley’s storied 6.75-liter V8 engine. The Flying Spur is powered by the parent company Volkswagen Group’s corporate W8 and W12 engines rather than a hoary English V8 with roots that run back to The War.
This run makes Bentley’s engine the longest-running current V8, despite any protestations that the General Motors small block V8 dates to 1955. While the Bentley engine has naturally evolved substantially over the intervening decades, it debuted as an advanced all-aluminum engine with deep skirts for enhanced rigidity. The small block Chevy boasts those features now, but it did not have them in its original form, so it is far less a continuation of the same engine than is the Bentley.
Image source: Bentley Motors
Bentley will send off the Mulsanne, and the 6.75-liter V8, with a limited-edition run of 30 cars, the Mulsanne 6.75 Edition by Mulliner. Millionaire gearheads will appreciate that these last cars will feature cutaway schematic drawings of the engine on the faces of the clock and small gauges.
In this final iteration, the V8 engine is twin-turbocharged to produce 530 horsepower and, more critically, 811 lb.-ft. of smooth, seamless torque. The original engine was naturally aspirated, and carbureted, with a displacement of 6.25 liters, and produced 183 horsepower and 258 lb.-ft., demonstrating the advancement of technology over the intervening 61 years.
Even more incredible is the reduction in pollution from the engine at the same time. The early engines produced 7 grams of unburned hydrocarbons per mile, while the rating for today’s engine is 0.09 grams per mile. The Bentley engineering team hypothesizes that the current engine could idle while burning nothing but the exhaust from its predecessor!