Bentley announced in early June it is discontinuing the 61-year run of its L-Series 6.75-L V8, an engine architecture the company said has been “in production for more than 60 years, and with the same configuration and bore spacing as the very first version from 1959.” The final engine will power a commemorative version of its flagship, the Mulsanne 6.75 Edition by Mulliner. The Mulsanne model is closing its production run concurrently with the L-Series V8.
Bentley said some 36,000 copies of the L-Series were produced since the engine’s debut in 1959. The last example was hand-built by a team of seven at the company’s assembly plant in Crewe, U.K. “Our venerable 6¾-litre V8 has powered the flagship Bentley for more than six decades, and so has earned its retirement. I am extremely proud of the generations of skilled craftspeople that have meticulously assembled every one of these engines by hand over the years,” said Peter Bosch, Bentley member of the board for manufacturing.
For Bentley, a new generation of propulsion is being prepped and the longstanding Mulsanne also makes way for the future. “The Mulsanne’s role as Bentley flagship will be taken by the new Flying Spur, powered by Bentley’s 6.0-litre twin turbo W12 engine with 626 bhp,” a Bentley spokesperson told SAE International.
“Looking further ahead,” he added, “the retirement of the 6¾-litre is a small step on our journey to electrification, with all Bentley models to be available with a hybrid option by 2023 and a full electric Bentley by 2025.” Bosch said the company can “look forward to the future of Bentley, powered by our exceptional W12, sporting 4.0-litre V8 and of course our efficient V6 Hybrid – the start of our journey to electrification.”
Although engine configuration and unchanged bore spacing underlie Bentley’s claim to the longest-running production engine, some might say engineering semantics would argue for the General Motors small-block V8, introduced in 1955, for which the company has over decades taken pains to retain the engine’s original 4.4-inch (111.8) bore spacing. Regardless of which original design fundamentals are given credence, Bentley admits that, just like GM’s small-block V8s, virtually no single part of the L-Series is related to any used for the original.
The L-Series replaced an inline 6-cylinder for Bentley, and in its first iteration in the 1959 Bentley S2 generated “around” 180 hp. The intent was to double in the I-6’s power output, add no extra weight – it ended up 30 lb (13.6 kg) lighter – and require no additional underhood space, which led Jack Phillips the company’s senior engine designer, to the vee configuration.
The original displacement was 6.2-L, expanding to the now-iconic 6.75-L in 1971 via a stroke increase from 3.6 inches (91 mm) to 3.9 inches (99 mm). In its final twin-turbocharged configuration for the 30-vehicle run of Mulsanne 6.75 Edition by Mulliner models, the 6.75-L V8 generates 530 hp and 811 lb-ft (1100 Nm). The company said the engine laid claim for a time as the highest-torque automotive production engine in the world.Continue reading »