Rolls-Royce – Bentley L Series V8 engine

1959 on

The Rolls-Royce – Bentley L Series V8 engine was introduced 1959 and is still in production. Built in Crewe, it was used on most Rolls-Royce and Bentley automobiles in the four decades after its introduction and is still used in the Bentley Mulsanne.

History

Rolls-Royce premiered the world's second V8 engine in 1905 for their Rolls-Royce V-8 Legalimit - governed not to exceed the legal speed limit in Britain at the time of 20 mph (32 km/h). It was not a success, with only three made and just one sold, which was soon returned to the factory to be scrapped. It was another decade before Cadillac pioneered a mass production V8-engined automobile.

Rolls-Royce acquired Bentley in 1931 and continued to use Bentley engines alongside their own for a time, although none was a V8. Prior to World War 2, Rolls-Royce had developed a 7.3-litre V-12 for the Phantom III, which was succeeded by the inlet-over-exhaust B60 straight-6 and B80 straight-8 series of engines. The B80 powered the Phantom IV limousine, whilst the 4.3-litre B60 was used until 1955 to power the Rolls-Royce Silver Wraith and Silver Dawn and the Bentley Mark VI. The B60's bore was enlarged in 1955, increasing the displacement to 4.9 litres, that engine being known as the B61.

The need for a new engine was recognised by Rolls Royce in the early 1950s and its development began in 1952, bearing no relation to the 1905 Rolls-Royce V8. The result was a series of V8 engines known as the L series, more specifically the "L410" for its bore size of 4.10 inches (104 mm), in keeping with company practice.

Developments of the L410 continued in production powering Rolls-Royces up to 1998 and Bentleys into the 21st century. Bentley, under Volkswagen ownership since 1998, continues to develop the L410 for its range of cars. Roll-Royce ceased using the L410 with the switch to BMW ownership of that brand in March 1998 and introduction of a BMW sourced V12 engine in the Rolls Royce Silver Seraph.

Since 1998 therefore, development and use of the L410 engine can be said to have been exclusively a Bentley enterprise.

L Series engine nomenclature

The factory nomenclature for the L Series V8 engines, in chronological order, is as follows:

• L3801950s 5,204cc initial development version
• L4101959 6,230cc production version powering Phantom and S Series
• L4251965 7,439cc experimental version
• L410B1965 6,230cc updated production version powering Silver Shadow and T Series
• L4101970 6,750cc production version, capacity increase achieved by 'stroking' to 3.90 inches (99 mm)
• L410E1970s 7,269cc development version with 4.20-inch (107 mm) stroke
• L3801970s 5,352cc "Thermodynamically Optimised Porsche (TOP)" experimental version
• L410D1982 6,750cc turbocharged production version installed in Bentley Mulsanne
• L410I1986 6,750cc fuel injected version
• L410IT1987 6,750cc fuel injected production version in Bentley Mulsanne Turbo
• L410ITI1991 6,750cc fuel injected, turbo, intercooled production version of Bentley Turbo R & S and Continental R & S
• L410MT1997 6,750cc low pressure turbo
• L410MT/S1997 6,750cc turbo
• L6751998 6,750cc development name for Arnage version of the turbo, later reverted to "L410"
• L410TT2007 6,750cc production version introducing twin MHI turbochargers with intercooler
• L410HT2009 6,750cc variable cam phasing "high-torque" production version for 2009 Mulsanne

Main engine capacities

6.25-Litre

The engine was of an overhead valve (OHV) design, angled at 90 degrees, and featured a central camshaft and wedge-shaped combustion chambers. As initially released, the bore x stroke was 104.14 by 91.44 millimetres (4.10 in × 3.60 in) and displaced 6,230 cubic centimetres (380.2 cu in), which is rounded up to describe it as the six and a quarter litre engine.

When new, the Rolls-Royce/Bentley V8 was rumoured to be an American engine design licence-built, but it was developed in-house by Rolls-Royce and Bentley engineers. This can be seen in its design characteristics, with features like an aluminium alloy cylinder block with wet liners, gear-driven camshaft, (initially) outboard spark plugs and porting inspired by the Rolls-Royce Merlin aircraft engine. The bore spacing of 4.75" was unlike any American V8 engine and the firing order was 1-5-4-8-6-3-7-2 something uncommon in any period American OHV V8. The deep skirted crankcase design is also rare with American V8 engines. Rolls-Royce however did use General Motors transmissions in their vehicles, notably the Hydramatic in Silver Cloud and the Turbo-Hydramatic in the Silver Shadow.

Models

• Rolls-Royce Silver Cloud II and III(1959–1966)
• Rolls-Royce Phantom V(1959–1968)
• Bentley S2(1959–1962)
• Bentley S3(1962–1965)
• Rolls-Royce Silver Shadow(1965–1970)
• Bentley T-series(1965–1980)
• Rolls-Royce Phantom VI(1968–1982)

Production

• Rolls-Royce Limited(1959–1973)
• Bentley, subsidiary thereof
• Rolls-Royce Motors(1973–1982), subsidiary of Vickers plc (from 1980)
• Bentley, subsidiary thereof

6.75-Litre

Starting in 1968 for the 1971 model year, the stroke of the V8 engine was increased from 3.6 inches (91 mm) to 3.9 inches (99 mm), thereby increasing the engine capacity to 6,752 cc (412 cu in). Known as the Six and Three-Quarter Litre or simply the Six and Three-Quarter, it is the most widely used and well known of all the versions and possibly the most famous British V8 engine of all time, save for the Rover V8 engine.

Except for the Chevrolet Small-block V8, the Rolls-Royce/Bentley V8 is the longest-lived engine currently in production. From a standpoint of usage in currently sold vehicles, the L-series V8 engine is the longest-lived engine produced. Production of the Chevrolet small-block engine has been relegated to sale as a crate engine, and the replacement GM LS engine is dynamically unrelated to the classic Chevrolet V8 engine.

The power output of the 6.75-litre over the 6.25-litre version was not very significant at the outset, the emphasis being on increased torque. The plethora of revisions introduced throughout its life were primarily to comply with emissions; one of the most notable changes is the new firing order of 1-5-4-8-6-3-7-2 introduced in 1987. With improved tuning and the addition of turbochargers, the 6.75-litre became one of the world's most powerful automobile engines and enormously enhanced the image of Bentley as a sporting car maker.

The process of evolving the engine has been gradual and continuous; by 2006 almost all the 1959-specification engine components had been upgraded, so that the current twin-turbo 6.75-litre engine produces over 150% more motive power and torque than at the beginning of its life, has 40% better fuel economy, and produces 99.5% less exhaust emission. In the current Brooklands and Mulsanne, the 6.75-litre engine produces 395 kilowatts (537 PS; 530 bhp) and 1,050 newton metres (774 lbf⋅ft) of torque.

The 6¾ litre (512PS) engine used in Bentley Mulsanne was built at Crewe plant, and takes nearly 30 hours to build.

The twin-turbo V8 engine was reported to be phased out, although it continues to be cast by Grainger and Worrall in Bridgnorth, Shropshire, England and fully machined and partially assembled at the company's machining facility in Telford, Shropshire, England.

Models

• Rolls-Royce Phantom VI(1968–1991)
• Rolls-Royce Silver Shadow(1970–1980)
• Bentley T-series(1970–1980)
• Rolls-Royce Corniche(1971–1996)
• Rolls-Royce Camargue(1975–1986)
• Rolls-Royce Silver Spirit(1980–1998)
• Rolls-Royce Silver Spur/Flying Spur(1980–1998)
• Bentley Mulsanne(1980–1992)
• Bentley Eight(1984–1992)
• Bentley Turbo R, S(1985–1997)
• Bentley Azure(1995–2003, 2006–2009)
• Bentley Continental R, S(1991–2003)
• Bentley Brooklands(1992–1998)
• Bentley Turbo RT(1997–1998)
• Bentley Arnage(1998–2009)
• Rolls-Royce Corniche, Corniche S (2000)(2000–2002)
• Bentley Brooklands Coupé(2008–2011)
• Bentley Mulsanne (2010)(2010-)

Production

• Rolls-Royce Limited(1968–1973)
• Bentley, subsidiary thereof
• Rolls-Royce Motors(1973–2002), subsidiary of Vickers plc (1980–1998)
• Bentley, subsidiary thereof (until 1998)
• Bentley Motors Limited, subsidiary of Volkswagen Group(1998–present)

The marques' split

BMW began supplying Rolls-Royce and Bentley with engines in 1998, specifically a V12 engine for the Rolls-Royce Silver Seraph and a twin-turbo 4.4-litre V8 engine to replace the 6.75-litre for the Bentley Arnage. BMW V8 engines were used exclusively in the Arnage from 1998 to 2000.

BMW no longer owns the rights to produce any pre-2003 Rolls-Royce or Bentley engines. The current Rolls-Royce Phantom and its derivatives use a normally aspirated BMW V12 engine, which has no technical similarities with the L410 engine. The Rolls-Royce Ghost introduced in 2010 uses a 6.6-litre twin-turbo V12.

Under Volkswagen Group, the Bentley Arnage's BMW engine was phased out from 2000 to 2002 and the L410 engine was reintroduced in highly redeveloped form. The Arnage-derived Brooklands uses the most powerful version of the engine yet. Those models and the convertible Bentley Azure are produced alongside the Bentley Mulsanne and smaller Bentleys based on the Continental GT, which use the VAG W-12 engine.

Bentley Mulsanne Turbo Engine