The Pioneer of V8 Bentleys -- 1960 Bentley S2 Saloon HISTORY

The Pioneer of V8 Bentleys -- 1960 Bentley S2 Saloon HISTORY


1960 Bentley S2 Saloon HISTORY
The Pioneer of V8 Bentleys

The S2 debuted as the forerunner of the V8 engine that still exists today. Here, we will follow the history of the S-type series in detail from its birth to its ending.

text:Hiromi TAKEDA
Translation: Mako Ayabe and Michael Balderi

A Hidden Gem

At the Paris Salon in autumn 2008, Bentley unveiled the Arnage Final Series, a limited production run of just 150 units. Since its debut in 1998 as the flagship of the Bentley saloon range, the Arnage has remained at the top of the ultra-luxury market. The Arnage is the final chapter in its history and is a model with top-of-the-range tailoring appropriate for this closing chapter. However, this ultimate model, which will be officially launched in 2009, marks the end of the Arnage line-up and the 50th anniversary of the traditional V8 engine, which has long been the power source of every Bentley model.
The V8 engine in the current Arnage T and Arnage Final Series uses the latest turbo technology to produce 507 hp/4200 rpm and 102 kg-m/3200 rpm of torque. In addition, the series' most powerful coupe, the Brooklands, delivers a maximum output of 537 hp and a maximum torque of 107 kg-m. However, this V8 engine was originally created 50 years ago, in 1959, as the power behind the Cloud II/S2. Bentley has a history of placing little emphasis on the presence of power sources, so the V8 remains a hidden gem.

Bentley x 8-cylinder

Bentley, a partner of Rolls-Royce since 1931, launched the Bentley Mark VI and its development, the R-Type, in 1946 as the first post-WWII model and the first model with an all-steel standard body, adapted to the post-war economic climate, mainly in the USA. As a model, it was a hit, with total production far exceeding 7,000 units. However, the Mark VI series was originally based on the pre-war design and layout with thorough refinements. It nonetheless appeared old-fashioned by the sensible standards of the mid-1950s. For R-R/Bentley, which at the time was under strict orders to corner the foreign market as the 'spearhead' of the British export industry, the introduction of a new model with an 8-cylinder unit and a modern body to suit North American market needs was a veritable challenge. The company's very survival depended on it. Thus, in the spring of 1955, the sister car, R-R Silver Cloud/Bentley S-Type, which was also a great success, made its debut with a 4887 cc in-line 6-cylinder F-head power unit. The unit for the final R-Type Saloon/R-Type Continental was therefore retained. This was a desperate measure, as a new 8-cylinder engine could not be developed in time. The project that would later become the R-R Silver Cloud/Bentley S was initially developed under the internal code ‘Bentley 8’ (or VIII), and initially the project was seriously discussed to be powered by the same B80 5665 cc in-line 8-cylinder unit as the R-R Phantom IV. The engine originated from three military engines developed by Rolls-Royce in 1938, just before the Second World War. These were the in-line 4-cylinder 2.8-litre B40, the 6-cylinder 4.5-litre B60 and the 8-cylinder B80. Known as the B-range engines, they were of so-called ‘modular design’, with all three sharing the same bore x stroke (88.8 x 113.4 mm), indicating the fact that they all shared the same components. The design was modular, with components shared by all three models. The cylinder head was an F-head with OHV intake and side-valve exhaust. Of the three B-range engines, the R-R technicians considered the B60 engine to be the basic form of power from the postwar Mark VI to the forthcoming new S-Type. At the same time, as mentioned above, plans were underway to use the B80 engine as the power source for Bentley passenger cars. The 'Silver Ripple' project was expected to be the new top-of-the-range model for the Bentley brand in the new post-war R-R/Bentley launch. They were to build only one prototype with a B80 in-line 8-cylinder during World War II, purely as an experimental vehicle. This was the 'Scalded Cat', which deployed a pre-war Bentley Mark V chassis. The Scalded Cat, as the name implies, showed off its intensely dynamic performance, tearing along like a wild feline. However, the prototype's handling never reached the level required by Bentley. The power generated by the B80 engine completely exceeded the potential of the old Mark V chassis, and the excessive engine weight and long block straight-8 layout, originally intended for large military vehicles, had a negative effect on the drive.
The company also considered converting the car to an aluminium block for use in passenger cars. This, though, was deemed impossible in keeping the mechanical noise within Bentley's standards, and the idea was abandoned. The ‘Scalded Cat’ and the 'Silver Ripple' project were never put into series production, and were unfortunately put on hold indefinitely.
Meanwhile, the Bentley 8 project also sought to develop a new V12 engine, which already had a solid track record in the R-R Phantom III and aircraft engines. But the lessons learned from the terrible handling of the Scalded Cat led to the early demise of the possibility of a huge 12-cylinder engine, and the project was swiftly abandoned. Taking into account the popularity of V8s in the North American market, the decision was then made to develop a lighter and more modern V8 engine for use in the new model.
The Bentley 8 project was thus incorporated into an official new model project of the R-R Company, based on the premise that it would be equipped with a completely new V8 design. Development proceeded at a rapid pace under the direction of W.A. Robotham, who became the company's design and development manager after the war. However, the development of this V8 unit was not completed in time for the Silver Cloud/S-type to go into production.

The S-Type with the L410 Unit

Four years after their debut, in the spring of 1959, the Silver Cloud/S-Type evolved into the Silver Cloud II and S2, respectively, with the long-awaited V8 unit. For the Silver Cloud series, this heralded the long-awaited arrival of a real hit.
The new V8 unit was later given the codename ‘L410’ and would undergo various improvements to extend its life into the 21st century. The design is said to have been initiated by engineer Harry Grylls, who became head of the development team at Rolls-Royce during the development of the Silver Cloud/S-Type after W.A. Robotham retired in 1955.
Grylls was originally an engineer who had spent his career in the aero engine department of R-R. This is perhaps why the new V8 unit was made entirely of aluminium, drawing on aircraft reciprocating engine technology.
When development of the new V8 unit began, the displacement was set at 5.2 litres, which was not much different from the final B60 6-cylinder F-head (4.9 litres). Still, in response to the power/torque shortage and in consideration of future development potential, the displacement was increased by approximately 1 litre to 6230 cc. The bank angle was a conventional 90° for a V8. The head was a push-rod OHV, abandoning the F-heads that had been central to the standard post-war R-R/Bentley design.
The bore and stroke ratio was 104.1 x 91.44 mm, making it the first ever oversquare R-R/Bentley passenger car engine. Furthermore, the hydraulic tappets, first introduced in the early V12 for the R-R Phantom III before World War II, but abandoned in the later models due to lack of technological maturity, were also revived for the first time in almost 20 years.
Despite having two more cylinders and a significantly larger displacement due to the aluminium head and block, the new 6.2-litre V8 OHV unit was only slightly lighter than the conventional in-line 4.9-litre 6-cylinder F-head unit. Nevertheless, it remained a super heavyweight, with a total weight of more than 400 kg. Twin SU 13/4-inch carburettors were fitted and, in keeping with R-R tradition, the power specs were undisclosed. The sole catchphrase was ‘sufficient for your needs’, but the specialist magazines of the day estimated that it was slightly over 200 HP.
In addition, the traditional Bentley four-speed manual transmission was dropped in favour of a column-shift Hydra-Matic four-speed AT only. And in combination with the new V8 engine, the top speed was increased from 106 mph in the Cloud I/S-type era with the conventional 6-cylinder to 113 mph. Acceleration times were also improved from 18.8 to 18.2 seconds in the SS1/4 mile (0-400 m).
Interestingly, the changes to the exterior throughout the vehicle’s evolution to the Silver Cloud/S2 were almost negligible, in contrast to the evolution of its mechanics. The few exceptions included slight changes to the design of the air intakes on either side of the radiator grille and the emblem, which was mounted on the boot lid. There are, however, more than a few changes hidden under the engine hood.
First of all, the layout of the engine compartment was significantly changed to match the shape of the V8 engine, which was shorter in length but altogether wider. The transmission was also advanced slightly. In addition, the ventilation system was equipped to incorporate a cooling system which facilitated air conditioning, equipment first adopted as optional on the Silver Cloud/S-type. Finally, power steering was fitted as standard on all models.
Thus, the S2, the definitive Bentley S-Type, was well received by the market, especially in North America, thanks in part to the excellence of its V8 engine. By the time it evolved into the Bentley S3 in October 1962, 1,863 units of standard saloon SWB versions (15 of which were Drophead Coup? by H.J. Mulliner) had left the Crewe factory. A further 57 units of LWB versions (six of which were special bodies) were to be built at the Park Ward factory.
After the transformation of the standard steel saloon into the S-Type, the sporty model that embodied Bentley’s glory was launched in the spring of 1955, coinciding with the launch of the standard S-Type and forming the next generation’s natural inheritance. This was the famous S-Type Continental, but that is another story for another time.