On-road testing of Bentley’s Speed Six Continuation Series cars is now underway, following the completion of the final Blower Continuation Series customer car. The OEM decided to create 12 replicas of the 4.5-liter supercharged ‘Blower’ and the 6.5-liter Speed Six – both of which are historic racing cars.
In period, the two cars raced as friendly rivals; the supercharged 4.5-liter ‘Blowers’ were prepared and entered by the Hon Sir ‘Tim’ Birkin’s private team, while the Speed Six was Bentley’s winning works entry in Le Mans in 1929 and 1930. Today, the build and preparation of both cars come under one roof in the Mulliner workshops, Bentley’s bespoke and coachbuilding division.
With all customer Blowers now complete and delivered, Mulliner’s focus turns to its second continuation project. The first two cars – Car Zero and Factory Works – will undergo months of static and dynamic analysis.
In 2020, a project team of Bentley Mulliner engineers, craftspeople and technicians worked closely with notable UK-based specialists and suppliers to create the world’s first pre-war continuation series. According to the OEM, development took tens of thousands of hours – and the Continuation Series models exactly replicate the originals from 1930, apart for minor items that were changed to avoid illegality.
The continuation projects are said to have triggered the relearning of lost skills within Bentley. Technicians and artisans, young and old, are now equipped with the knowledge and experience needed to build and maintain pre-war Bentleys.
The Continuation Blower has passed a rigorous inspection program to qualify for an Historic Technical Passport, making it eligible to compete at FIA-sanctioned events for historic vehicles.
For Speed Six, two original Speed Sixes were used as a master model: the company’s own Speed Six, GU409, and ‘Old Number 3’, a works Speed Six, which was driven in the 1930 Le Mans 24 Hour race. The latter was loaned by its owner to provide the Mulliner team with data on dimensions, materials and components, down to the last screw, nut and bolt.
The Mulliner Classic team has also received help from the W.O. Bentley Memorial Foundation, which provided 80% of the original drawings and notes used. The Continuation cars will include modifications that were made by the Bentley works team to improve reliability and performance in the 1929 and 1930 Le Mans races; the works Speed Sixes won both races by a distance.
Over 600 individual new parts including a new engine block casting were fabricated for the new 6.5-liter race spec engine, which in period developed 200bhp. Initial dyno testing has shown the Continuation Series engines to develop 205bhp; higher outputs would be achievable with the aid of modern engineering materials (as many classic racing teams do) but the aim of the Continuation Series team is to create a Bentley exactly as it would have looked and performed in 1930.
Following its reveal at the 2023 Goodwood Festival of Speed, Speed Six Car Zero has been undergoing durability evaluation. By the end of this phase, it will have covered the equivalent of 35,000km of real-world driving through 8,000km of track driving. Intervals of gradually increasing duration and speed are designed to check functionality and durability under the most challenging conditions.
