Bentley’s Birkin Blower Goes Digital

Bentley’s Blower Continuation Series reaches an important milestone as the first CAD digital model that forms the blueprint for the classic race car recreation is completed by the Mulliner Classic team, working from their homes under UK lockdown.

Announced last year, the Blower Continuation Series is a run of 12 new Bentley Blowers, each of which will be an exact mechanical copy of the 1929 Team Blower built and raced by Sir Tim Birkin, and now likely the most valuable Bentley in the world.

The 12 new cars form the world’s first pre-war race car continuation series. The Bentley Blowers will be constructed using a combination of laser-scanning and precision measurement to create accurate models for the manufacture of new parts. 

The Continuation cars are being produced by a dedicated team in Bentley Mulliner’s Classic division, who are working with a team of vintage specialists to re-engineer and build the suite of parts needed to bring the new series of cars to life. 

In mid-April the Bentley Blower Continuation Series project celebrated the completion of the digital CAD (Computer Aided Design) model that will serve as the master design and engineering reference for the new cars. The engineers were able to complete the model while working remotely during the COVID-19 crisis. 

The digital design process has taken 1200 man-hours for two dedicated CAD engineers to complete the model from the scan data and measurements. The result is that an accurate and complete digital model for a 1920s Bentley now exists for the very first time.  

Bentley’s Team Blower has been carefully dismantled and then re-created in the digital world through a combination of precision laser-scanning and intricate hand measurement. The finished CAD model is comprised of 630 components across 70 assemblies. 

All 12 examples of the new (real life) classic cars have already been sold to keen collectors around the world. The first stages of build for the Bentley’s own engineering prototype – Car Zero – will begin in earnest soon. 

Apart from the process of assisting the development of parts design and development, the CAD model was also used to assist with the specification of individual customers’ cars, with Bentley’s Design team able to create accurate full-colour renders from the data. While the Continuation Series cars will be mechanically identical to the Team Blower, customers have been able to choose their own exterior and interior colours palettes and materials so that the cars are visually distinctive from their predecessor. 

The Bentley Blower Continuation Series cars replicate an example from the original ‘Team Blowers’ that were built for racing by Sir Tim Birkin in the late 1920s.  

All were campaigned on the racetracks of Europe, with the most famous car – Birkin’s own Team Car No. 2, registration UU 5872 – racing at Le Mans and playing a pivotal role in the factory Bentley Speed Six victory in 1930. It is this car, now Bentley’s own Team Blower (chassis number HB 3403) that is the master example for the Continuation Series.  

Using the original 1920s moulds and tooling jigs, and an array of traditional hand tools alongside the latest manufacturing technology, 12 sets of parts are being created, before Bentley Mulliner’s skilled heritage technicians assemble the new Blowers. 

Bentley’s original team car will then be reassembled, with the heritage team taking the opportunity to complete a detailed inspection with a sympathetic and conservative mechanical restoration where required to return the car to its original 1929 specification.  

As continuations of the original Team Blower, each of the new Continuation Series cars will feature four-cylinder, 16-valve engines with an aluminium crankcase with cast iron cylinder liners and non-detachable cast-iron cylinder head. The supercharger will be an exact replica of the Amherst Villiers Mk IV roots-type supercharger, helping the 4398cc engine to develop 179kW (240hp).  

The car’s structure will be a pressed steel frame, with half-elliptic leaf spring suspension with copies of Bentley & Draper dampers. Recreations of Bentley-Perrot 40cm mechanical drum brakes and worm and sector steering complete the chassis. 

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