Engine for the first car in the series Bentley The Mulliner Blower Continuation was first launched on a specially prepared test bed at Bentley's Crewe.
The Blower Continuation Series is a series of 12 newly built re-creations of one of the most famous Bentleys of all time, the supercharged 4½-liter "Blower" created for racing by Sir Tim Birkin in the late 1920s. These 12 vehicles, making up the world's first pre-war sequel series, have been pre-sold to collectors and Bentley enthusiasts around the world.
When the engineering prototype of the project - Car Zero - was already under development, the first engine was recreated by Bentley Mulliner with expert support from specialists. While the engine was being built, a team of Bentley engineers began work on preparing one of four engine development test beds at Bentley's headquarters in Crewe to receive the engine. The engine test bed has been at Bentley since the plant was built in 1938, and the chambers were originally used to run in and power out the Merlin V12 aircraft engines produced by the plant for the WWII Spitfire and Hurricane fighters.
Test bed preparation involved making a replica of the blower front chassis to mount the engine, which could then be mounted on a computer controlled engine dyno. A new version of engine measurement and control software was written and tested, allowing Bentley engineers to monitor and run the engine to precise parameters. Because the Blower transmission differs significantly in size and shape from modern-day Bentley engines, a number of original Merlin test benches, which are still kept at Bentley, were used to adapt the test bench to fit these special engines.
When the engine was fully installed, the first start happened two weeks ago, and the first engine is now going through a certain break-in schedule before being tested at full power. The engines will be tested over a 20-hour cycle, gradually increasing both engine speed and load conditions from idle to 3500 rpm. After each engine has been fully run in, a full load power curve will be measured.
With the test bed up and running, the next step for the Car Zero engine is real reliability. When the vehicle is complete, it will initiate a track test program - running sessions of progressively increasing duration and speed, testing functionality and reliability in more challenging conditions. The test program is designed to achieve the equivalent of 35 kilometers of real travel on 000 kilometers of track driving and simulates famous rallies such as Beijing-Paris and Mille Miglia.
4½ liter supercharged engine
The newly created Blower engines are replicas of the engines that powered Tim Birkin's four Team Blowers raced in the late 1920s, including the use of magnesium in the crankcase.
The Blower engine began life as a naturally aspirated 4½ liter engine developed by V.O. Bentley. Like the 3-liter Bentley before it, the 4½-liter combined the latest technology from the individual engines of the day - single overhead camshaft, twin-spark ignition, four valves per cylinder and of course the now legendary aluminum Bentley pistons. The racing version of the 4½-liter WO engine made roughly 130 hp, but Sir Tim Birkin's Bentley Boy wanted more. WO has always focused on reliability and sophistication rather than absolute power, so his decision to find more power has always been to increase engine power. Birkin had a different plan - he wanted to recharge the 4½, and this idea, according to WO, "spoiled" his design.
With the financial backing of his wealthy financier Dorothy Paget and the technical skills of Clive Gallop, Birkin commissioned Supercharger Specialist Amherst Villiers to build a 4½ supercharger. A Roots type supercharger - colloquially known as a supercharger - was installed in front of the engine and radiator and was driven directly from the crankshaft. Internal engine modifications included a new, stronger crankshaft, reinforced connecting rods, and a modified oil system.
In racing style, the new 4½-liter supercharged Birkin engine was powerful - producing around 240 hp. Thus, the Blower Bentleys were extremely fast, but as predicted by the WO, also somewhat fragile. The Blowers played a role in Bentley history, including helping to secure the supercharged victory of the Bentley Speed Six at Le Mans in 1930, but the 12 races in which the Blowers competed were never secured.