In the first entry at the 24 hr race the prototype of
the 4 1/2 litre won approval immediately.
It was tipped favourite to win, but had to retire early due to severe damage in the famous
White House accident.
Around the end of 1927 series
production of the 4 1/2 litre began and the
first cars were delivered that year.
The new model was manufactured in batches of 25 cars each,
modifications being incorporated at the
beginning of each series only. These were only minor changes, such as alteration to the radiator or the
use of better balanced crankshafts, because the fundamental construction of the 4 1/2 litre was
It was Woolf Barnato's financial
injection into Bentley that gave him a major
say in the company affairs
and one of the 'Bentley Boys', Tim Birkin, won him over to the idea of of achieving more output from
the 4 1/2 litre by fitting a supercharger and W O Bentley's opposition to the idea was overruled.
Within less than a year four 4 1/2 Bentley's were fitted with Roots twin-rotor superchargers.
A change in the cylinder block, crankshaft, pistons and gudgeon pins, and oil pump took place.
On the testbed an output of some
175 bhp was measured about 45 bhp more than the basic engine.
It was clear on the race track, however, after only a short time, that the extra power had been gained
only at the expense of reliability. Chiefly this was caused by lubrication and cooling problems which
often led to the breakdown of the Blower Bentleys. It became common place to see cars
retiring with damaged enginesafter having raced through a few laps in record time.
Sales of the 4 1/2 litre Blower
Bentley began in April 1930, at a time when the world economic
crisis had reached an ominous state.
During the years1936/7
(roughly ten years after 4 1/2 Bentley production had ceased) Rolls-Royce
built from remaining spare parts, taken over when Bentley was bought, six further 4 1/2 litre's.
These included the model's production run amounted to a figure of 665 cars. Of these the Blower
Bentley amounted to 55 cars, which figure includes the pre-production models built for racing purposes.