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Bentley 4 Litre and 4 Litre Supercharged (1926 -1930)


 

If it hadn't been for the fact that the Bentley 3 Litre showed little potential for a further increase in performance and the Bentley 6 1/2 Litre was prone to consume tyres at an alarming rate there might never have been a Bentley 4 1/2 Litre. Around the end of 1927 series production started of the new model with an engine designed to the proven pattern of the Litre. Collecting victory after victory on various race tracks the Bentley 4 1/2 Litre became highly successful. Based on the 4 1/2 Litre the sensational 'Blower' Bentley was created. A Roots-type supercharger by Amherst Villiers gave 9 1/2 lbs boost at 3,500 rpm. To run a Bentley 4 1/2 Litre Supercharged in Le Mans a minimum of 50 cars had to be produced for homologation purposes. Though the engine had been extensively modified lubrication was poor and cooling problems were immense. At Le Mans never and rarely ever in another major race Blower Bentleys finished first.

No. made:

665 Bentley 1/2 Litre (including 6 cars, which were built after the take-over by Rolls-Royce)


55


Bentley 4 1/2 Litre Supercharged (including cars, which were built solely for competition)
 
4.5 litre supercharged
Wheelbase 3302 mm 130 in  
Track front 1422 mm 56 in  
rear 1422 mm 56 in  
Length 4597 mm 181 in  
Width 1740 mm 68.5 in  
Kerb weight 1727 kg 3807 lb  
Type S-4
SOHC
8 valves total
2 valves per cylinder
Bore stroke 100.00mm 140.00mm
3.94 in 5.51 in
Bore/Stroke ratio 0.71
Displacement 4398 cc
(268.382 cu in)
Unitary capacity 1099.5 cc/cylinder
Compression ratio 5.10:1
Fuel system 2 SU carbs
Aspiration S/Charged
Max. output 177.4 PS (175.0 bhp) (130.5 kW)
@3500 rpm
Coolant Water
Specific output 39.8 bhp/litre
0.65 bhp/cu in
0-50mph (80 km/h) 10.00s
Top speed 166 km/h
Power-to-weight 101.33 bhp/ton
chassis
Engine location Front
Engine alignment Longitudinal
Drive RWD
Top gear ratio 1.00