From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Performance data tables comparing a standard 4 1/4 litre Bentley with a Vanvooren 'Aerodynamique' model with overdrive.
| Identifier | ExFiles\Box 161\1\ scan0064 | |
| Date | 1st December 1937 guessed | |
| -5- Standard 4 1/4 litre Bentley - axle 4.1 to 1, wheels 5.50 x 18 - Weight 33 cwts. in top gear. MPH. HP.due to const. T.R. HP.due to wind-age. HP. due to total resist-ance. HP.of car at road wheels. HP. avail-able for accel: Accel: ft.sec^2 in top gear. Time to get from 10 MPH. in top gear in secs. 10 1.32 .134 1.454 16.00 14.546 4.73 --- 20 2.64 1.075 3.715 32.50 28.78 4.68 3.12 30 3.96 3.63 7.59 50.00 42.41 4.60 6.29 40 5.28 8.60 13.88 65.00 51.12 4.17 9.62 50 6.60 16.80 23.40 78.00 54.60 3.56 13.39 60 7.92 28.00 35.92 86.00 50.08 2.72 18.05 70 9.22 46.00 55.22 89.75 34.53 1.61 24.83 80 10.54 68.70 79.24 89.75 10.51 .43 39.43 90 11.86 98.00 109.86 86.50 nil nil --- Vanvooren "Aerodynamique" standard 4 1/4 litre Engine, 4.1 to 1 axle 1.2 to 1 overdrive, changing up at 70 MPH - 5.50 x 18 wheels, weight 34 cwts. MPH. HP.due to const. T.R. HP.due to wind age. HP.due to toal resist: HP.of car at road wheels. Changing up at 70 HP. avail-able for accel: In top gear HP. available for accel: Accel: in top gear in ft.sec^2 Time to get from 10 MPH in top gear in secs. 10 1.36 0.49 1.409 16.00 14.591 14.591 4.61 --- 20 2.72 .397 3.117 32.50 29.383 29.383 4.63 3.18 30 4.08 1.34 5.42 50.00 44.58 44.58 4.70 6.33 40 5.44 3.18 8.62 65.50 56.88 56.88 4.50 9.51 50 6.80 6.22 13.02 78.00 64.98 64.98 4.10 12.92 60 8.16 10.72 18.88 86.00 67.02 67.02 3.53 16.98 70 9.52 17.05 26.57 85.00 59.43 64.18 2.80 21.62 80 10.88 25.40 36.28 88.50 52.22 53.47 2.11 27.58 90 12.24 36.20 48.44 90.00 41.56 -- -- -- 100 13.60 49.60 63.20 89.00 25.80 -- -- -- 110 14.96 60.00 74.96 84.00 9.04 -- -- -- | ||