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).
Test report on Bentley cars at Brooklands track, investigating the effects of axle ratios, wings, and exhaust systems on performance.
| Identifier | ExFiles\Box 155\1\ scan0096 | |
| Date | 23th June 1933 | |
| X788 To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. EV.{Ivan Evernden - coachwork} Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}1/KT. 23.6.33. BENTLEY - TESTS ON BROOKLANDS TRACK. Axle Ratio. We have carried out tests on Brooklands using 2.B.IV. and 3.B.IV. to establish a value for the effect on maximum speed of 5% variation in rear axle ratio; the top gear ratios being 4.1 and 3.909:1. Both cars were tested with each rear axle ratio and in neither case was the maximum lap speed affected by the change in top gear ratio. The actual figures obtained are as follows, all test being with cut-out open :- | Top Gear Ratio | Lap Speed MPH | | |---|---|---| | | 2.B.IV. | 3.B.IV. | | 3.909:1 | 83.84 | 86.32 | | 4.1 : 1 | 83.5 | 86.32 | Wings. The effect of the mudwings on 2.B.IV. was investigated, the front wings (flared type) account for 4.07 m.p.h. and the complete set of wings reduce the maximum speed by 5.62 m.p.h. | | All Wings. On. | Front Wings. Off. | No Wings. | |---|---|---|---| | Lap Speed MPH | 83.0 | 87.07 | 88.62 | Exhaust. The exhaust systems on these two cars are the same as will be fitted to the first fifteen production chassis. The cut-out (Lec.3441/3453) has already been turned down because it does not make sufficient noise. By reason of the small power loss in the complete exhaust system it was not expected that much increase could be obtained by opening the cut-out. | ||