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 characteristics and axle ratios of the Big Bore Bentley.
| Identifier | ExFiles\Box 82\4\ scan0230 | |
| Date | 21th January 1936 | |
| W/S - Cx.{Major Len W. Cox - Advertising Manager} L20D Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KW.21.1.36. Big Bore Bentley. Replying to Cx.{Major Len W. Cox - Advertising Manager}10/KW.17.1.36. There is no doubt that the big bore Bentley can do 100 M.P.H. To do this it requires an 11/43 axle ratio. The standard ratio will be the same as for the old car, 10/41, and with this ratio a true road speed of 96 M.P.H. represents 4,500 revs., which is the maximum engine speed and cannot be exceeded. Therefore you cannot claim increased M.P.H. for the standard big bore. We agree that the 10/41 axle gives by far the best results for English conditions, where acceleration is so much more important than maximum speed. In the case of enthusiasts, however, you can point out that if a higher axle ratio is fitted the big bore engine can get a certain amount of advantage from it at the higher speeds; in fact, 100 M.P.H. can be exceeded under favourable conditions. It should be observed that the cut-out has now been omitted, which is worth perhaps 1 1/2 M.P.H., should a car be bought on a maximum speed stipulation. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||