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).
Comparison of induction systems and the effect of different tyre sizes on vehicle performance.
| Identifier | ExFiles\Box 124\2\ scan0168 | |
| Date | 14th May 1940 | |
| -2- Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}6/JMo.14-5-40. Comparison of 3.S.U. and dual Stromberg induction systems on 11.B.5 is shewn in columns A.{Mr Adams} and B. As borne out on the road there is no difference in acceleration up to 60 m.p.h. and very little from 60 to 80 m.p.h. Maximum speed is only increased 2 m.p.h. by the 3.S.U. sustem. Column E.{Mr Elliott - Chief Engineer} shews performance of 4.B.50 in its present condition, i.e., fitted with 7 x 16 tyres. The very small difference in direct gear and overdrive top speeds is a fair indication that the car is geared too high. Column D.{John DeLooze - Company Secretary} shews the effect of fitting 6.50 x 16 rear tyres. Acceleration figures are now as good as on 11.B.5. up to 70 m.p.h., and overdrive top speed remains practically unchanged. In answer to the criticism that the car would now become undertyred, we would point out that the extra speed of 11.B.5. causes three times more H.P. loss than the extra weight of 4.B.50. Hence, the tyres on 11.B.5. still appear to have a bigger job of work to do, and there does not seem to be any reason why smaller rear tyres should not be used to advantage. Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} | ||