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 Jaguar and Vauxhall performance to inform specifications for a proposed 1.78 litre car, codenamed 'Myth'.
| Identifier | ExFiles\Box 148\2\ scan0231 | |
| Date | 16th August 1939 | |
| 2. Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork}9/N.16.8.39 Cont'd.{John DeLooze - Company Secretary} Chart Rm.{William Robotham - Chief Engineer}596 shews acceleration plotted against litres per ton mile. It will be seen that if all the engines had the same B.M.E.P. the acceleration would be directly proportional to the litres per ton mile and all cars would lie on the mean line. Consequently the distance above and below this line is an indication of the relative B.M.E.P's. Within the range in question fall the Jaguar 1.75 litre and the Vauxhall 14, two examples of different ways to the same end. The former a heavy car and the latter a light car, both having approximately equal axle ratios, and also equal acceleration over the chosen range. The chart illustrates the fact that the Jaguar therefore has a high B.M.E.P. to compensate for its heavy weight. The Vauxhall would appear to be the more reliable power unit, and the one which has room for development. Likewise we suggest that performance should not be achieved by a low gear, as this produces a fussy car. After studying these charts, and in the light of the above deductions we would suggest the following fundamental figures for the 1.78 litre car, the "Myth". Weight. - 23 cwts - very maximum 24 cwts. Wheelbase. - 9 feet 0 inches. Dimension 'E'. - 48 1/2" (as B.5). Axle Ratio. - 4.75 to 1, giving 4720 R.P.M. at 80 M.P.H. It has been suggested that we might gear for 5000 R.P.M. at 80 M.P.H. which is approx. 5 to 1. This we believe might be a too big reduction in view of our experience with Peregrine with 5.125 to 1. To sum up we suggest that we use the 14 H.P. Vauxhall as our model in preference to the Jaguar because the former represents the car of the future. Ev.{Ivan Evernden - coachwork} | ||