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).
Comparing the exhaust system efficiency and lap speeds of the Phantom III and Phantom II.
| Identifier | ExFiles\Box 91\1\ scan0256 | |
| Date | 25th April 1936 | |
| X300 To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}21/KW.25.4.36. Re Phantom III. Replying to Sg.{Arthur F. Sidgreaves - MD}3/E.20.4.36. There is no question of fitting a cut-out to the standard Ph.III. The figure was obtained to establish a value for the efficiency of the exhaust system. As will be seen from the figures given below, the Ph.III exhaust system is much more efficient than the Ph.II; it only drops the speed 3 m.p.h. and incidentally is quieter. Cut-out closed. Cut-out open. Lap Speed. 22-EX (Ph.II). 83.7 M.P.H. 88.35 M.P.H. 36-EX (Ph.III). 87.38 M.P.H. 90.55 M.P.H. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||