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).
Comparative horsepower curve graph for the Silver Ghost and Phantom models.
| Identifier | ExFiles\Box 5a\5\ 05-page201 | |
| Date | 8th August 1928 guessed | |
| B.H.P. 110 100 90 80 70 60 50 40 30 20 500 1000 1500 2000 R.P.M. PHANTOM SILVER GHOST FLYWHEEL H.P. C.O. OPEN. COMPARATIVE HORSE POWER CURVES. SILVER GHOST & PHANTOM | ||