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).
Graph comparing ignition advance curves for a standard Phantom engine and one with a turbulent head.
| Identifier | WestWitteringFiles\S\March1928-May1928\ Scan020 | |
| Date | 8th March 1928 guessed | |
| NECESSARY IGNITION ADVANCE FOR PHANTOM STD PHANTOM (SINGLE IGNITION) TURBULENT HEAD SINGLE IGNITION DUAL IGNITION ANGULAR DEGREES ADVANCE BEFORE T.D.C. 50° 40° 30° 20° 10° R.P.M. OF ENGINE. 500 1000 1500 2000 2500 3000 V268 | ||