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 table of temperature readings at various positions on a Wraith cylinder head at full throttle.
| Identifier | ExFiles\Box 175\5\ img028 | |
| Date | 12th April 1938 guessed | |
| COMPARISON OF TEMPERATURE AT VARIOUS POSITIONS ON WRAITH CYLINDER HEAD. ALL TESTS AT FULL THROTTLE. R.P.M. | Temp. in outlet pipe from engine. | Temp. at proposed revised front position. | Temp. at rear position (original). 500 | 90 | 94 | 76 1,000 | 83 | 86 | 73 1,500 | 77 | 78 | 68. 2,000 | 74 | 75 | 66. 2,500 | 81 | 82 | 73 3,000 | 79 | 80 | 72. 3,500 | 84 | 85 | 77. 4,000 | 82 | 83 | 76. Rm{William Robotham - Chief Engineer}/Std. | ||