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).
Table comparing car boiling temperatures at various speeds with different bonnet ventilation configurations.
| Identifier | ExFiles\Box 182\M19\ img174 | |
| Date | 16th May 1931 guessed | |
| Figures given are temps. at which car will boil if driven for sufficiently long at full throttle under the conditions named. C° | Type of Bonnet Ventilation | All Out | 45 M.P.H. | 30. M.P.H. | |-------------------------------------|---------|-----------|------------| | Vertical Louvres. | 44.5 | 37.5 | 36.5 | | Three ventilating shutters per side.| 41.5 | 33.0 | 32.5 | | No bonnet ventilation. | 38.0 | - | 27.5 | Tests on 19-EX. Had used small Hexagon U.S.A. Hexagon .305 across flats. 18 dents. Car weights 48 cwt. Centre 255 dia. round Radiator dimensions 29.9 X 35.7. Axle 11 X 41 Radiator shutters fitted for all tests. Louvred Bonnet F.7949/ Shutter Bonnet N.Sch.3232 | ||