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).
The value of bonnet ventilation for radiator cooling efficiency, with test data from a Silver Ghost.
| Identifier | ExFiles\Box 178\1\ img032 | |
| Date | 15th February 1926 guessed | |
| - 16 - (d) Ventilation value. It is clear that as the cooling capacity of a radiator depends upon the air velocity through the core, it is essential for maximum efficiency that once air has passed through the radiator of a car it should have, as far as possible, unrestricted egress from the bonnet. The following figures, taken from our own tests on a Silver Ghost, confirm the value of ventilation. They indicate the lowest atmospheric temperature at which the car can be made to boil under the conditions of ventilation indicated. It will be noticed that though the road speed is only 30 m.p.h. the air temperature at which the car will boil is raised by no less than 14½° by removing the sides of the bonnet. This is due to the fact that a very large relatively high speed fan is fitted. [Chart Data] ATS TEMP ABOVE WHICH CAR WILL BOIL 18.2°C - No VENTILATION. 24.5°C - SHUTTERS OPEN .4" x 10.5" 32.7°C - BONNET SIDES OFF. CAR SPEED 30 M.P.H. FULL THROTTLE CONDITIONS. With increasing speed the value of ventilation becomes more marked. Thus large shutters which made 8° difference at 30 m.p.h. affected 11° improvement at 40 m.p.m. in certain tests which we carried out. contd. | ||