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).
Test report on the performance of experimental cars, identifying reasons for inferior speed and the effects of bonnet ventilation.
| Identifier | ExFiles\Box 24\5\ Scan235 | |
| Date | 25th June 1930 | |
| -5- might be worth certification by the track authorities for sales propaganda. We traced the inferior performance of 18-EX to a tighter engine by allowing the cars to come to a standstill from 60 M.P.H. in top gear. 19-EX car ran 125 yds. further than 18-EX during this test. We attribute the slow speed of the American car to - (a) No cut-out. (b) Air cleaner. (c) P.l. camshaft and cylinder head and timing for best low speed acceleration. (d) No ventilation of bonnet. (e) Small wheels and consequently low gear ratio. The American car kept commendably cool, top water temperature 85°C. atmospheric temperature 19°C. but we could not do many tests as their cylinder head cracked after a few laps. The speed M.P.H. reading was on the whole on the low side once the scuttle had become warmed up. The air valve became unscrewed on 19-EX. This is a trouble that we invariably experience when we do any prolonged speed bursts and might give the impression of petrol shortage to the un-initiated. It was noticeable that the ventilated bonnet improved the high speed performance. Without ventilation the maximum speed of the car is not maintained for more than one lap. Fan effect at High Speed. We took a link out of the fan belt before starting | ||