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 ignition advance, overheating, petrol supply issues, and lap speed performance for cars 18-EX and 19-EX.
| Identifier | WestWitteringFiles\U\May1930-July1930\ Scan098 | |
| Date | 25th June 1931 | |
| -4- Ha/Bn.{W.O. Bentley / Mr Barrington}1/25.6.31.Contd. 20°C. As the ignition advance of the car is dependent on the relay which in turn is likely to lose efficiency if the oil viscosity is very low, these high oil temperatures seem dangerous from the point of view of causing retarded ignition and hence over-heating. It will be observed that the figures in graph (4) were taken with a ventilated undershield. Lap Speed of Cars. We had difficulty with the petrol supply of both 18-EX and 19-EX. After one lap full throttle the mixture weakened off, causing pre-ignition. We found that we could overcome this by running on "reserve" in the autovac. Presumably the pump does not quite keep pace with the engine requirements for sustained maximum speed. We were running at 3200 engine revs. We are confirming this trouble on the test bed. The maximum lap speeds recorded were :- 18-EX. C.O. Open. 79.5 M.P.H. 19-EX. C.O. Open. 84.5 M.P.H. American P.I. No cut-out. 71 M.P.H. We were astonished at the speed of 19-EX., which is a Cabriolet weighing 46 cwt. empty. We think its performance 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 | ||