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).
Investigation and potential solutions for vapour trouble on the 35-EX model.
| Identifier | ExFiles\Box 92\3\ scan0254 | |
| Date | 15th May 1937 | |
| To Sg.{Arthur F. Sidgreaves - MD} c. to Hs.{Lord Ernest Hives - Chair} 300-a Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}3/JH.15.5.37. 35-EX. We have confirmed the existance of vapour trouble on 35-EX which had been reported in France. With an air temperature of 20°C, the maximum speed of the car is reduced after a stop. The loss of speed and duration of the trouble being dependant upon the temperatures existing under the bonnet, along the petrol pipe and in the tank. The extra pump unit fitted did not as might be expected give any improvement whatsoever, but increased the noise when the pumps were dealing with vapour. The effect of temperature was investigated using only the single unit, when the maximum speed was brought down from 75 to 40 M.P.H. as the temperatures increased. 35-EX has no bonnet louvers but in view of the above results we are expecting to have complaints of vapour look in hot weather especially abroad. The only solution is the high pressure pump in the frame, but this requires further development and is not ready to be put into production. We are concentrating on it and will run the next 10,000 miles so fitted. A petrol pipe outside the frame was tried and an improvement obtained, but cooler conditions prevented us getting a true comparative value for it. This is also being fitted to the next 10,000 miles car, so as to be available for standardisation if required later on. Rm{William Robotham - Chief Engineer}/J.B.Dixon. | ||