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).
Tests carried out on the boiling of petrol in pipes and pumps due to hot weather conditions.
| Identifier | ExFiles\Box 91\3\ scan0029 | |
| Date | 23th June 1936 | |
| 101 HOTEL DE FRANCE. CHATEAUROUX. Indre. France. GWH{George W. Hancock - Head Chateauroux}/HFW/S/JAB. 23rd. June 1936 To. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 2nd o to. [REDACTED] o to. [REDACTED] o to. [REDACTED] 32. EX. Tests carried out on boiling of petrol in pipes and petrol pumps. The weather has suddenly become very hot, the outside air temperature being 30°c. On occasions the car has become so hot that it is impossible to bear the hand on the wings or headlamps. We have therefore taken the opportunity to test the petrol system for vapour lock and boiling, and have effected cures where possible. The following tests were carried out with open bonnet louvers, as we had found it impossible to run the car at all with the louvers blocked by asbestos sheet. The troubles we are up against are in two categories. i.e. a) When the car is stationary b) When the car is running at speed. (a). During the run of 19.6.36, we drove 45 miles non-stop with an outside air temperature of 30°c, the under bonnet temperatures being never more than 62°c taken between the blocks. We then stopped for 15 minutes during which time, the under bonnet temperature rose to 70°c. By opening the throttle full, the engine was re-started without much difficulty, but the pumps were noticed to be ticking furiously. However, we continued our run, but only ran half a mile or less before the engine spluttered and stopped, the car having run until the petrol in the float chamber was exhausted. The pumps were working fast pumping no petrol at all; we verified this by removing the delivery pipe and no petrol came out. We therefore concluded that the pumps had during the halt, become hot and now failed to pump petrol owing to the vapour present. We waited for 25 minutes but they would not cool sufficiently to draw up petrol, so it was decided to pour water onto them. This was done, and immediately they became cool, petrol was pumped through. The test was repeated using the outside delivery pipe which you supplied us for our tests on Mount Ventoux. Again after waiting 15 minutes the car started and ran for about 500 yards and then stopped. The pumps remained clicking until we poured water onto them. We found on doing the same tests again, but waiting for a shorter period i.e. 7-10 minutes, that this did not happen, which goes to show that, although the under bonnet heat rose to 70°c the pumps take longer than this to get sufficiently hot to cause the petrol to vaporise. | ||