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 of the 20/25 Autovac petrol supply system with a new horizontal carburetter.
| Identifier | ExFiles\Box 102\1\ scan0156 | |
| Date | 13th March 1934 | |
| X 5080 To SG.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to L. c. to Dy.{F R Danby} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}9/KN.{D. G. McKechnie - Sales}13.3.34. 20/25. Petrol Supply System (Autovac). Tests have been carried out to determine the efficiency of the standard 20/25 (Autovac) petrol supply system, when using the new Horizontal type Carburetter. As the Autovac relies solely on the depression in the Induction pipe for its working, a difference is bound to be shown when using the new horizontal carburetter, as against the standard 20/25 carb, owing to the difference in working depression. The attached curves show that below 2.0" Hg. depn. the engine consumption begins to exceed the autovac delivery, and at 1.5" Hg. depn., when the autovac ceases to operate, the engine is free to empty the autovac tank without any replenishment taking place. Above 2500 R.P.M. full throttle, the depn. has increased sufficiently to allow the autovac to maintain its full capacity, over and above the maximum demands from the engine. So, any amount of high speed work cannot empty the autovac on the road. But at lower speeds, where the depn. has fallen below 2.0" Hg; example - running at 30 M.P.H. full throttle on the road (top gear), the autovac will be empty in 11.5 minutes. It is considered therefore that the Autovac will be satisfactory with this Carburetter. Hs{Lord Ernest Hives - Chair}/C.T.Salt. | ||