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).
Technical comparison of the Grav-Vac and Autovac vacuum petrol feed systems.
| Identifier | WestWitteringFiles\Q\February1927-March1927\ 102 | |
| Date | 30th March 1927 | |
| To R: from Hs{Lord Ernest Hives - Chair}/AJL. c. to BJ. Wor.{Arthur Wormald - General Works Manager} ✓ c. to RG.{Mr Rowledge} ✓E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} EY. ✓ ORIGINAL EYRE AND ENGINE ROYCE Hs{Lord Ernest Hives - Chair}/AJL1/LG30.3.27. GRAV-VAC PETROL FEED. X3579 X3575 Attached are curves shewing the efficiency of the Grav-Vac vacuum petrol feed tank as compared with the Autovac. DETAILS The Grav-Vac tank delivers much less petrol at low induction pipe depressions than the Autovac under similar conditions, although it is more efficient at depressions in excess of 3.5" mercury. Owing to the failure of the Grav-Vac tank at low depression, exhaustive tests were not carried out. The Autovac system is deficient at low speeds full throttle, and any system which is less efficient under these conditions can be of no use to us. The Grav-Vac has all the known defects peculiar to vacuum feed systems; it is inefficient at low speeds and affects the slow running of an engine when idling. The apparatus is poorly made and is bulky. We have not been able to detect any point in which it is usefully superior to the Autovac System. Hs{Lord Ernest Hives - Chair}/A.J. Lidsey. G.I.A | ||