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).
Letter to the S.U. Company regarding petrol pump starvation issues and performance on the Phantom III.
| Identifier | ExFiles\Box 149\1\ scan0232 | |
| Date | 16th April 1936 | |
| X1263 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}1/RW. 16th April, 1936. The S.U. Company Ltd., East Works, Adderley Park, BIRMINGHAM 8. Dear Sirs, We have recently had trouble with starvation at high speeds on the Phantom III, and in conjunction with tests on the carburetter we have also taken flows from the S.U. petrol pump as supplied for this type of car. The actual free flow taken on several pumps of this type comes out reasonably consistent and ranging from 225-250 pts/hr. We were surprised to find, however, that the maximum pressure the pump would register, that is, no delivery, was 2" Hg. or approx. 1 lb/sq.in., as we understood that this pressure should be 2 lbs/sq.in. Attached herewith is a curve showing the flow relative to restriction in the delivery line, both with the standard pump having a maximum pressure of 1 lb/sq.in., and a pump fitted with springs as supplied by you of .068" dia and having a maximum pressure of 1 1/2 lbs/sq.in. It will be seen that the delivery in the case of the standard pump begins to fall off with the slightest restriction, as per the filter and needle orifice etc., whereas the stronger 1 1/2 lbs/sq.in. pump does not fall off rapidly until there is a back pressure amounting to 3/4 lb/sq.in. The latter pump failed to operate on one side after several hours and we should like further information on the characteristics of the pump; i.e., whether we have misunderstood the maximum pressure figure and its controlling factors. | ||