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 Autovac vacuum feed system and its limitations on a Silver Ghost engine.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan240 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF Hs{Lord Ernest Hives - Chair}/AJL/LG3.12.25. VACUUM FEED. We have carried out a series of tests in which the old Silver Ghost pressure feed pump was used as a means of exhausting the Autovac tank. The limitations of the standard Autovac system are shown in Table 1. attached. It will be noticed that there are many running conditions under which the Autovac cannot supply [struck-through] sufficient petrol to meet the requirements of the engine; a similar set of figures for the New PhantomCodename for PHANTOM I, if the same tests were carried out on this engine, would show a greater number of conditions under which the Autovac will fail, owing to the greater amount of petrol consumed under full load conditions. Unfortunately, the Autovac system does not supply the greatest volume of petrol when it is needed, its action is entirely dependent upon induction pipe depression which is greatest when least petrol is consumed (under small throttle opening conditions) and least when most petrol is being consumed (full throttle con-ditions). Hence to function correctly it would be necessary for it to be able to supply a quantity of petrol very greatly in excess of that required at small throttle openings in order to supply sufficient at full throttle openings. Table 11. shows the results of tests carried out on a Silver Ghost engine, employing the petrol pressure feed pump as a means of exhausting the Autovac as an alternative to the induction pipe. In order to convert the pressure pump into a vacuum pump which would give reasonable results, contd:- | ||