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 on self-ignition in Phantom engines after switching off.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan214 | |
| Date | 8th June 1926 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair}/ACL. c.c. to BJ. RG.{Mr Rowledge} c.c. to E.{Mr Elliott - Chief Engineer} SA. c.c. to EY. Wor.{Arthur Wormald - General Works Manager} c.c. to CY. ORIGINAL SELF IGNITION AFTER SWITCHING OFF ON PHANTOM ENGINES. X699 X8230 We have carried out some tests in order to find out something about the phenomenon of self ignition with the ignition switched off which frequently occurs on these engines after a hard run. When running with open exhausts it was observed that self ignition would not take place unless the exhaust valves had reached at least a slight red heat and then would not occur immediately on switching off, but only after the engine revs. had fallen. This is characteristic of the trouble on the cars and it is only just before the engine stops that it gives one or two convulsions. The influence of speed was further demonstrated by the following experiment :- Three ignitions only were switched off when the valves reached a red heat and the engine was motored over by the remaining three cylinders. If the resulting motoring speed was above 1750 r.p.m. self ignition on the three 'switched off' cylinders would not occur although the valves remained red for an appreciable time. If however the motoring speed was only about 1000 r.p.m. self ignition readily occurred until the valves cooled. Furthermore it was found that if the valves were only at a dull red heat, self ignition would not take place at a speed above contd:- | ||