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).
Engine testing, discussing ignition sensitivity, detonation, compression ratios, and combustion head design.
| Identifier | ExFiles\Box 22\4\ Scan093 | |
| Date | 30th March 1927 guessed | |
| contd :- -7- flame travel from the points of propagation. We are not in possession of the corresponding ignition curves for the 20 HP. but are arranging to obtain these. The engine seems particularly sensetive to the ignition control, the power rising rapidly as the ignition is advanced to the values given on print 7. and falling rapidly when these values are exceeded. With one ignition appreciably more advance is necessary and the engine is slightly more prone to detonate at low speeds/when the two are employed. Slight audible detonations are evident up to about 1250 r.p.m. but considering the high compression ratio of 5.9 to 1 and the low grade fuel used for testing, the engine seems extremely good in this respect. Detonation was more severe on the 20 HP. when we tested it with a compression of 5.4 to 1. The combustion head has rather a peculiar shape, the only reason being apparently to accommodate the valves. The cyl. head is not detachable and it therefore becomes necessary in order to remove the inlet valve, to carry the guide in a form of cage which is removable. from the top permitting the valve to be threaded out through the cyl. bore. (See adjoining sketch). The cage is only held in position by the valve spring pressure. contd :- Text from blueprint sketch: INLET VALVE WITH DETACHABLE GUIDE CAGE THREAD FOR WITHDRAWING REMOVABLE CAGE HELD IN BY SPRINGS ONLY VALVE SEAT IN CYL. HEAD | ||