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).
Investigation into ignition suppressor units, their effect on engine performance, and related complaints of radio interference and spark plug fouling.
| Identifier | ExFiles\Box 63\3\ scan0036 | |
| Date | 22th June 1934 | |
| -2- Hs{Lord Ernest Hives - Chair}/Sut.B/SA.22.6.34. Cont'd.{John DeLooze - Company Secretary} With regard to (a) we obtained a quantity of the usual "suppressor" units and carried out a series of bench experiments to investigate what effects they had on ignition. These "suppressor" units are small cylinders of solid carbon having a resistance of 10,000 ohms. Their function is to damp out the high frequency oscillations in the ignition H.T. circuit, known as the capacity component of the ignition spark. They very slightly lower the available H.T. voltage but from tests conducted in the Laboratory apart from the elimination of the "capacity component" they do not otherwise interfere with the main energy output of the ignition circuit. We have fitted up 21.G.IV complete with suppressors to ascertain if our bench tests are confirmed by chassis test. As it has always been held by certain modern physicists that the capacity component is necessary for entirely satisfactory ignition of an explosive gas we shall observe the chassis tests with interest. Actually there are two schools of theory in this direction each held by equally competent scientists each claiming certain experimental proof for their theories, Professor Taylor Jones at Glasgow University and Professor Finch at University College, London. Following definite complaints received from customers of misfiring occurring due to radio sets being installed, we visited Cricklewood to investigate the complaints. It appears that there are a large number of our cars in service with radio installed which have given no ignition trouble whatsoever but several cars have come in with misfiring complaints which in almost every instance has been due to the plug points being fouled with carbon. Removing the suppressors has always cured the carboning up trouble. This points to the fact that reducing the intense portion of the spark by the introduction of the suppressor has resulted in the plug points running relatively cooler, and suggests that a slightly hotter running plug could be used in conjunction with a suppressor. It would also suggest that preignition could be reduced on a given plug by the fitting of a suppressor and we intend trying out this theory on a Bentley engine. | ||