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).
Comparison of ignition characteristics and throttle design between the Silver Ghost and Phantom models.
| Identifier | ExFiles\Box 1\3\ B001_X 93-page82 | |
| Date | 7th October 1926 guessed | |
| -2- Contd. We are now assuming that ignition of small charges is completed in the cylinder on the Silver Ghost but in the case of the Phantom ignition commences in the cylinder and is completed in the silencer. Conversely it may be assumed that when explosions do not occur in the silencer (i.e. in the case of the Silver Ghost) ignition does not take place at all and that the explosion in the silencer is the first attempt at ignition of small charges. Under this assumption the Phantom engine has a better capacity for igniting small charges than the Silver Ghost. Apart from this the Silver Ghost is more immune from explosions for other reasons. The piston throttle gives decidedly more definite closing than the Phantom butterfly type throttle. After the throttle, on a Silver Ghost, cuts off the induction pipe port to the carburetter, there is a further .250" piston throttle movement before its movement is arrested. This ensures a definitely closing throttle and reduces the possibility of explosions caused by coasting with the throttle slightly open due to the weight of the driver's foot on the accelerator pedal. Again, the ratio of accelerator pedal movement to throttle opening is lower on a Phantom than on a Silver Ghost. This produces a less selective accelerator pedal operation on the Silver Ghost which again reduces the possibility of keeping the throttle from closing by the weight of the foot. Contd. | ||