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).
Report page detailing tests on engine efficiency, ignition timing, and the effects of a cooled exhaust valve on detonation.
| Identifier | WestWitteringFiles\P\October1926-November1926\ Scan015 | |
| Date | 18th September 1925 guessed | |
| contd :- -5- The brake efficiency naturally falls as the load is reduced, due to the friction and pumping losses assuming a relatively greater proportion to the power developed, but it will be seen that dual synchronised ignition gives no greater efficiency than the single ignition and at small loads is virtually just as 'late' as if one ignition were employed. Another curve shews how the efficiency is slightly increased by adjusting the ignition for each load. We have here proved that so far we have been unable to appreciate any difference between the two ignitions with regard to the efficiency of throttled charges. EFFECT OF COOLED EXHAUST VALVE ON DETONATION. A test was made with only one cylinder running in which the exhaust valve was cooled by means of a spray of water directed on to it from a pipe inserted into the port. Although the valve was cooled sufficiently to prevent firing after switching off the ignition, detonation was still evident when running and only very slightly less severe than when not cooled. GENERAL OBSERVATIONS. We have not experienced any mechanical trouble or observed any piston knocks. The distribution is fairly good with the standard exhaust hot spot and we consider it is better than on the standard Phantom. SUMMARY. The general conclusions we have arrived at from these preliminary tests are :- contd :- | ||