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).
Improvements of a new engine head design over an obsolete one, focusing on self-ignition, silencer firing, and detonation.
| Identifier | ExFiles\Box 14\3\ Scan025 | |
| Date | 26th November 1928 | |
| - 2 - undoubtedly make the engine re-action vibrations more noticeable. R's car (14-EX) is actually running with 4.75 to 1 compression, and is giving quite good results. R.{Sir Henry Royce} is perfectly satisfied with it, but we are afraid Sales would object to the torque re-action vibrations. Whilst we have been able to use only a small increase in power we have made definite gains in other directions as follows :- a/- In the old design it was almost impossible to switch off after hard running without the engine continuing to run by self ignition, even although the throttle was partially closed. In the new design this self igniting of the charge is cut out, and it is possible under normal conditions to switch off without closing the throttle entirely, and therefore it is also possible to start off the switch under certain conditions now, whereas it was impossible with the old design of head. b/- The new head almost entirely eliminates the firing of charges in the silencer when running down hill, this is the result of the new head firing weak charges regularly and efficiently, and thereby burning the charge in the engine instead of in the silencer. c/- Detonation is eliminated as the result of the improved form of combustion chamber, and the better disposition of the plugs made possible by the new head. This means we can with the new head run for much longer periods before decarbonisation becomes necessary than was possible with the obsolete design. From the foregoing it will therefore be seen that whilst we have not been able to take advantage of the main increase in power available by the use of higher compression, we have undoubtedly made a real advance, and the improved design has well justified its adoption. BY BY.{R.W. Bailey - Chief Engineer} | ||