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).
Outlining tests to investigate the causes of engine detonation in Bentley cars.
| Identifier | ExFiles\Box 82\4\ scan0200 | |
| Date | 13th December 1935 | |
| To Hs{Lord Ernest Hives - Chair}/FD.{Frank Dodd - Bodies} x200 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}28/KW.13.12.35. Bentley Detonation. Whilst we are on this question of detonation, we should like to get a fairly comprehensive summary of features which can affect it on our cars. We think obtaining ignition advance curves with the governor cut out is a good method of determining what effect any modification has on the car. By actual variation in timing we can of course detect the value of a bent governor spindle. We should, however, like to know if all cylinders detonate equally on the average car; i.e., cut each cylinder out in turn and see if any one is a particular culprit. Then again, we know that water temperature has a very marked effect on this phenomenon. We ought to get a figure for a very low water temperature and a very high one. We should consider that 90°C. would be a good figure for the top end. We should like a curve showing the difference between Ethyl and Shell No.1, and the ignition advance characteristic which can be tolerated before detonation is audible. We also know that tappet clearance makes quite a difference as it alters the effective duration of the camshaft. We should like to know whether the difference in detonation can be detected with the tappets set at .001" and .006". We have ordered a set of sodium cooled exhaust valves. We should like to know whether lubricating oil running down the valve guides makes detonation better or worse. By removing the grummit, it should be possible to produce fairly copious overoiling. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||