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).
Phenomena observed when running a 12-cylinder car on only 6 cylinders, including comparisons to a Lincoln engine.
| Identifier | ExFiles\Box 4\1\ 01-page023 | |
| Date | 13th December 1933 | |
| To. Sg.{Arthur F. Sidgreaves - MD} / Rem.) from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} Hy.{Tom Haldenby - Plant Engineer} Bw. Hn{F. C. Honeyman - Retail orders}/Rm.{William Robotham - Chief Engineer} Running a 12 cylinder car on 6 cylinders. Referring to memo Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/Kr.12.12.33, the result of the above test is very gratifying and bears out the conclusions we have formed regarding these phenomena on a 12 cylinder engine. Until recently the Lincoln engine appears to have been fitted with a 4 bearing crankshaft, but the most modern type has a 7 bearing shaft which, as far as we know, has journals of 2.5 diameter, crankpins of 2.125 diameter and proportions generally showing that it is not ultra stiff. Bearing in mind that the engine is not particularly short and that the weight figures of the crankshaft indicate the presence of balance weights, we are strongly inclined to the opinion that the major critical on 6 cylinders is within the range of speed tested when running on second gear. As we have now on the SpectreCodename for Phantom III engine arranged to use two sparking plugs per cylinder always in operation and two 12 cylinder battery heads, there is not much likelihood of the engine being operated on 6 cylinders as this event would only occur with one ignition in operation and half of that wiped out by the failure of the one rocker arm or its points. Also believing as we do that such running would be as innocuous as the Lincoln test indicates, we feel completely satisfied on this point. E.{Mr Elliott - Chief Engineer} | ||