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).
Pros and cons of various engine configurations and future design directions using aluminium.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan279 | |
| Date | 24th June 1931 | |
| SG.{Arthur F. Sidgreaves - MD} FROM R.{Sir Henry Royce} C. to WDR. HS.{Lord Ernest Hives - Chair} C. to BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} re. ENGINE QUESTIONS I am very doubtful in connection with the 4.5 litre engine whether Sales will be satisfied with the 6 cyl. engine. We can see that the engine can be made smoother than the present 25HP. but it cannot approach the smoothness of the Buick 8 cyl. owing to the difficulties of keeping down the octaves and harmonics of the torsional vibrations, torque reactions, and over-run vibrations, these being natural to all 6 cyl. engines. It forces us to have rather a big flywheel or it produces certain vibrations in the transmission. It is however the least expensive we can hope to use, and its performance can be made probably better than the straight 8. for the cylinder capacity. I however should vote for the straight 8. if we could see how to get it supplied with gas, which is very difficult in its best form of 2 - 4 - 2. In the way it is used by Isotta (4 / 4) or with the zig-zag shaft in the case of the Bugatti, the problem of getting gas into the engine is alright, but both of these arrangements appear to have mechanical defects which would cause roughness. The broad Vee 8 cyl at 90° we cannot like in any of the forms in which we know it. The Lancia narrow 8.Vee might be a good engine but we do not know, so we finish up with our old friend and favourite, the 12 cyl. Vee at 60°, and if there is any doubt that J.{Mr Johnson W.M.} 3. will be satisfactory with a plain 6 cyl., after all the troubles we have lately gone through I should make an engine of over 4 litres capacity certainly 12 cyls. Regarding the design and method of construction for any future engines we have decided that the system of crankchamber and water jacket cast in one is preferable for saving work and weight. It is almost certain that the liner ought to be a loose one and as the weight of a motorcar of our class and size is of such great importance, and especially the weight on the steering wheels, we have decided that the whole of this unit of the engine should be cast in aluminium. Designs are proceeding on these lines. (1) | ||