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).
Design of a Straight '8' engine for the Wraith chassis, evaluating the suitability of a centrifugal blower.
| Identifier | ExFiles\Box 6\6\ 06-page016 | |
| Date | 21th July 1934 | |
| SECRET. To Sg.{Arthur F. Sidgreaves - MD} and Wep. from K.{Mr Kilner} c. Hs.{Lord Ernest Hives - Chair} Hy.{Tom Haldenby - Plant Engineer} Ex. R.R. Straight '8' - Wraith Chassis. We have been pushing on well with the Wraith chassis, and we shall be able to show on Tuesday next a preliminary general arrangement of the chassis and body work to give some idea of its general proportions relative to the SpectreCodename for Phantom III and other cars. The general design as regards the engine on which we have been working is based on our present technique very largely, that is, it has an overhead valve engine with a turbulent head of the Bentley type. We carried out an investigation to see what it would mean to fit a centrifugal blower to this engine, and we find it is not possible to make a satisfactory job as owing to the use of overhead valves the blower and carburetter are pushed right up and crowded against the top of the bonnet. We think as we said at the last meeting in Derby, we have got to consider this and having done so our conclusion is that the blower is not suitable for this type of engine. The result moreover would be very little better if any at all than the Graham Paige as regards performance, and we should get nothing for the increased complication of the overhead valve engine. We have therefore been considering what design of engine would give us a better result both normally aspirated and blown, and at the same time a convenient arrangement of auxiliaries which would allow of the conversion to the blower with the minimum of alteration. The two valve ramp head does not appear to lend itself well, so far as we can see, to an arrangement of this sort, and it is not at the moment giving us sufficient improvement over our normal Bentley head to justify very serious consideration. The head we have in mind is the so called high power head which was fitted to the 4 litre Bentley that was | ||