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).
High-speed engine experiments, discussing performance, carburettors, component layout, and vibration mitigation.
| Identifier | ExFiles\Box 13\3\ 03-page322 | |
| Date | 28th May 1931 | |
| Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. Sg.{Arthur F. Sidgreaves - MD} c. WOr.{Arthur Wormald - General Works Manager} c. Ev.{Ivan Evernden - coachwork} X7080 R5/M28.5.31. HIGH SPEED EXPERIMENTS. X.7771 X.7080 X.7005. We are pleased to hear that you are getting on well with the power of P.2. at high speeds and maximum BHP. There is no doubt for maximum speed we must have the maximum BHP. available at full speed. We all realise that a late closing inlet is very desirable for high maximum HP. at high speed, and also makes possible a higher compression ratio and avoids detonations. This especially applies to the twin carburettors with their rather long (intermittent) induction passages. With the shorter passages and the two single carburettors we must expect that the inlet valve closing may be a little earlier, but not much. In this case the induction passages will also be more even in length. For practical reasons of safety and wet petrol we are not favouring the horizontal or down draught carburettors, but are endeavouring to get two separate vertical ones as high up, and as short as possible, but we are not making them ultra short as in some of the other models because we are hoping for better distribution in the arrangement that we are designing. It is the difficulty of accessibility of the ignition plugs that makes the down draught and horizontal carburettors much easier to apply. We have now made a good move by deleting the magneto and taking the water pump to the exhaust side, which gives more room for the carburettors and can make a better production design of the head as the induction pipe can be lower. Provided we can avoid detonations it would seem that the compression ratio might be raised somewhat when we fit the best of the engine mountings, namely the diamond type with soft rubber and torque reaction dampers. I believe that the chief source of vibration in the ordinary way is due to the vigour of the torque impulses, and this and the over-running vibration is the reason why I think we may get greater satisfaction from more cylinders, but I believe there is only one engine, namely, the 12 cyl. that will give us an alround definite improvement, and this is what we are trying to get. R.{Sir Henry Royce} | ||