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).
The development and performance of a new turbulent cylinder head and induction pipe drain for the large bore 20/25 model.
| Identifier | ExFiles\Box 103\4\ scan0141 | |
| Date | 22th January 1936 | |
| x519 To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}2/KW.22.1.36. Turbulent Head & Induction Pipe Drain - Large Bore 20/25. We are now in a position to release the induction pipe and cylinder head for the big bore 20/25. By this we mean that our preliminary running has not shown up any major faults. The characteristics of the new cylinder head are as follows - It gives considerably more top horse power than the non-turbulent type of head fitted to Sg{Arthur F. Sidgreaves - MD}'s and Wor{Arthur Wormald - General Works Manager}'s cars, but it is slightly down on low speed performance. Actually we consider that for a car of the 20/25 type the low speed performance is more important than the maximum speed, and we are carrying out tests to modify the power curves so that we can get the required result. With the head as it stands now, the big bore 20/25 has of course very much better low speed pick up than the present standard car. It is very difficult to get a good value for the idling on one car: at present it does not seem quite so good as the mock-up scheme but we think it is passable, and here again a little development work may make a big improvement. We are quite happy about the drain in the induction pipe being effective, and this pipe can now be released for production. We have got to make sure that the drain does not affect the starting. Without the drain we have proved that the starting of the big bore unit with the Stromberg carburetter is in no way inferior to the present standard carburetter. The carburetter air intake now requires completion, but this is a part which could be fitted when the cars are on test. | ||