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).
Merits and technical details of increasing the engine size of the 25HP model.
| Identifier | WestWitteringFiles\V\October1930-February1931\ Scan176 | |
| Date | 27th December 1930 | |
| SG.{Arthur F. Sidgreaves - MD} FROM R.{Sir Henry Royce} (At Le CanadelHenry Royce's French residence.) C. to Lord Wargrave. C. to LHS.{Lord Herbert Scott} WOR.{Arthur Wormald - General Works Manager} C. to Mr. Claremont C. to HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} DA{Bernard Day - Chassis Design} CONFIDENTIAL. ORIGINAL re. 25HP. My dear SG.{Arthur F. Sidgreaves - MD}, Your memo. re. increasing the size of the 25HP. came to hand on the 26th. Derby have been pressing for this but I rather understood Sales did not wish to take it out of its class - i.e. 20/25HP. I felt that the small increase in stroke that we had arranged was about the best, and rather feared, if greatly increased, that we should be - (1) Making it definitely compete with the 45HP. (2) Needing a new chassis, back axle, clutch, and in fact, everything. History generally has been that everyone makes a big or little model and gradually enlarges it until they ultimately start a new and smaller one to fill its original place. Therefore my own feeling was rather to reduce the size of the 45HP. which requires more room than one now finds in London. (P. 2. is actually much easier to handle than the Silver Ghost or P. 1.) But London conditions are not very suitable for big vehicles except in the main thoroughfares. It is possible that some increase in the 25HP. is the only way to make it compete, because apparently we cannot sell it except with bodies that ought to go on the 45HP. chassis. I therefore agreed to a small increase, and telegraphed the same day: "SUGGEST KEEPING EXACTLY TO DRAWINGS ALREADY MADE FOR "JAPAN BUT INCREASING SCALE FIVE PER CENT WHICH WILL "GIVE US 3.4 BORE X 5.25 STROKE AND CAPACITY OF 4.7 "LITRES WITH TAX AND HP. RATING OF 28." This is all that is asked for but slightly different proportions as we have struggled with the design to get some of the features and proportions exactly as we think best. E.{Mr Elliott - Chief Engineer} will adjust the sizes exactly: my figures are approximately right but I suggest we should keep within the £28. tax. I would not go to £29. because it might be thought like 3/11. and not 4/-. (1) | ||