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).
Secret memorandum proposing engine and component upgrades for the 20HP model to increase performance.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan106 | |
| Date | 27th April 1929 | |
| E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} ) FROM R.{Sir Henry Royce} HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} ) (At Le CanadelHenry Royce's French residence.) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} PN.{Mr Northey} LHS{Lord Herbert Scott} ORIGINAL SECRET. R3/M27.4.29. REC'D AT WW. 29.4.29. 20HP. X5770 X5080 X5050 and 25.3HP. if bored 3.250. This will now become the 25HP. if bored 3.230". The new head (aluminium) has 1.35 valves instead of 1.25 (cast iron.) The throttle, uptake, induction passage, had already been made larger. The exhaust is more efficient and can easily be made more silent and like SS.{S. Smith} I do not propose that we wait for the new hypoid rear axle or the new front axle. My impression is that we should realise 20% to 25% increase over the present standard in average torque and maximum HP. CARBURETTER. This will need to be proportionately larger - i.e. about 25% increase in area of low speed and high speed venturi and extra air valve (over old pattern.) I believe we had a larger air valve which was not adopted. Longer inlet cams and rollerless tappets should be fitted if more power or speed will result. The gear has gone lower by the smaller wheels. This should not be reduced anymore or the engine will be over speed unless we get the valves to follow the cams up to 4000 revs., then I think we could reduce. CUTOUT. Perhaps this car would better please if it had a cutout always fitted. It is very good here when one wants to get over the ground quickly. ONE QUICK MOVE. My telegram suggests that all the moves for power (and the long frame for appearance) should be introduced at one time (1) For ease of management (confusion) of sales. (2) Instruction book and spares. (3) To make a definite impression of gain in performance. (4) To save time and money in testing and getting change completed. Shall still want the lighter bodies. While at Nice I saw Lady Boots car which had a broken 3rd. speed wheel. All I could see wrong was that the teeth were ground with sharp corners. [Drawing of a gear tooth profile] Sharp finish to grinding R.{Sir Henry Royce} | ||