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).
Engine modifications, balancing increased power with the undesirable engine roar from a double carburetter.
| Identifier | ExFiles\Box 19\1\ Scan134 | |
| Date | 2nd November 1931 | |
| X7120. Sg.{Arthur F. Sidgreaves - MD}1/WT2.11.31. S/W. Hs.{Lord Ernest Hives - Chair}...from Sg.{Arthur F. Sidgreaves - MD} Copy to Wor.{Arthur Wormald - General Works Manager} 27-EX. I spent some time on this car, with PN{Mr Northey}, and we formed the opinion that we should not be justified in taking advantage of the extra power and acceleration resulting from the combination of the modifications on this engine, in view of the definite sacrifice of an important Rolls-Royce feature, i.e. silence. We consider that even for a Continental type, the amount of roar would be highly undesirable. I need hardly say that this is extremely disappointing, so much depends upon being able to increase the difference between the Continental type and the standard as much as possible with the smallest amount of delay. I am aware that this engine has diamond-mounting, which appears to be very good and helpful, and also :- (a) W.W. camshaft. (b) High-compression head. (c) Double W.W. Carburetter. As apparently the excessive roar with full-throttle, especially at about 52 m.p.h. and 65 m.p.h. results primarily from this double carburetter, I am anxious to know whether we could grasp any important advantage by fitting the W.W. camshaft alone, that is with our standard carburetter as now available. The H.C. head is of course now standard for the Continental type and has shown a definite improvement on our trials car 31-GX, and it might be a help in certain cases (such as that of Fairey), if we could advantageously fit the W.W. camshaft also, or, is the view taken that with our standard carburetter there would be no gain, and that the diamond-mounting should inevitably accompany any marked increase in engine speed and power ? In view of this decision. What is the next action you propose to take ? Is it possible to forecast the length of time which may be taken before we are in a position to test a modified single carburetter in something like final form ? At the end of your memo Hs{Lord Ernest Hives - Chair}4/MJ27.10.31 you state - "We are going ahead to produce twin carburetters with the further modifications". | ||