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).
Letter discussing car performance issues and potential modifications for models 19-GIV and 18-GIV.
| Identifier | ExFiles\Box 6\7\ 07-page181 | |
| Date | 6th November 1931 | |
| G.W.Hancock from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hotel de France, Chateauroux, Indre, France. X5230 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}3/AM.6.11.31. x5340 Many thanks for your letter of the 13th inst. We are interested in your statement re the side steering tube fouling the shock absorber but are rather puzzled as to why it did not happen on 19-GIV. We are, however, measuring up this car at once. We are also interested in your remarks re diamond engine mounting, and of course this is almost inevitable with the present design of diamond engine mounting. In view of what you say, do you not think it would be advisable to retain the spring plates at the top of the engine feet as these help to centralise the engine and one cannot imagine them transmitting any booms. Possible you will try them out and let us have your impressions. After our trial on 18-GIV in London against one of their Trials cars, we were rather impressed with the poorness of the low speed performance on 18-GIV below 30 M.P.H. At the same time we were surprised by the complete absence of detonation and torque reaction. You will understand that this characteristic was expected to a certain extent owing to the new camshaft fitted which definitely lets the gas out at low speeds. However, we hoped that we had more or less restored this low speed deficiency by raising the compression ratio and for this reason we should like you to check over the ignition timing andmake sure that you will not gain anything by having it further advanced. Our own tests were done on Ticknall Hill and we did not appreciate any loss in performance when the ignition was set at 10° before top dead centre. Re exhaust systems. We have now carried out some tests on the bench and have found,to our surprise, that we cannot gain anything from the 2" manifold and the 2" downtake pipe. Actually, the combination which we found to be quite successful on 18-GIV - the 1¾" manifold, down take, small front expansion box, P.2. silencer and 1¾" fishtail pipe - gives the same power as the system you are at present running and was considered to be quite alright fromthe point of view of silence and tinniness when the front expansion box was lagged. For this reason we shall send out these parts as soon as we can. We shall be very interested to know what | ||