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 road test of a cast aluminium silencer system on car 20-EX.
| Identifier | ExFiles\Box 152\3\ scan0048 | |
| Date | 12th November 1929 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/AJL. c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} X442. X7230 X442. Hs{Lord Ernest Hives - Chair}/AJL1/BE12.11.29. CAST ALUMINIUM SILENCER - 'N' SCH: 2931-35 2947 The exhaust system with a cast aluminium front end and cut out valve and cast aluminium front expansion has been fitted to and road tested on 20-EX. Firstly, the silencer was tried alone, using a standard front expansion chamber. The silencing was found equal to the present standard system, only in one respect was it found to be definitely superior; when the cut out is open, hollow booms are considerably less pronounced, especially so on the over-run. The actual exhaust noise is not heard so much inside the car on forward, as when the standard system is employed. The exhaust cut out mechanism becomes stiff after running for some time in the open position, but has never actually seized up. It becomes perfectly free again when cold. The cast aluminium front expansion chamber was then fitted and the improvement previously found as regards hollow booming became less pronounced, presumably due to fitting a smaller down pipe. Apparently a change in size of pipe is good, but the same diameter throughout is bad. continued. | ||