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).
Investigating exhaust noise on the 40/50 HP model.
| Identifier | ExFiles\Box 38\4\ Scan074 | |
| Date | 29th October 1924 | |
| R.R. 498A (20H) (D.A. 652 20-3-24) x.r.b. EXPERIMENTAL REPORT. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. BJ. c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} WOr.{Arthur Wormald - General Works Manager} c. to EP.{G. Eric Platford - Chief Quality Engineer} Expl. No. REF: Hs{Lord Ernest Hives - Chair}2/LG29.10.24. Handwritten: X3436 EXHAUST NOISE ON 40/50 HP. Handwritten: X3436 X3433 We have carried out experimental tests in connection with this and find that the noise which makes the exhaust note different to the standard 40/50 HP. comes from No.1. cylinder. We proved this by running the car on the road at a fixed speed cutting out each cylinder in turn. When we cut out No.1. cylinder we get rid of the objectionable noise. We have tried baffles in the front silencer. This made no improvement. We have tried carrying the exhaust in the centre of the front expansion chamber. This made no improvement. We have tried continuing the down pipe right down into the expansion box and stopping the end of the pipe and drilling holes through it. This did not get rid of the noise although it caused a considerable drop in horse power. We suggest now, that the noise is caused by the stream of exhaust which flows along the pipe from the five cylinders meeting the exhaust from No.1. cyl. Our reasons for thinking this is firstly because the tests show it is No.1. cyl. which is the cause of most of the noise, secondly, the EAC. engine on which all the exhaust ports are led into a branch and carried down the front of the engine, is free from this particular noise. At the present time we are modifying the contd :- | ||