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).
Notes on engine power increase, supercharger performance, and noise reduction.
| Identifier | ExFiles\Box 173\3\ img039 | |
| Date | 4th April 1934 guessed | |
| Owing to the fact that the II boost pressure obtained is only light up to 2000 R.P.M. it has not been found necessary to change the engine compression ratio which remains at 6.72-1. The power of the engine, which is side valve 265 cu. ins displacement, has been raised from 92 H.P. at 3300 R.P.M. to 132 H.P. at 4000 R.P.M. Other points discussed were. Silence. What was greatest difficulty encountered? The supercharger runs at 5.76 engine speed and is driven off the 1.5 engine speed shaft by a single reduction worm. Their greatest difficulty has been in getting the drive quiet. The slightest inaccuracy causes noise. They have made an appreciable improvement by increasing the flexibility of the couplings. They were afraid of noisy ball races and so used plain bearings. They have tried different rotor forms and some have been noisy but never approaching the noise of a constant displacement blower. They find that the blower | ||