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).
Comparative test results for various exhaust systems on the Phantom II engine.
| Identifier | ExFiles\Box 14\6\ Scan296 | |
| Date | 1st March 1934 guessed | |
| COPY. PHANTOM II EXHAUST TESTS. Comparative tests between several types of exhaust systems have been taken with regard to their respective power losses from the maximum open exhaust figure. These have been carried out on an 8-litre unit, with a standard 114º camshaft; large semi-expanding carb., and compression ratio of 5.2:1. The tests of the various complete systems are shown on the curve (Hs.{Lord Ernest Hives - Chair}1312), the summary of which can be taken as the figures obtained at 2750 R.P.M. the approximate speed of maximum power and as follows :- B.H.P. Power Loss. Back Press. In Manifold. Ins. Hg. (1) Open Exhaust (8.00 length pipes from each port). 179 - - (2) Large Resonant Silencer. Hs.{Lord Ernest Hives - Chair}789/90. 3" dia. Main Pipe. 156 23 10.0" (3) Vokes Silencer Complete. 146 33 17.5" (4) Present Production Anti-Crackle Silencer Complete. E.84643 with mods. LEC. 3759. 145 34 18.5" (5) Original Phantom II Exhaust System (Now obsolete). 136 43 26.0" The large resonant silencer, test (2), is the most efficient with regard to power loss, and it is upon this silencer that the chassis test are carrying out quietening tests, not by baffling the exhaust, but in a manner somewhat similar to that adopted in the development of the resonant air silencer. | ||