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).
Summary comparing single and double exhaust manifolds, detailing power loss, temperature, and noise issues.
| Identifier | ExFiles\Box 66\2\ scan0303 | |
| Date | 26th November 1927 guessed | |
| contd :- -3- was necessary in order to avoid interference from cyls. where the exhaust periods overlapped. It will be remembered a number of indicator diagrams were taken shewing the effect of over-lapping and various manifolds were tested with the result that we were led to abandon the original Phantom single exhaust manifold in favour of the present standard. It was found however that if the single manifold and exhaust piping were made very large the power losses could be fairly small but even then not such good results could be obtained as with double manifolds. SUMMARY. (1) The single manifold exhaust system Lec.2432/677 gives greater power loss than the present std. system. The complete system loses approximately 20 HP. at 2500 r.p.m. The present std. looses 8 HP. (2) The loss is in the manifold. Part of the loss can be avoided by taking the exhaust from cyls. Nos. 5 and 6 and leading it into the general stream in the down pipe. See sketch V.182. We have previously had evidence that an opposing flow of exhaust gas reduces the power output. (3) The air gets hotter round the single manifold - approx. 23°C hotter. (4) The system is definitely more noisy to the passen-gers in the car than std. system. It emits a metallic noise. We propose trying the new scheme of exhaust heating for the hot spot in conjunction with the present exhaust system. Hs{Lord Ernest Hives - Chair}/A.C.Lovesey. | ||