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).
Blueprint graph comparing engine performance with different exhaust manifold and silencer setups.
| Identifier | ExFiles\Box 86\3\ scan0218 | |
| Date | 13th April 1938 | |
| -4- Rm{William Robotham - Chief Engineer}/D.Lee.1/MH.{M. Huckerby}13.4.38. B.23. OHC. VALVE TIMING 10.2°BT.{Capt. J. S. Burt - Engineer} E.O.43°B.B. D.{John DeLooze - Company Secretary} I.C.33°PB. E.C.12°P.T. L.B.8 PLUGS TAPPETS AT .006 ETHYL FUEL OPEN EXHAUST 4 PORT MANd+2 SILENCERS 3 PORT MANd+2 SILENCERS B.H.P. & M.E.P. M.E.P. B.H.P. 3 PORT To BENTLEY SILENCER TO BENTLEY SILENCER. R.P.M. With two silencers in parallel (Curve D), the 4 port manifold is better, the 3 port dropping 13 BHP, and the 4 port 11 BHP at 4000 r.p.m., and average drop of 8.06. The MEP being slightly up at the low speeds too, with the 4 port manifold. Continued. | ||