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).
Analysis of exhaust system losses on the big bore Bentley engine compared to the small bore.
| Identifier | ExFiles\Box 86\3\ scan0162 | |
| Date | 24th March 1936 | |
| X223 To E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}2/KW.24.3.36. Herewith an analysis of the present standard exhaust system losses on the big bore Bentley compared with losses on the small bore. Engine Unit | B.H.P. Developed at 3750 R.P.M. | Loss to complete Exhaust System 3.25 Bore | 110 H.P. | 14 HP. 12.7% 3.500 Bore | 131 H.P. | 18 HP. 13.7% Analysis of losses on present standard System at 3750 r.p.m. Big Bore Unit. Power developed at this speed 131 B.H.P. Item | B.H.P. Lost. Manifold | 3.5 Standard downtake pipe, front expansion box, inter. pipe and 1st silencer | 4.5 2nd intermediate pipe | 2.5 Standard rear silencer | 6.5 Tail pipe | 1.0 A larger manifold will enable us to fit a larger downtake pipe also. It is rather surprising that the standard exhaust system, when all the baffles are removed, loses 8 B.H.P. We have an experimental rear expansion box with a re-arrangement of baffles which saves 2 B.H.P. and is at present running 15,000 miles. The best we have been able to do with a straight-through system to rear box only is 19 1/2 B.H.P. loss. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||