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).
Experiments and suggestions for improving an SS engine's exhaust system.
| Identifier | WestWitteringFiles\T\January1929-February1929\ Scan027 | |
| Date | 21th January 1929 | |
| HS.{Lord Ernest Hives - Chair} BP. } FROM R DA.{Bernard Day - Chassis Design} DY.{F R Danby} } C. to BJ. WOR.{Arthur Wormald - General Works Manager} SG{Arthur F. Sidgreaves - MD} FN. ONB. O SECRET ORIGINAL SS.{S. Smith} ENGINE - EXHAUST HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} has temporarily made some of the experiments suggested towards more effectively quietening the exhaust, with the somewhat unexpected result that the engine feels smoother. I feel sure some of the vibration I can feel in 19-EX. (solid front feet) comes from movement of pipes in the exhaust system (cutout closed.) There is a lovely exhaust roar with the cutout open. This shakes the floor of the rear part of the car which one can feel by the feet through all the covering. This needs modifying but not spoiling. The beautifully regular burr at high speeds would please Summers, Cholmondeley, etc. The first part of this exhaust system seems quite good, but should be made of thicker pipe. I fear cast iron will not do, and that thicker steel will be found better. It might keep cooler if a little larger in the bore, and it might be bent out a little more as it is still some distance from the bonnet, especially at the rear. We ought to try a screen to keep the heat from the wires or the bonnet if found necessary, but this pipe does not seem hotter than usual for such pipes, especially considering the extra HP, but this you can compare on the dynamometer. Naturally it was a mistake to jacket it with asbestos: it was probably heated itself to orange colour. When HS.{Lord Ernest Hives - Chair} was here we studied the exhaust and thought we ought to break up the length into two somewhere near the middle, but perhaps not at the middle. A front silencer box does this, and the down pipe could slide into it as in Silver Ghost cars. Then also we thought that instead of bending the pipe in the plan we might try a side stepping box so as to avoid a straight through run which at present is from valves to cutout, and we imagined the hot gasses chasing up and down the pipe, piling up against the end like waves against rocky cliffs. Perhaps the perforations from the internal pipe into the silencer could be smaller. Naturally these would be just in front of the cutout, and we cannot suggest a better place, but some additional ones at the other end of the silencer might be tried. There are certainly periods that need damping, which seem easy if we can find some simple scheme or design. E.{Mr Elliott - Chief Engineer} and DA.{Bernard Day - Chassis Design} will also be working at this. R.{Sir Henry Royce} REC'D AT WW. 21. 1. 29. X7230 | ||