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).
The testing and development of an exhaust heated throttle and exhaust system components.
| Identifier | ExFiles\Box 81\2\ scan0169 | |
| Date | 7th October 1924 | |
| OyS-E-10724 -3- October 7, 1924. (4) Exhaust heated throttle. (cont'd). pipe was tried with verying amounts of "fishtail". The throttle acting as a silencer, it was found that even with a full bore outlet, the noise of the exhaust was inaudible in the car, and was a continuous hiss when listened to close. This scheme has been used to avoid the noise of the butterfly valve in the exhaust and the sticking of the butterfly by soot, which we experienced with the set sent over from England. The tests of the manifold with the free exhaust scheme as compared with the scheme using the butterfly in the exhaust tested on a standard car, are dealt with in attached report. The outlet from the throttle jacket is controlled manually by a butterfly valve to give seasonal adjustment only. This proposal of heating the throttle by a branch and waste pipe with seasonal adjustment has already been taken up with England. It was found that because of the water in the exhaust gases it is desirable to make the valve of a non-rusting material (stainless or high nickel steel). The looking nut of steel stuck on the threads, and was changed for a nickel silver nut which was satisfactory. A bronze or nickel silver nut would be used. Summarizing the report on the throttle tests it was found that the scheme used gave us adequate temperatures for quick starts in cold weather, avoided the collection of such fuel in the boilers, and did not reach the high temperatures sometimes obtained with the Derby bypass scheme. Avoiding any operating parts and the rattling and occasional sticking of the butterfly valve in the exhaust, is we believe a definite advantage. (5) Exhaust System. (See prints #5). Manifold. This is the system tested and approved in England of which drawings were brought over last April. The first manifold was made exactly to the dimensions of the drawings brought over. It was found however that the manifold grew bright red immediately on dynamometer test, and the engine lacked power as compared with standard engines of the same compression. Since we have ample room the manifold has been redrawn with a fifty per cent increase of cross section throughout as shown on drawings herewith. The new manifold is now on hand and will be tested for power and silence. Exhaust Boxes. The front exhaust box used was reduced in length to clear the steering, see print A-5634. The rear box was standard. The exhaust when idling was distinctly more audible than standard. | ||