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).
Exhaust system tests focusing on various configurations to reduce noise and improve performance.
| Identifier | ExFiles\Box 6\7\ 07-page184 | |
| Date | 8th November 1931 guessed | |
| (2) (4) 2" manifold. P.II. Front Expansion Box. 2" intermediate pipe. P.II. Rear Silencer. 1 1/2" diam. Fishtail pipe. Results are:- Tinniness as before. A bad silencer period at 28-35 M.P.H. on the pick up but otherwise remarkably good. (5) As (4) but Front Fishtail Pipe, Expansion Box and Intermediate pipe Results are:- Tinniness very much better when ticking over on the pick up. Booms reduced. Silencer period still bad at 30 M.P.H. This is the state in which the car left for France. All these tests were repeated with a 1 1/2" manifold, downtake and intermediate pipe, which in our opinion improved the system for silence and with a biggest expansion box, the biggest silencer and intermediate pipe was considered quite possible. [handwritten note in margin: front-] We are now going over the systems on a bench test to find out which is the best for power output. We are also working on the P.II. to see why we cannot get away from the lagging which is found necessary and which is so unsatisfactory from the life of the hot pipe. Our experience so far, is that if we put the thickness of the pipe up to 2 1/2 we could do without the lagging but this adds so considerably to the weight of the exhaust system that we are trying to find a way round it. We are carrying on with these experiments in the hope of being able to provide some information which will be of some assistance on J.III. and the new P.II. systems which we believe you have at present under consideration. | ||