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).
Dimensions and performance of a 25 HP exhaust system, particularly regarding silence and efficiency.
| Identifier | ExFiles\Box 86\3\ scan0001 | |
| Date | 1st December 1932 | |
| X223 To Ev.{Ivan Evernden - coachwork} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}2/ADL.12.32. With reference to your enquiry re Bensport exhaust system. Attached is a sketch of the dimensions we have been using on our 25 HP. exhaust system with the J.1 engine in it. Actually with the dimensions shown, our losses are not much more than 6% on 100 H.P. and if we had a slightly larger pipe from the exhaust pipe to the main silencer (which we should like to be 2.250" outside dia.) we think we shall be quite satisfied as regards efficiency. Concerning silence. Every time we alter the length of the exhaust system we have to make a new series of tuning tests. Generally speaking, if you could give us a chamber of 300 cu.in. capacity starting close to the front bend, and give us another chamber starting at the distance shown from the rear of the system having a considerably larger capacity, we think we shall be able to get a satisfactory job. We have shown a 1,000 cu.in. capacity for the rear one. Actually, the Bensport not having to cater for fishtail noise, we ought to be able to get away with 5 or 600 cu.in. capacity at this point. HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||