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 systems for in-line six-cylinder engines, comparing single and separate systems.
| Identifier | ExFiles\Box 86\3\ scan0214 | |
| Date | 9th April 1938 | |
| X 1171. 223 P By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} c. Sg.{Arthur F. Sidgreaves - MD} c. Da.{Bernard Day - Chassis Design} c. Lr.{Mr Ellor} c. Wd.{Mr Wood/Mr Whitehead} c. Da{Bernard Day - Chassis Design}/Jnr.{Charles L. Jenner} c. Rm{William Robotham - Chief Engineer}/SYM. Rm{William Robotham - Chief Engineer}5/R.9.4.38. EXHAUST SYSTEMS FOR BANKS OF 6 CYLINDERS IN LINE. The attached report confirms our previous experiments (Rm{William Robotham - Chief Engineer}/Ed{J. L. Edwards}6/Jm.{Mr Morley}5.11.37.) which clearly demonstrate that if six cylinders are run into a single exhaust pipe interference is likely to take place, and as much as 10% of the available horse-power can be lost in what would appear to be a very adequate size of exhaust pipe. With a bank of six cylinders divided into two separate blocks of three, each block having a separate exhaust system, a very high degree of silence can be obtained for a very small power loss. All our investigations have been carried out on naturally-aspirated engines, and supercharging may entirely alter the results. It would appear, however, that if for any reason a high degree of silence is required on an aircraft engine, the matter should be investigated on these lines. From the automobile point of view, it would appear that two separate exhaust systems can be made of more simple construction than a single system to do the same job, and, therefore, neither the cost nor the weight would be excessive. In consequence, we expect to swing over to the duplex system for our six-cylinder engines in due course. Provision for such a move has already been made by equipping the new engine which has just been designed with four exhaust ports, because with such an arrangement a neater lay-out can be obtained. Rm.{William Robotham - Chief Engineer} | ||