Experiments to develop a new, quieter, and more efficient exhaust system for the Wraith III car to reduce BHP loss.
| Identifier | ExFiles\Box 8\8\ 08-page58 | |
| Date | 18th June 1938 | |
| b 23 To By. {R.W. Bailey - Chief Engineer} from Rm {William Robotham - Chief Engineer} /Wym. {G. Harold Whyman - Experimental Manager} c. to Hs. {Lord Ernest Hives - Chair} c. to Da. {Bernard Day - Chassis Design} c. to Mx. {John H Maddocks - Chief Proving Officer} c. to RHC. {R. H. Coverley - Production Engineer} c. to Da {Bernard Day - Chassis Design} /MGS. Rm {William Robotham - Chief Engineer} /Wym. {G. Harold Whyman - Experimental Manager} 12/JH.18.6.38. WRAITH III EXHAUST SYSTEM. We have been carrying out experiments on the exhaust system of the Wraith car, with a view to reducing the BHP. loss to a more reasonable figure, and also dispensing with the front expansion box, which has been a bugbear to us for a long time, in design, durability and cost. We have succeeded in developing a system, whereby we throw away the front expansion box and run a 2.00" dia. pipe direct from the manifold to the centre silencer, which has been altered in accordance with the attached sketch Rm. {William Robotham - Chief Engineer} 552 (this is a scheme of 3 way tuning with perforated pipes), retaining the rear silencer in its present form and fitting a 1.750" dia. tail pipe instead of the present 1.500" dia. pipe. This system is every bit as quiet as the present Wraith, and in addition to saving approx. 10 lbs. in weight, the BHP. loss at 3500 r.p.m. and 4000 r.p.m. is only 13.0 and 12.45 respectively, instead of 21.10 and 24.3 with the present system, a saving of 7.5 BHP. at 3500 r.p.m. and 11.85 BHP at 4000 r.p.m. An analysis of the BHP losses on the present exhaust system are herewith attached. We should now like design to draw out a proper scheme, so that we can get the system built up by the Works and also outside firms for cost analysis. We are at the moment experimenting with heavier gauge material for the downtake pipe, to try and dispense with lagging, and if successful, are hoping that with the reduced BHP. loss and consequent freer flow of the exhaust gases, we may be able to make this pipe in Mild Steel instead of Staybright. Rm {William Robotham - Chief Engineer} /Wym. {G. Harold Whyman - Experimental Manager} | ||
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).