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).
Report page detailing experiments and blueprints for modifying induction pipes and carburettors to reduce engine roar.
| Identifier | ExFiles\Box 179\2\ img049 | |
| Date | 12th December 1931 | |
| -3- Ha/Rm.{William Robotham - Chief Engineer}1/WJ.12.12.31.Cont'd.{John DeLooze - Company Secretary} (Sketch (3)) [Blueprint Sketch 3 Text] 2.450 1.750 .500 DIA 1.875 1.875 BORE TWO 1.875 THROTTLE S.U'S PIPE. NON RAMMING. ③ [Typed Text] The induction pipes were then joined together in the centre for the full bore. The metering and slow running of the carburetters was upset by this alteration as one would expect, but the roar completely disappeared. Experiments with the size of balance hole showed that with a hole 1.125" dia. the roar only came on with the last half inch of accelerator depression, whilst with a hole 1.250" dia. the roar was entirely absent. A confirmatory test was next tried with the R.R. twin carb. by putting a distance piece between the carb. and the induction pipe face through which was drilled a hole having an area of 1.625 sq. ins., i.e. bigger than that necessary on the S.U. The result was disappointing, the reduction in roar only being about 20%. (Sketch (4)) HS{Lord Ernest Hives - Chair} 492 [Blueprint Sketch 4 Text] SKETCH 4 .200CRS. 5.750 SWAGE ENDS .200 1.250 O/D x 16 S.W.G S/D TUBING PIPE CUT THUS EACH END & WELDED UP WITH ADAPTER AFTER FITTING WITH CONNECTING TUBE | ||