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 with sketches detailing experiments on induction pipes and carburetors to reduce engine roar.
| Identifier | ExFiles\Box 13\3\ 03-page374 | |
| Date | 12th December 1931 | |
| -3- (Sketch (3)). 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 shewed 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 inductio 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)). Text from Sketch 3: 2.450 1.750 .500 DIA 1.2" 1.875 BORE TWO 1.875 THROTTLE SU'S PIPE. NON RAMMING Text from Sketch 4: SKETCH 4 .200CRS. 5.750 SWAGE ENDS .200 1.250 o/D x 16S.W.G S/D TUBING PIPE CUT THUS EACH END, & WELDED UP WITH ADAPTER AFTER FITTING WITH CONNECTING TUBE | ||