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).
Bentley carburation, comparing different induction pipe designs and the effects of an intake silencer.
| Identifier | ExFiles\Box 31\5\ Scan051 | |
| Date | 2nd May 1933 | |
| To E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} X1487 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}6/KT.2.5.33. BENTLEY CARBURATION. XU53-3 INDUCTION PIPE. We hand you herewith preliminary figures comparing the round ended and square ended induction pipes and single and twin hot spots. The single and twin hot spots are not directly comparable because the single hot spot was used with the larger balance piece in the induction pipe. There is no doubt that it is most difficult to get any heat through the twin hot spot at low speeds without getting enough heat to spoil the distribution at high speeds. As a matter of fact we are at present trying a water heated hot spot on the road, which has proved successful on the test bed, and if it will function satisfactorily it will enable us to get rid of a number of parts. There is no doubt that the distribution of the square ended pipe is better than that of the round ended pipe, as will be seen from comparing curves 2 and 3. The power loss does not seem to be very large, but the difference in specific consumption is likely to be considerable. Therefore in view of the fact that there does not appear to be any difficulty in fitting the wiring controls with the square ended pipe, we recommend that we go for this. INTAKE SILENCER. With regard to the air intake silencer, the bend upsets the distribution slightly. We have an experimental bend which does not upset the distribution so much. We are trying to find out the exact difference which at present appears to be that the experimental bend is slightly larger than that of the proper design. The air silencer itself definitely restricts the intake and we are ascertaining by experiment the minimum dimensions necessary to silence the carburetters, and at the same time eliminate the loss of power. The specific consumptions on the bends, weakest maintained at 4000 r.p.m., are as follows :- | ||