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).
The development and testing of semi-expanding carburettors for the Peregrine engine, comparing them with S.U. carburettors.
| Identifier | ExFiles\Box 1\10\ B001_X106 TO X 110-page104 | |
| Date | 26th March 1933 | |
| γ 108. To Sg.{Arthur F. Sidgreaves - MD} From Hs{Lord Ernest Hives - Chair}/Ra. c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. Hy.{Tom Haldenby - Plant Engineer} Da.{Bernard Day - Chassis Design} c. Hdy.{William Hardy} EV.{Ivan Evernden - coachwork} Hs{Lord Ernest Hives - Chair}/Ra.1/KT. 26.3.33. PEREGRINE CARBURETTERS. We have done a great deal of work on the semi-expanding R.R. carburetter on Peregrine. Two different types of the semi-expanding carburetter have been built, and some half dozen induction pipes have been made and tested in conjunction with them. Additionally, several hot spot schemes have been tested, both water and exhaust heated. The two most successful arrangements of the carburetter are shown in sketches V.1575 and V.1576 attached, the general arrangement of the large carburetter being to Lec.3325, the small one to Lec.3157. These two carburetters were compared with two S.U. carburetters arranged similarly to those on the R.E. Bentley. No particular trouble was taken with the distribution or the hot spotting of the S.U. carburetters. The results of the tests are shown on curves Rm.{William Robotham - Chief Engineer}Pr.42/43/44. Briefly, the small R.R. carburetter gave a consumption nearly as good as the S.U's, but the performance was noticeably inferior. When arranged for good consumption moreover, the carburetter was very susceptible to a flat spot on the pick up, even with maximum hot spotting. The large Rolls-Royce carburetter gave a top speed performance equal to the S.U.'s but definitely inferior acceleration over the intermediate speeds and a 10% worse petrol consumption. The difference in acceleration is equivalent to about four or five car lengths between 10 and 50 m.p.h. The difficulty in getting a good petrol consumption on the semi-expanding carburetter seems to be connected with accelerating, as at constant speeds on the test bed this unsatisfactory feature is not so marked. There is no doubt that on this particular engine the two S.U. carburetters at present give the best results; we agree that S.U. slow running is not as consistent as the throttle edge. | ||