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 preliminary tests of a semi-expanding carburetter for the Peregrine engine.
| Identifier | ExFiles\Box 1\10\ B001_X106 TO X 110-page078 | |
| Date | 24th October 1932 | |
| X108. E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/LHS.{Lord Herbert Scott} c. to BY.{R.W. Bailey - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} Hs{Lord Ernest Hives - Chair}/LHS.{Lord Herbert Scott}9/KT.24.10.32. TEST OF SEMI EXPANDING CARBURETTER (Lec.3157) FOR PEREGRINE. We have carried out preliminary tests on the above carburetter, the comparative power output with the 1 5/8" bore single S.U. being shown on the Curve Rm.{William Robotham - Chief Engineer}Pr.31. At 4500 R.P.M. the power developed with the S.U. carburetter is 73.5 B.H.P. having an induction pipe depression of 1.6 ins. Hg. The semi-expanding carburetter develops 69.5 B.H.P. at the same speed and has an induction pipe depression of 2.4 ins. of Hg. By removing completely the suction piston and chamber the power is increased to 71.8 B.H.P. with a lowered depression of 1.6 ins. Hg. At 1000 R.P.M. the expanding carburetter gives 18.1 B.H.P. or 99.5 B.M.E.P. and the S.U. carburetter 16.8 B.H.P. or 92.6 B.M.E.P. the induction depression in each case being .6 ins.Hg. Distribution. The high speed distribution with both systems is very good and even, but down at the low speeds, 1000 R.P.M., the semi expanding carburetter is a considerable improvement upon the S.U. the latter being very susceptible to throttle position. Our unit bed dynamometer does not permit us to run below 1000 R.P.M. full throttle, but the distribution is so good at this speed that we can imagine it remaining so at even lower speeds full throttle. Suction Piston. As received the piston had a diametrical clearance of .002" both top and bottom in its chamber. At 2000 R.P.M. full throttle it became fully lifted, the maximum lift being .450". By increasing this clearance to .004" the piston was fully lifted at 2500 R.P.M. Besides delaying the lift as required, the increased clearance brings in the undesirable feature of an initial jump of the piston when the throttle is snapped open, and the high induction pipe depression transmitted momentarily to the suction chamber. Its effect is to spoil the acceleration under light loads. The piston was then weighted from 7 ozs. to 12 ozs. | ||