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).
Experiments with intake pipe and carburetter designs to improve fuel distribution and power output for the J.1 engine.
| Identifier | ExFiles\Box 5a\5\ 05-page178 | |
| Date | 17th November 1931 | |
| 85771 To R.{Sir Henry Royce} From Ha/Wm. c. to Sr. Wor.{Arthur Wormald - General Works Manager} c. to S. Da.{Bernard Day - Chassis Design} c. to Hy.{Tom Haldenby - Plant Engineer} Ha/Rm.{William Robotham - Chief Engineer}1/M.17.11.31. x5080 DISTRIBUTION AND POWER OUTPUT. J.1. You will recollect that we managed to obtain good power with a 1 7/8 throttle dia. horizontal S.U. but we could not get the distribution satisfactory with the pipes as shown on No.51. We therefore built up a pipe as shown in the attached photographs, in which the carburetter was as close as possible to the induction pipe directly between cyls. 3 and 4. This pipe gave considerably the best distribution we have so far had with a horizontal low deps. carburetter, in fact, the results were excellent down to 1000 R.P.M. where the distribution became unstable. (Shown on the curve) The big fall in M.E.P. at 500 R.P.M. is of course partially due to the late closing of the inlet valve with this camshaft. We did not expect this pipe to be any good because with a fan shaped spray from the jet as on the S.U., we thought cyls. 3 and 4 were bound to be rich. However, as every bend has been used for distribution and 3 & 4 cyls. have always been weak, the above pipe seemed logical, especially as two small carburetters worked well on 'T' pipes placed right close to the induction pipe on the 40/50. In parallel with these tests we have been trying single large carburetters on the 40/50 and again to get them under the bonnet have been using various bends with which the distribution has been unstable and bad. Our conclusions therefore are that once the mixture has been thrown on the side of the pipe by rounding a bend, it is most difficult to distribute it even with a super hot spot. We have used a blow lamp on some of the bends on the 40/50 without success. The three 'Y' pipes we have been using, two vertical with Claudels and one horizontal with the S.U. have shown the most promise of any. We are therefore proposing to try such a pipe with our standard 40/50 carburetter, as we may possibly get better distribution than with the weir. We have had the Claudel on the weir pipe and on the whole the results are not so good as when we use the straight forward vertical 'Y' pipe. Generally speaking, on a carb. like the S.U. where we can try all sizes made to exactly the same scheme, we find that | ||