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 comparing carburetter performance with different pipe configurations and engine types, including M.E.P. data.
| Identifier | ExFiles\Box 5a\5\ 05-page179 | |
| Date | 17th November 1931 | |
| -2- Ha/Rm.{William Robotham - Chief Engineer}1/WJ.17.11.31.Cont'd.{John DeLooze - Company Secretary} the lower the depression at which the carburetter works (or larger the carburetter) the more critical the distribution becomes, and for this reason are very satisfied with the horizontal 'T' pipe tested. The M.E.P. of J.1 is beginning to compare favourably with that of the four litre 6 cyl Bentley. M.E.P. 1500 R.P.M. 3500 R.P.M. C.R. 5.65 Japan 1 ...... 112 102 C.R. 5.05 Bentley ...... 101 100 You will note that on this last test we used two exhaust cam forms on the 112° V.T. camshaft. This seems to increase the top B.H.P. by only 2 or 3% but raises the peak of the power curve 250 R.P.M. It is not really of much interest as the inlet remains open too long to give a reasonable low speed M.E.P., and we should expect that a longer exhaust cam duration would be required with such an inlet cam. Summarising our conclusions. We have only shown that a horizontal 'T' pipe is better than a bend. We are now putting exactly the same size of 'T' pipe only arranged as a vertical carburetter, on the vertical 'T' pipe which has given us such good results with the Cloudel. We expect that this may overcome our very low speed distribution troubles and demonstrate what we at present believe, that the best pipe is the vertical 'T' that you have given us with the new single carburetter. He/Rm.{William Robotham - Chief Engineer} | ||