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).
Testing a new distributing pipe design, with a B.M.E.P. comparison table against the standard system at various RPMs.
| Identifier | ExFiles\Box 66a\1\ scan0139 | |
| Date | 1st August 1926 guessed | |
| CONTD:- -5- We have tested a pipe in which the entrance into the distributing pipe from the feed pipe consisted of a long narrow slot as shewn in sketch No.5. A std. Phantom carb. was used. The straight copper distributing pipe with the square bends used for some of the previous experiments was employed. The feed pipe followed approx. the same contour as the std. section at the carb. to a narrow slot - 6.000 X .400Ø - at the distributing pipe. The results were very good and torque was maintained right down to the lowest speed. The engine would accelerate without any 'missing' under load and would not 'load up'. The position of the throttle did not influence the distribution in any way while the standard system is very susceptible to change of throttle opening when cold. This is the only pipe we have tried which, with the std. carb., will give us the good results stated above when run cold. The following table is a comparison of the B.M.E.P. obtained with the standard system. All the tests described in this report have been conducted with no pre-heating. | R.P.M. | Std. | B.M.E.P. (cold) Expl: (sketch 5.) | |--------|--------|---------------------------------| | 2500 | 71.2 | 70.5 | | 2250 | 81 | 80.5 | | 2000 | 87.75 | 88.5 | | 1750 | 90 | 93.5 | | 1500 | 95 + | 98.75 | | 1250 | 95 + | 100.5 | | 1000 | 95 + | 100.0 | | 750 | 89 + | 100.5 | | 660 | 82 + | 101 | Note :- With the standard system, readings marked + were the best that could be obtained by adjusting the throttle to correct distribution. The running below 1500 was very erratic with standard system. contd :- | ||