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).
Analysis of engine performance and distribution with different pipe arrangements and throttle settings.
| Identifier | ExFiles\Box 31\5\ Scan147 | |
| Date | 7th March 1934 guessed | |
| -2- Under all conditions the distribution with this pipe was very good at speeds above 1500 r.p.m. full throttle. With the pipe inverted, i.e., above level of ports in head, the distribution was good at speeds below 1500 r.p.m. With the pipe the standard way up the distribution was not good below 1500 r.p.m. and max. power was obtained with the throttle partially closed. The output obtained with the two arrangements of the pipe is shown on Sheet No. 2 attached. The way in which the throttle valve opened had no effect on either the power or distribution. At speeds above 2500 r.p.m. the output with the pipe the normal way up is slightly the greater. This may be due to the 1½" distance pieces which had to be used with the pipe in the inverted position. The effect of these was to increase the length of the passages between the pipe and the valves. The output obtained on a different engine (Unit B.7) with a 1⅜" carburetter (S.U.) (Lec.3688) on the opposite side of the engine, with a 1.200" dia. hole through the block and all other conditions similar, is also shown on The gain in output due to the elimination of the hole through the block is very small. This suggests that with the 20/25 type of head and a 1.200 dia. hole through the block the principal restriction limiting volumetric efficiency occurs in the head and not between the head and the carburetter. HS{Lord Ernest Hives - Chair}/F.J. Hardy. | ||