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).
Test report comparing the performance of a single horizontal carburetter against a single downdraught carburetter.
| Identifier | ExFiles\Box 93\2\ scan0052 | |
| Date | 8th July 1935 | |
| -3- HA/CTS.{C. Trot Salt - Carburation}16/RH{R. Hollingworth}/8.7.35. Test No. 3. Figs. 4 & 5. Standard pipe as Test 1, comparing :- (1) Single horizontal carburetter. (2) Single downdraught carburetter. Result. Slow Running: (2) is 50% better than (1). Pick up: Same in each case. Power: See curve No. 2. Distribution:(2)is a big improvement over the whole range. Reasons: The general improvement we believe to be due to the following: Considering the "wet" mixture in each case, on the horizontal carb. a large proportion of the heavier mixture enters and deposits itself on the floor of the main pipe, the effect being felt most acutely on the centre cylinders. This is very apparent at tick-over speeds, as when the nearest to correct mixture is obtained by adjustment for the centre cylinders, the outer cylinders are too weak for complete combustion. With the downdraught carburetter, the unvaporised fuel (even though coming down the walls of the riser) drops into the main gas stream and is more freely whirled about. The quality of this tick-over is not reliable enough, however, due to the fact that, although the "wet" stuff is being whirled about with better distribution, it is still not being evenly distributed. Also there are still distinct signs of starvation in the outer cylinders | ||