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 on engine air leakage measurement methods and results against varying RPM for a standard Phantom engine.
| Identifier | ExFiles\Box 66\1\ scan0111 | |
| Date | 12th October 1926 | |
| contd :- -2- Its/ACL1/LG 12.10.26 The amount of air used is measured by water replacement in a container having a calibrated gauge glass at the side. The action of the container is such that a small drop of pressure due to abstracting air results in its replacement by water which flows from a constant level tank situated at the top. The water has to be lifted less than a quarter of an inch and as this negative head remains constant we avoid all appreciable suction losses. A compression pressure gauge fitted to the cylinder shews the 'peak' pressure attained. We have carried out a test on the standard Phantom of 4.1 to 1 compression ratio to see what leakage occurred on compression. The water and oil was maintained at normal working temperature of 80°C and 60°C respectively. The following results shew how the leakage varies with engine speed :- Table X R.P.M. | Leakage cu.in/min. | Leakage cu.in/comp.stroke --- | --- | --- 500 | 184 | .368 750 | 208.5 | .278 1000 | 246 | .246 1250 | 319 | .255 1500 | 275 | .183 1750 | 168.5 | .096 2000 | 105 | .052 contd :- | ||