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).
Tests concerning rotational air swirl, valve timing, and injection timing and duration.
| Identifier | ExFiles\Box 133\3\ scan0044 | |
| Date | 28th February 1939 | |
| -5- Rotational Air Swirl - Cont'd.{John DeLooze - Company Secretary} (c) Integrally Masked Valves of the Hesselmann type (similar to Leyland's) were tried, and gave a specific swirl of 5.9 at 2000 R.P.M., which remains fairly constant over the speed range. The volumetric efficiency was, however, seriously down, but could be regained to a great extent by increasing the valve lift to .600, lengthening the duration and employing only one masked valve. This latter move, however, resulted in a decrease in swirl ratio to 2.65. No power tests were carried out on this unit as on the instructions of the D.S.R. work on swirl was suspended. (d) Vened Inlet Ports inducing a swirl in the port were tried, but were found to be of little practical value due to the low volumetric efficiency (74%) accompanied by a specific swirl of less than unity. Valve Timing and Volumetric Efficiency. Within fairly wide limits the effect of valve timing on volumetric efficiency appears to be relatively slight, both long and short duration inlet cams giving approximately 82% efficiency at 2000 R.P.M. It should be noted, however, that these tests were run at constant speed only, and no doubt some effect would be observed over the speed range. With masked valves little reduction in volumetric efficiency results, but the integrally masked valves show a very poor efficiency, which can be improved by long durations and high lift cams, though not right up to the standard figure. Injection Timing and Duration. An electrical indicating device was developed to measure the actual time and duration and injection, and it was found that, for a given injection quantity of fuel, the injection duration increases with R.P.M. up to about 1,550 R.P.M. when it remains fairly constant, this with a fuel line capacity of .416 cu.ins. | ||