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).
Various engine tests and modifications including injection timing, piston experiments, and cylinder modifications.
| Identifier | ExFiles\Box 133\3\ scan0066 | |
| Date | 6th March 1939 | |
| -6- Rm{William Robotham - Chief Engineer}/Td.4/MH.{M. Huckerby}6.3.39. Mechanical Efficiency. A check was carried out on previous results which were found to be substantially accurate. Effect of Injection and Exhaust Valve Timing on Starting. Retarded injection (25°-30°) gave a smooth quiet start, but 40°-45° advance produced severe thumping and excessive pressures. Ramming Induction Pipes. The general effect was very small, lengthening the pipe having the effect of reducing the speed at which optimum compression pressure sets in. This increase in pressure, however, does not appear to be reflected in increased power output. Piston Experiments. The "short range" piston described before, did not give sufficiently encouraging results to warrant further time being spent on it, and it was heavy and difficult to make. A flat topped piston which was a sound production job was nearly 10 lbs/sq.in. down for power. Compression Ratio. A reduction of C.R. from 14.2 to 12 : 1 gives a power drop of approximately 4% at normal injection. (B) Tests Carried out on Modified Cylinder. Modifications. (a) Two liners- one a dummy - to represent conditions of bolting at the end of a block of six (b) Larger inlet valves 2.050" dia. (original size 1.950") with flat heads. (c) Exhaust camshaft to take combined pump and injector. | ||