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 power drops, injector cooling, and the effects of different fuels.
| Identifier | ExFiles\Box 179b\3\ img206 | |
| Date | 14th February 1933 | |
| -16- From this test it is concluded that the sudden power drop noted at 100°C. jacket temperature was not due to the high jacket water temperature. In view of the performance of the nozzle in test 2f it is not safe to conclude that the unsteady power in test 2k is accounted for by the jacket temperature. From the above series of tests it was evident that the injector cooling was inadequate hence a copper tube was fitted into the cylinder as in C.I.1. PART 3. Copper tube fitted in cylinder head as in C.I.1. A 3-hour test was conducted (No. 3a) using a new Bosch nozzle. The B.M.E.P's and specific consumptions are plotted against time in Fig.10 from which it will be seen that the power is practically constant at 93 lbs/sq.in. and specific consumption .500 lbs/BHP/Hr. The temperature of the injector judged by feel, appeared to be considerably lower than in the preceeding tests but the needle valve tip still showed marked discolouration. It therefore seemed that the discolouration previously thought to be a sign of the injector overheating, was due to some other cause. It was considered that the fuel used might be the cause although laboratory experiments did not support this view. To settle this point in the engine and also to determine the effect on performance of a change in fuel, a test was run on Persian gas oil (3b) and the results are plotted in Figs. 11 & 12. A sudden drop in power from 96 lbs/sq.in. to 90.5 lbs/sq.in. occurred after 90 mins. running but for the first hour the power was maintained at 96 lbs/sq.in. After the power drop the B.M.E.P. fluctuated. Towards the end of the test fuel oil welled out of the pump camshaft lubricator and on stopping the engine it was found that excessive leakage was occurring past the plunger. This leakage probably caused the drop in power. The test was repeated using a new pump element and since the leakage past the pump plunger apparently affected the power it was thought that this effect must operate through a change in the fuel line pressure. In other words, fuel line pressure diagrams taken before and after the sudden drop in power might exhibit certain differences. The test results are plotted in Figs. 11 and 12 (3c). The power was very unstable, at 50 mins. the power dropped momentarily from 91 lbs/sq.in. to 85 lbs/sq.in. | ||