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).
Series of tests on cylinder blocks, injectors, and nozzles to investigate power loss and cooling issues.
| Identifier | ExFiles\Box 179b\3\ img194 | |
| Date | 4th February 1933 | |
| En/Td.1/AM.4.2.33 contd. -4- Tests Series 1 were conducted while awaiting the new cylinder block which was bored to fit the Bosch injector and the injector was externally water cooled as previously described. The subjects of these tests were supercharging and the effect of inlet valve diameter on compression pressure and volumetric efficiency. Tests Series 2 in which the cylinder block was bored to fit the Bosch injector were next run and it was found that the nozzle was still inadequately cooled. Test Series 3 were not started immediately, however, as in several tests a power equal to that of C.I.1 (when allowance was made for the difference in the motoring losses) was obtained but unfortunately never held for long. The characteristic of these tests was either a gradual or a sudden loss of power sooner or later after putting the engine on full load. A number of tests was conducted to try to determine the fundamental cause of this power loss as it was felt that if this could be achieved the power equal to C.I.1 would be permanently regained. Tests Series 3 (copper tube inserted in cylinder block and water circulated round this) were commenced when it was realised that without improved cooling of the injector a steady power could not be maintained. The power was now steady when everything was in order. In the tests in which there was a power drop the cause was definitely known. In Tests Series 4 a separate water supply was fitted to the injector jacket as it was thought that by cooling the injector more than in Series 3, a further improvement in performance might be obtained. This was found not to be so. It was then discovered that carbon tended to form in the nozzle holes and cause a loss of power. With clean holes there is then a steady power figure of 95.6 lbs/sq.in. and specific consumption of 0.477 lbs/BHP/Hr. i.e. about 3 lbs. B.M.E.P. below C.I.1 when allowance is made for the difference in the motoring losses. A further difficulty in getting a consistent power figure was encountered when using nozzles of R.R. manufacture as the needle valve seat could not always be ground concentric with the bore. From the fact that a power loss resulted from a carbon deposit in the nozzle holes, it was thought that increasing the diameter of the holes might lead to an increase in power but this was found not to be the case. With the aid of the schedule of tests and the above remarks it is hoped that the conceptions underlying and directing this research may be apparent. The tests are described in some detail at the end of the schedule and the various investigations are summarised at the end of the report. | ||