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).
Summary of pump modification tests 7 through 11, detailing changes to suction passages and ports and their effect on delivery rates.
| Identifier | WestWitteringFiles\W\September1931-November1931\ Scan081 | |
| Date | 13th November 1931 | |
| (-) SUMMARY CONTINUED 100 to 8 cc. made practically no difference to the maximum output - Test 7. Increasing the suction passage from .187" to .250" diam. increased the maximum delivery by approximately a further 20 pts/hr. but the reduction in delivery towards 2000 R.P.M. was as great as in most of the previous tests - Test 8. Increasing the inlet port to .250" diam. - Test 9 - proved to be no advantage, in fact the decrease at the end of the speed range was greater than before. Several results taken with the 100 cc "air bottle" showed little or no alteration to the 8 cc "air bottle" figures. Drilling out the short suction port (between the valve and the suction passage) to .218" diam. - Test 10 - effected an improvement in the higher speed results, but the maximum deliveries obtained were approximately the same as in Test 8. At the peak of the curve (which occurred just below 1000 R.P.M.) the delivery rose sharply, giving an increase over previous figures by roughly 20 pts/hr, but dropped quickly again to the previous maximum level. Increasing the valve ports to .250" diam.(from .234" diam) Test 11 - again increased the maximum delivery by 20-30 pts/hr. also the curve peak occurred nearer to 1500 R.P.M. than previously. Nevertheless the delivery decreased towards 2000 R.P.M. This was the final test so far as modifications to the pump were concerned and reviewing the position in the light of the present engine requirements, it will be seen that the delivery against a pressure of 1 lbs. sq". is just sufficient to cope with the estimated consumption (i.e. 100 pts /hr at 1750 pump R.P.M. or 3500 engine RPM). It will also be seen that these results are not equal to those obtained from the previous pump when tested under similar conditions, and with the same modifications. Except that the maximum pressure of the second pump was lower than that of the first, there was no discernible difference between the two units. The same springs were used in both pumps, and the compressed lengths of these springs in position were the same in both cases. All the above tests were taken with a direct flow inlet union and nipple on the suction side • to facilitate the adaptation of the "reservoir" - in place of the standard banjo fitting. continued. | ||