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 results on the petrol pump's compression ratio and its effect on engine starting.
| Identifier | ExFiles\Box 17\5\ Scan137 | |
| Date | 17th August 1932 | |
| 87460. R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to Sg.{Arthur F. Sidgreaves - MD} c. to WOr.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to Sy. c. to Da.{Bernard Day - Chassis Design} Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}4/MA.17.8.32. The attached report shews the results of trying out E's suggestion of increasing the compression ratio of the petrol pump. For ordinary conditions of running out on the reserve, when the starter motor can turn the engine at about 100 R.P.M., reducing the clearance volume 30% only reduces the time taken to draw from the reserve by 12%. Deleting the filter and tap from the pipe line, however, makes five times as much difference, and we are making tests to see how much we can take advantage of this. At the slower speeds the compression ratio has more effect, and this is important because a recent test shewed that with a 3.25 C/R head the starter motor will only rotate the engine at 56 R.P.M. under ordinary cold conditions of starting (10°C). We think the reason the Americans get away with the A.C. pump as it is, is that they turn their engines rather faster for starting. J.III should be better off as the suction pipe does not have to run to the front of the engine. Test may shew that we can use a smaller dia suction line and yet not spoil our high speed delivery. Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} Att: Hs{Lord Ernest Hives - Chair}/Hl.2/M A.18.6.32. | ||