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 detailing the compression pressures of an 'SS' engine (No. SS-3) across a range of speeds.
| Identifier | WestWitteringFiles\S\September1928-October1928\ Scan090 | |
| Date | 28th September 1928 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c. to BJ. WoT. c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to SY. S E C R E T. Hs{Lord Ernest Hives - Chair}/ACL1/LG28.9.28. ORIGINAL 'SS{S. Smith}' ENGINE. X777 (struck through) X7770 / X790 Engine No.SS{S. Smith}-3. Total running time to date = 38 1/4 hrs. Running conditions. Claudel Hobson carburetter (Eagle 1X). Hot-spot in action (water temp: = 75°C) Exhaust manifold fitted, and bed exhaust system. 116° Crankshaft - Cam forms E.77854/5. The compression pressures of this engine have been ascertained throughout the speed range for each individual cylinder; the results being tabulated below :- Max: comp: pressure (lbs/sq.in). R.P.M. | No.1. | No.2. | No.3. | No.4. | No.5. | No.6 cyl: -------------------------------------------------------------- 3000 | 86.5 | 86.5 | 88.5 | 88.0 | 86.5 | 84.0 2500 | 90.5 | 93.0 | 93.5 | 95.0 | 92.5 | 90.5 2000 | 94.5 | 95.5 | 95.0 | 95.0 | 95.0 | 94.0 1500 | 94.5 | 94.0 | 95.0 | 95.0 | 93.0 | 93.5 1000 | 86.5 | 86.5 | 88.5 | 87.5 | 86.5 | 87.0 750 | 89.0 | 88.0 | 89.5 | 89.0 | 88.0 | 89.5 The average figures for the above are plotted on V.431. Tests to ascertain the mechanical efficiency have also been carried out, the results being given on V.432. The method used was that in which the loss of torque is noted when the cyls. are cut out one at a time, the speed being kept constant. The Claudel Hobson carb. has been removed and a standard Phantom carburetter fitted in its place, by means of a contd :- | ||