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).
Comparing the 40/50 HP engine to the 20 HP engine using an indicator diagram.
| Identifier | WestWitteringFiles\K\December1923\ Scan75 | |
| Date | 12th July 1923 | |
| B.R. 403A (40 H) (SL 42 12-7-23). J.H. D.{John DeLooze - Company Secretary} ORIGINAL EXPERIMENTAL REPORT. Expl. No. 4580 REF: Ha/Bal/1.0201.223. To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to RG.{Mr Rowledge} c. to H.{Arthur M. Hanbury - Head Complaints} c. to De. c. to OY. 40/50 HP. INDICATOR DIAGRAM. This diagram is an average of cards taken from representative cylinders. We find there is more variation between different cylinders on the 40/50 HP. engine than on the 20 HP., more especially between the inside and outside cylinders - i.e., 3 and 1. The I.M.E.P. of the former is about 3 lbs/sq.in. higher than the latter at 2000 r.p.m. It will be noticed that the positive bump at the end of the exhaust stroke which was so noticeable on the 20 HP. light spring diagram, is in this case, almost non-existent. We believe the reason for this is that the two exhaust systems are different. The absence of this bump and the fact that we did not get a 'roar' on the 40/50 supports our previous conclusions that the two are interconnected. The volumetric efficiency as shown from this diagram is lower than that of the 20 HP. The I.M.E.P. is naturally lower than that of the 20 HP. owing to the lower compression ratio, - the mechanical efficiency is slightly lower than the mean value we have obtained for G.11. engine at this speed. The negative work done on the piston of the 40/50 HP. appears to be more than 30% greater than that of the 20 HP., amounting to over 4 1/2 lbs/sq.in. in I.M.E.P. It would contd: | ||