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).
Carburation, discussing the trade-off between power and fuel economy, illustrated with a performance graph.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan164 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -9- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Ral/LG21125 gradual stop with the throttle closed. Again, the average speed of the car almost always is increased when driving with front wheel brakes. This in itself gives an adequate reason for increased petrol consumption. CARBURATION. It is not generally realised that if a carb. is set for min. petrol consumption to give max. power, the car will still not be running under its most economical conditions. A small amount of power must be sacrificed if economy is of primary importance. A much more potent factor, however, is that the mixture can be very much over-rich without any falling off in power and performance. This is quite clearly shewn in Graph lV., the GRAPH IV [Graph with Y-axis labelled 'B.H.P. AND PERCENTAGE INTERNAL EFFICIENCY AT 1000 RPM' and X-axis labelled 'PETROL PER LB. OF DRY AIR.'. The graph shows two curves, one for 'EFFICIENCY' and one for 'B.H.P.', plotted against the petrol-air mixture. Dashed lines indicate 'CHEMICALLY PERFECT MIXTURE' and 'MAXIMUM POWER'. A handwritten note reads: 'Typical curves for efficient 4-stroke petrol engine.'] contd :- | ||