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).
Performance comparison graph for Aluminium versus Cast Iron Bentley cylinder heads.
| Identifier | ExFiles\Box 86\1\ scan0058 | |
| Date | 10th March 1938 | |
| B.V.24. CYLINDER HEAD COMPARISON (BENTLEY) UNIT: B.4.A. ① ALUMINIUM CYLINDER HEAD (COMPRESSION RATIO 7.38:1) ② CAST IRON COMPLETE AIR SILENCER & TEST BED EXHAUST SYSTEM MAX. IGNITION ADVANCE AVOIDING DETONATION B.M.E.P. WITH IGNITION SET TO AVOID DETONATION R.P.M. ADMS 10-3-38 | ||