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).
Graph showing the relationship between compression ratio and octane number for various engines.
| Identifier | ExFiles\Box 150\1\ scan0074 | |
| Date | 12th November 1935 guessed | |
| RELATION BETWEEN COMPRESSION RATIO & OCTANE Nọ FOR VARIOUS ENGINES OCTANE NUMBER C.F.R Motor Method COMPRESSION RATIO CFR Engine (Motor Method) Two S.V. Water cooled cylinders typical of American Motor car Practice •15 Ratio per ON •06 Ratio per O.N. | ||