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 of engine compression curves at variable speeds and strokes.
| Identifier | ExFiles\Box 170\2\ img022 | |
| Date | 16th April 1931 guessed | |
| L 1650 COMPRESSION CURVES VARIABLE SPEED VARIABLE STROKE 7" ARM OG-GO VALVES 690"/° 2.50 2.38 1.58 1.00 7" STROKE 3.87 2.50 2.02 1.48 1.00 6" 5" 4" | ||