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 graph plotting M.E.P (Mean Effective Pressure) in LBS Per SQ Inch against Ft Lbs.
| Identifier | Morton\M7\ img070 | |
| Date | 5th May 1921 guessed | |
| & M.E.P Ft LBS: 180 60 (LBS. PER SQ. INCH.) 70. 210 80. 240 90. 270 100. 300 | ||