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 comparing the power (BHP) and BMEP of five different engine configurations with open exhausts.
| Identifier | ExFiles\Box 30\2\ Scan078 | |
| Date | 1st October 1932 guessed | |
| POWER COMPARISONS (OPEN EXHAUST) LEGEND: ① STD PHANTOM II - 7668CC ② CONTINENTAL PII (R.R. SEMI-EXP CARB R=5.25:1) 7668CC ③ CONTINENTAL PII (TWIN SU CARBS R=5.25:1) 7668CC ④ 12 CYL. 3"x4.5" J1 ENGINE (TWIN SU CARBS R=6.3:1) 6252CC 112º CAMSHAFT ⑤ 12 CYL. 3.25"x4.5" J1 ENGINE ( " " ) 7338CC AXES LABELS: Y-AXIS (LEFT): B.H.P. (FLYWHEEL) X-AXIS: ENGINE R.P.M. Y-AXIS (RIGHT): B.M.E.P. LBS/□" | ||