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).
Bar chart comparing lap speeds of a 25 HP car with various engine and axle modifications at Brooklands Track.
| Identifier | ExFiles\Box 29\3\ Scan343 | |
| Date | 26th August 1931 | |
| 25 H.P. CAR. IMPROVED HIGH SPEED PERFORMANCE. I. BROOKLANDS TRACK. LAP SPEED. 65.87 M.P.H. STANDARD ENGINE AND CAR. 11/50 AXLE. 67.57 M.P.H. STANDARD ENGINE S.U. CARBURETTER. 11/50 AXLE. 72.49 M.P.H (73.45) SPECIAL ENGINE R.R. CARBURETTER. 11/50 AXLE 73.6 M.P.H (73.6) SPECIAL ENGINE R.R. CARBURETTER. 12/50 AXLE. 75.23 M.P.H. (76.62) SPECIAL ENGINE S.U. CARBURETTER 11/50 AXLE 76.39 M.P.H. (78.43) SPECIAL ENGINE S.U. CARBURETTER 12/50 AXLE. 65.52 M.P.H (70) JAPAN I (16GIV) SPECIAL ENGINE SIGNIFIES:- MODIFIED VALVE TIMING, VALVE LIFT, COMPRESSION RATIO AND EXHAUST SYSTEM (THE FIGURES IN BRACKETS REPRESENT CUT OUT OPEN SPEEDS, THE INCREASE IN SPEED BEING INDICATED BY THE FULLY SHADED AREA) A J LIDSEY | ||