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 comparison between R and U series engines for the 25 HP cars, showing improved torque and power curves.
| Identifier | ExFiles\Box 107\1\ scan0120 | |
| Date | 1st November 1931 | |
| COMPARISON OF R AND U SERIES RM.{William Robotham - Chief Engineer}69. TABLE 1: CHINA 25 H.P. CARS TABLE 2 - U SERIES: 20 GTV CAMSHAFT E.57177 PISTONS E.57122 C/R 5.7 110.5 EXHAUST SYSTEM PJT SHORT TYPE BY/558/NIS. 11.31 TABLE 3 - R SERIES: GLR. 50 CAMSHAFT Sch 1153 COMP. RATIO 5-1 110° S-1 EXHAUST SYSTEM CHINA E.{Mr Elliott - Chief Engineer} 55794 TABLE 4 - IMPROVED TORQUE: IMPROVED TORQUE AVAILABLE VARIOUS ROAD SPEEDS U SERIES % BETTER THAN R 10 MPH: -3% 20 MPH: +1% 30 MPH: +4% 40 MPH: +8% 50 MPH: +14½% 60 MPH: +25% GRAPH AXES & LABELS: Y-AXIS: BRAKE MEAN EFFECTIVE PRESSURE LBS/SQ. IN. DIRECTLY PROPORTIONAL TO POWER AVAILABLE AT ROAD WHEELS X-AXIS: RPM, M.P.H GRAPH CURVES: 20 GIV GLR 50 VALVE TIMING DIAGRAMS: U SERIES: IN, EX, 2.6°, 35, 45 R SERIES: IN, EX, 10, 43, 54 | ||