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 Brake Horsepower vs RPM for five different exhaust system configurations.
| Identifier | ExFiles\Box 181\M9\ img012 | |
| Date | 11th August 1931 | |
| RM.{William Robotham - Chief Engineer}26 COMPARISON OF EXHAUST SYSTEMS. CHINA 11/2 SHAFT HIGH LIFT ROCKERS 5.65 C/R STD 15% LARGER CARB. ① OPEN EX. ② PII EX. SYSTEM ③ W.W. Nsch3286 PII FISHTAIL ④ W.W. Nsch.3286 25HP FISHTAIL ⑤ STD. 25 H.P. SYSTEM ARRGT. E.55794 B.H.P. R.P.M. EXHAUST BACK PRESSURE IWS HG 11-8-31 | ||