Table of test results showing Brake Horsepower (BHP) and power loss for various exhaust system configurations at 4,000 RPM.
| Identifier | ExFiles\Box 8\8\ 08-page59 | |
| Date | 18th June 1938 guessed | |
| 4,000 R.P.M. B.H.P. LOSS. OPEN EXHAUST. 98.3 MANIFOLD ONLY 96.4 1.9 MANIFOLD & FRONT EXP. BOX 91.2 7.1 " " & INTER BOX 89.7 8.6 " " without top hats & rear silencer. 87.4 10.9 " " top hats 45 holes " std. rear silencer. 84.0 14.3 COMPLETE WRAITH EXHAUST SYSTEM WITH 1½" TAIL PIPE. 74.0 24.3 " " " " " 1¾" TAIL PIPE. 80.5 17.8 STRAIGHT THRO' 2" PIPE FROM MANIFOLD - TOTAL LENGTH 110". 92.1 6.2 Front EXP. BOX & 2" PIPE - TOTAL LENGTH 110". 89.5 8.8 STRAIGHT THRO' FRONT PIPE, INTER BOX & STD. REAR SILENCER. 90.6 7.7. AS ABOVE WITH 1½" TAIL PIPE 79.1 19.2 " " " 1¾" TAIL PIPE 86.2 12.1 | ||
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).