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).
Road tests of Bentley V pistons with an increased compression ratio to improve engine performance.
| Identifier | ExFiles\Box 148\1\ scan0047 | |
| Date | 9th February 1939 | |
| Rm{William Robotham - Chief Engineer}/FD.{Frank Dodd - Bodies} from Rm{William Robotham - Chief Engineer}/FD.{Frank Dodd - Bodies} Rm{William Robotham - Chief Engineer}/FD{Frank Dodd - Bodies}2/R.9.2.39. BENTLEY V.{VIENNA} PISTON TESTS. We have carried out a series of road tests on the Bentley V.{VIENNA} with increased compression ratio, our object being to improve the snap opening, acceleration, and general liveliness of the engine. We have been able to do this by using raised crown pistons of 7:1 compression ratio, these together with a special ignition governor advance characteristic give excellent results, making a lively engine with a minimum of detonation. Comparing the Bentley V.{VIENNA} in this condition against the 'M' Series Bentley, we are quicker off the mark with the B.V., and are two seconds better up our test hill at Ticknall. Acceleration from 10-60 m.p.h. is 17.5 secs. for the B.V. against 19.5 secs. for the B.II 'M' series. There is, however no increase in the maximum speed of the Bentley V.{VIENNA} Attached is ignition curve required with 7:1 compression pistons. Rm{William Robotham - Chief Engineer}/FD.{Frank Dodd - Bodies} | ||