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).
Piston compression ratios and ordering instructions based on recent B-V engine tests.
| Identifier | ExFiles\Box 148\1\ scan0166 | |
| Date | 12th June 1939 | |
| 1258 + 436 Les.{Ivan A. Leslie} from Rm.{William Robotham - Chief Engineer} c. By.{R.W. Bailey - Chief Engineer} Rml2/R.12.6.39. During the recent hot weather we have been carrying out a number of tests on the B-V to ascertain whether the freedom from detonation with the 7:1 piston is adequate for the normal customer. We are satisfied that the average owner would prefer the 6¾:1 piston, particularly in view of the fact that a Continental car is now available for anyone who wants superlative performance, Will you, therefore, please instruct 300 sets of pistons to be ordered with 6¾:1 compression ratio raised crown. The 50 sets already ordered can be supplied to customers requests for higher compression. Since the design of the engine is stabilised for 500 or 600 cars, we do not think there will be any difficulty in using up these pistons. Rm.{William Robotham - Chief Engineer} | ||