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).
The compression ratio for the B.V. model, detailing road test results and standardisation considerations.
| Identifier | ExFiles\Box 148\1\ scan0046 | |
| Date | 9th February 1939 | |
| By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} c. Da.{Bernard Day - Chassis Design} c. Mx.{John H Maddocks - Chief Proving Officer} COMPRESSION RATIO FOR B.V. 6.5-1. Our present compression ratio on B.II is As the raised crown piston enabled us to raise the compression ratio on the test beds without increase in detonation, we carried out road tests to see if we could obtain confirmation of this result. The attached report shows that with these pistons, B.V. definitely has better performance than B.II, and, incidentally this is obtained for no increase in detonation. At 17,000 miles 8.B.V. now running in France was fitted with 7-1 pistons, and has now completed a further 15,000 miles. When tried the other day we considered the detonation was passable. The standarisation of this C/R depends on the condition of the pistons themselves, and the bearings after 25,000 miles. For the time being we have instructed 6.5-1 pistons for the first 50 cars as we cannot take any chances with reliability. Rm.{William Robotham - Chief Engineer} | ||