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 development of a governor curve for Bentley V engines fitted with 7-1 raised crown pistons to correct for fuel variations and detonation.
| Identifier | ExFiles\Box 97\5\ scan0191 | |
| Date | 1st June 1939 | |
| 4006. To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/IMW.{Ivan M. Waller - Head of Chateauroux} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/Jnr.{Charles L. Jenner} c. Da{Bernard Day - Chassis Design}/Res. c. By/RD. c. Rm{William Robotham - Chief Engineer}/Swal. c. Rm{William Robotham - Chief Engineer}/RC.{R. Childs} c. RR. RM{William Robotham - Chief Engineer}/IMS.3/MR.1.6.39. BENTLEY V.{VIENNA} Development of governor curve to suit 7-1 raised crown pistons, and use of vernier control to correct for variations in fuels. On the first French test of B.S.V., unit No.5 fitted with 6.5-1 raised crown pistons was very good for freedom from detonation timed at T.D.C. with governor curve as Fig. 1. The performance was equal to present standard but owing to the increased smoothness, silence and comfort, it felt very much down on acceleration, and complaints in service were expected. The 7-1 raised crown piston was therefore developed and shown to give a useful increase in performance. They were fitted to B.S.V. for the second test and ran 31,800 miles, the results being most satisfactory when Azur or Discol was used, but on Ethyl light detonation occurred, whilst even on the best fuels obtainable in Italy or Germany, detonation was very bad. It did not come in at any particular speeds, being uniformly distributed through the range. It gradually died out with increase of speed, but did not completely disappear until 70 m.p.h. on some petrols in Italy. It appeared, therefore, that the governor curve lay within reasonable limits; and that retarding the ignition would eliminate the detonation at all points. The curve is shown in B, Fig. 1. Tests were continued at Derby on 7.B.V. after the running was completed on B.S.V. (i) To find if any improvement in governor curve could be obtained. | ||