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).
Performance comparison between a standard and a deturbulated cylinder head for the 25/30 model.
| Identifier | ExFiles\Box 103\4\ scan0181 | |
| Date | 5th November 1936 | |
| 519 E.{Mr Elliott - Chief Engineer} C. By.{R.W. Bailey - Chief Engineer} C. Da.{Bernard Day - Chassis Design} Rm{William Robotham - Chief Engineer}/Swd112/R.5.11.36. 25/30 Cylinder Head Comparisons. From the attached curves are deduced the following results:- (1) The deturbulated head given an increase over standard of 2 m.p.h. at maximum speed, despite the fact that the deturbulated head is 5.86 as against standard at 6.0:1 (2) From the engine movement-charts, the deturbulated head is smoother in all conditions. (3) Deturbulated head has slightly better acceleration 5 - 70 m.p.h. Nothing in heads 5 to 40 m.p.h. (4) That the detonation stays with you in the standard head to the extent of 2 m.p.h. more than with the deturbulated head, although the intensity of detonations are almost identical when in the limit of their range. (5) Assuming from the advantages given by the deturbulated head that this is standardised, the best all round ignition setting is as follows:- For other than the results shown it must also be borne in mind that the most retarded static timing will give best idling. H.{Arthur M. Hanbury - Head Complaints} Hamilton governor with a timing of 11°B.T.D.C. comprising EB2832 Governor frame. E61099 - 9 coil springs. Figures this gives are:- 5/40 m.p.h. 5/70 m.p.h. Max. Speed. Det'ns.{Norman Scott} Fade Intensity. 16.15 secs. 45 secs. 76 12 mph. Faint. Irrespective of timing, maximum performance figures with deturbulated head are:- 15.65 - 42.5 - 77.25 Rm{William Robotham - Chief Engineer}/L.H. Swindall. | ||