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).
Ignition advance tests and analysis of turbulent lips on cylinder heads for the 20/25 HP and Bentley models.
| Identifier | ExFiles\Box 101\3\ scan0002 | |
| Date | 10th June 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to By.{R.W. Bailey - Chief Engineer} c. to Rg.{Mr Rowledge} c. to Nd. c. to Mx.{John H Maddocks - Chief Proving Officer} x500 Ignition Advance and Analysis of Turbulent Lips on Cylinder Head - 20/25 HP. & Bentley. We have been carrying out some comprehensive tests on the ignition advance required on the 20/25 HP. and Bentley. In each case curves were obtained independently on the test bed and on the road, to ensure that there was no marked discrepancy between actual driving conditions and test bench work. The results agree sufficiently closely to say that either method can be taken as giving correct results for ignition advance curves. Whilst carrying out the road tests we took the opportunity of checking up the effect on air temperature, mixture strength, etc. on detonation. The tests were divided into two main sections - (a) Investigation of the ignition advance required with the existing turbulent heads on the 20/25 HP. and Bentley. (b) Investigation of the ignition advance required with the heads having the turbulent lips removed, 20/25 and Bentley. The tests prove that on the Bentley we have got about the best ignition advance curve we can produce with the existing design of governor, except that we are providing rather more automatic advance than is necessary. In the future we are proposing to limit the maximum ignition advance to 30° before top dead centre on the Bentley. On the 20/25, the ignition advance curve at present being obtained is not correct. It rises too steeply, and furthermore there is 14° too much ignition advance at maximum speeds. A specification for the correct ignition governor is given on page 2 of the attached report Ha/Swdl.{Len H. Swindell}21/KW.9.6.36. We recommend that the 20/25 governors should be changed over immediately on production. A governor to the modified specification is being run on 22-U-V in France. | ||