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).
Technical memorandum on manifolding and torsional vibrations, with comparative engine performance data.
| Identifier | ExFiles\Box 173\1\ img429 | |
| Date | 10th February 1934 | |
| -7- He/Rm.{William Robotham - Chief Engineer}9/KW.10.2.34. MANIFOLDING. There is now almost a standardised treatment of the straight eight induction system in which the exhaust and inlet are taken out on the same side and a simple hot spot arranged, with a thermostat controlled butterfly which by-passes the heat when once warmed up. By developing the materials the Americans have made this work every time, siamesed induction ports, four branch pipe for 8 cyls. This is not bad for M.E.P. because on the Cadillac 16, with a short duration camshaft having accelerations only 80% of ours, a carb. for each 4 cyls, expanding type, induction ports in no way more streamlined than the Bentley and 6.5 C/R, they have the following M.E.P. curve - R.P.M. 400 800 1200 1600 2000 2400 3600 B.M.E.P. 106 116 120.5 121 122 121 97 For a Rolls-Royce, as opposed to a Bentley, I think this is pretty good. Steaman should be able to show if a siamesed port fundamentally loses any volumetric efficiency. The M.E.P. for Cadillacs new La{L. A. Archer} Salle side valve eight is definitely down, partly because it is a side valve engine and again partly because it is using a fixed choke carburetter. La{L. A. Archer} Salle 240 Cu.Inch 6.5-1 C/R.{Sir Henry Royce} R.P.M. 500 1000 1500 2000 2500 3000 3600 B.M.E.P. 97 103 106 109 105 97 84 TORSIONAL VIBRATIONS. VEE 8 & A LINE 8. I saw the torsional vibration diagrams of the 8 shaft, particulars of which I have given. The 4 per rev. was at 3,300, the 8/rev. at 1600. I also saw the diagrams of the Vee 8. Curiously enough the 4/rev. period on this shaft was little higher than on the line 8, being about 3,300. There was a 3 per rev. period, presumably caused by inertia and not explosion, at about 4300 and at this speed they fractured several crankshafts. He/Rm.{William Robotham - Chief Engineer} | ||