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).
Power output tests for the Phantom II engine, analysing the effects of camshaft and inlet valve modifications.
| Identifier | ExFiles\Box 13\2\ 02-page133 | |
| Date | 18th September 1931 | |
| To R.{Sir Henry Royce} from HS{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. Ds. Py. 87090 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/AD18.9.31. POWER OUTPUT P.II. x7771 Attached are the results of a number of tests on the P.II to obtain the best power output with the W.W. 114° shaft. They consist of an analysis of the effect of (1) Inlet valve duration. (2) Inlet valve lift. (3) Size of inlet valve. (4) Carb. depression and disposition. on the behaviour of this camshaft. (1) Inlet Valve Duration. Rm.{William Robotham - Chief Engineer} P23. This is a direct comparison of the three camshafts we have tested having 223°, 241° and 272° inlet valve duration respectively when studied in conjunction with curves Rm.{William Robotham - Chief Engineer}P19 and Rm.{William Robotham - Chief Engineer}P12 they enable the effect of valve duration only to be deduced as in these latter curves a value for increased valve lift with the shorter duration camshaft is obtained. Height of Valve Lift. Rm.{William Robotham - Chief Engineer} P22. A comparison of increasing the valve lift .650 on a 114° etc.2916 camshaft and standard head. This also gives the best average power obtainable with the standard head and 114° shaft. Rm.{William Robotham - Chief Engineer} P20. As above but with the inlet valve throat reduced to 1.680. Outside dia Valve head 1.830 Rm.{William Robotham - Chief Engineer} P19. The same test carried out on an old cast iron head made when we were experiencing blocked radiators with inlet valves having a throat dia. of 2.0" and the head machined above the valve to give a minimum clearance between valve and head of .200. Outside dia Valve head 2.100 It should be noted that .650 increase in lift only represents 11.7% increase on P.II 114° shaft but 14.5% increase on the 25 HP. car. | ||