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).
Increased performance tests of a 27-EX car at Brooklands track with non-standard engine parts.
| Identifier | Morton\M19\ img255 | |
| Date | 5th October 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Sg.{Arthur F. Sidgreaves - MD} c. WOT. R.{Sir Henry Royce} c. Da.{Bernard Day - Chassis Design} Ev.{Ivan Evernden - coachwork} X.7120. X.7771. X.788. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}1/AWR.5.10.31. P.II INCREASED PERFORMANCE. BROOKLANDS 5.10.31. 27-EX car was taken to Brooklands track with the idea of finding out the best obtainable speeds using engine parts which could be adopted as standard on P.II Continental cars. The engine had the following non-standard equipment :- West WitteringHenry Royce's home town 114° camshaft (L.82449) Modified R.R. twin choke carburetter (LeC.2905/6) fitted with an experimental air intake silencer. 4.8 : 1 compression ratio In addition to the above modifications affecting power output, Diamond engine mounting was employed. The fuel system used was Autovac (operated from the induction pipe depression) and owing to the small available head of petrol an Autopulse electrically operated pump was employed in the gravity fuel line from the autovac to the carburetter. This system was used because the engine was fitted up with the latest R.R. fuel pump which was found not capable of supplying sufficient petrol to drive the car at a greater speed than 55 M.P.H. in top gear. At top speeds (65 to 90 m.p.h.) the engine is very smooth, much more so than before diamond engine mounting was employed. The most objectionable feature noticed was a roar from the carburetter at full throttle at speeds above 55 m.p.h., this is not due to the camshaft (we have tested with later valve timing which makes no difference, and with standard R.R. carburetter, when the roar disappears). Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} | ||