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).
Report page on engine testing, detailing vibration analysis, valve performance, and general conclusions.
| Identifier | WestWitteringFiles\Q\February1927-March1927\ 113 | |
| Date | 25th January 1926 guessed | |
| contd : -9- It is possible that this difference is partly or wholly accounted for by the lower gas velocity past the valves and the quicker opening and closing in the case of the Lorraine. MISCELLANEOUS DETAILS. The valves were examined up to a speed of 3250 RPM. by means of the oscilloscope and no signs of bounce could be detected. The four bearing crankshaft - particulars of which have previously been submitted - possesses a bad torsional vibration at 1950 r.p.m. This is the half speed vibration or one corresponding to six complete cycles per revolution. A light hub carrying the standard 20 HP. slipper wheels having the std. friction setting was fitted to the crankshaft in place of the fan pulley and proved effective in damping out this vibration to the extent that it was not evident by 'feel' or sound when on the test bed. This half speed vibration does not seem any more severe than experienced on the 20 HP. when it is run without the damper wheels. The engine accelerates well and there is no evidence of 'flat spots' due to the carburetters which are however set rather rich. SUMMARY & GENERAL CONCLUSIONS. The engine gives a very good performance for its size but, like most of the continental sports cars, is rather noisy in operation - chiefly valve gear and timing gear rattles. contd :- | ||