Test report on engine smoothness, noise, and performance at various speeds and with different fittings.
| Identifier | ExFiles\Box 5a\1\ 01-page112 | |
| Date | 20th April 1933 | |
| FL.23. 85770 20.4.33. 18.G.IV. 1st. Test of the above to get an impression of it I was struck by the smoothness of the engine at high speed. On top gear I noticed some roar at 47 m.p.h. points to timing being a little early. On top gear on the overrun there is a peculiar rough rattle at 43-40 m.p.h. this goes on the least pick up, it appears to get worse as the job warms up, would suggest a change of axle if not already proved otherwise. When trying the engine for max. revs. for valve clatter, weak springs etc. I found that this engine will rev. up to greater speed than a standard production engine, I got 54 on 3rd. and of course came up on the master period of the shaft. I have found since that it has balance weights on shaft. The car performance above 20 m.p.h. is about the same as production but below, could do nothing, misfires and carburation bad, could not take hills at all from low speeds. The exhaust system sounds thin and outstanding. The large bottle type expansion box is fitted. For booming the car is generally very good with the light contact rubber feet and the Y. bracket at rear. The engine fitted when above test was made had the C.I. crankcase. Unit C.9. Test with solid engine feet. 2nd. Test After fitting above with Y. bracket still in position booming is bad all up the scale and can be got with car stationary, and revving the engine up. On top gear I cannot determine any peaks of engine periods, but the boom comes on bad at 50 - 53 m.p.h. forward and is much worse on retard from 50 down to 35 m.p.h. On 3rd. gear light periods were noticed at 18 - 35 - 42. The retard rattle at 40. was unaltered by the above. | ||
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).