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).
Engine performance issues including vibration, slow running, oil temperature, and water circulation.
| Identifier | ExFiles\Box 133\1\ scan0119 | |
| Date | 17th September 1936 | |
| -15- Miscellaneous. I. Vibration. A great deal of trouble was encountered on the unit due to excessive vibration. This started at about 4,500 R.P.M. and reached a maximum at 5,000 to 5,250 R.P.M., and then gradually diminished up to the top speed of 6,000 R.P.M. No serious attempts were made to cure it, as it was not expected that running on the unit would go on as long as it did, but it is fairly certain that the cause of the vibration was the extreme rigidity of the engine mounting. This vibration it is assumed was also the cause of the successive failures of the Hardy fabric discs, about twenty of which were used during the life of the engine. II. Slow Running. As will be seen above, the slow running at full throttle of this engine was very poor. The reason for this is put down to the absence of any heavy flywheel, and the slow gas velocity through the choke at speeds below about 3,000 R.P.M. Overlap had some effect on the slow running speed, and it was also improved quite considerably by fitting a petrol pump and variable jet, and doing away with the float chambers. III. Oil Temperature. Under normal running conditions on the air cooled unit, the air blast on the crankcase kept the air cool, and it remained almost stone cold. With the water-cooled unit, however, there was no oil cooling and the oil temperature rose tremendously, ultimately causing a big end failure. For running after this an oil cooler was incorporated. IV. Water Circulation. An attempt was made to use Ricardo's injection system of water cooling, but unfortunately, the water pressure available was too low (17 lbs/in.2), and the system did not produce a very satisfactory flow, only about half a gallon per minute, giving a temperature difference at inlet and outlet of nearly 20°C. | ||