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 tests concerning high oil pressure, poor petrol consumption, and a 50 mph engine boom.
| Identifier | ExFiles\Box 1\4\ B001_X 100a-page201 | |
| Date | 6th February 1933 guessed | |
| compartment as shown in the sketch we sent you. To observe that we were not starving the camshaft we fitted a glass tube connected to the bottom of the ignition tower. The height of oil in the tube showed that at any speed above 200 engine revolutions ample oil was being delivered to the camshaft. The oil pump is very efficient and is delivering quite 50% more oil that what is needed. The release valve unit as fitted to this engine has not as yet been tested for the pressure of oil being delivered to the rockershaft bearing and housing of dynamo drive. This pressure must be too high as we are getting a quantity of oil thrown out of the breathers on the rocker cover. Now that we have somewhat settled these problems we shall carry out the test of reducing the amount of oil in the sump as you requested. We are very interested in your remarks re the heat to the oil. Our oil is absorbing approximately 25% of heat as our average water temperature is 77.1° and our average oil temperature 76.6°, therefore that increase in temperature must be what the oil is absorbing from the engine. We shall try the Potts' oil cooler as soon as we have tried the different quantities of oil in the base chamber. The leaflet you sent over with a small radiator in the water system would appear to give beneficial results. RE. PETROL CONSUMPTION. We have tried to reduce our petrol consumption by adjusting the high speed jet, but find that at maximum speeds we have only been able to weaken a high speed jet, a very small amount, which does not show any improvement upon the petrol consumption. We are amazed at the figure you give for the duo S.U.'s as the last car over here, our lowest consumption was 14 mpg and our average consumption worked out at approximately 13.5. This car is certainly worse, but when one takes into account the difference between acceleration of this car and previous car, the difference in the petrol consumption is not alarming. We grant that it is very poor and will have to be improved. RE. BOOMS. We are trying to get at the 50 mph boom. This was not pronounced until the car came out of the shop the last time after having had the new silencer fitted and the damper on the propeller shaft. These two items are the only two features which were altered, which would account for the boom. The boom does not follow with the speed, i.e. in third gear it is not at the same engine revolutions as on top gear. At 50 mph our engine is turning over at 2,900 revolutions as against the chart giving 3,050; we are only 100 revolutions out. You stated in your letter that the flywheel period is at approximately 4,000 revolutions. We have been up to 4,700 revolutions and have not noticed any marked period. However we shall have more time and will get down to this job. We have fitted the engine ref. counter to our car therefore we can give you exact | ||