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 discussing engine oil consumption, smoking exhaust, and the effect of engine speed on these issues.
| Identifier | ExFiles\Box 178\1\ img147 | |
| Date | 19th May 1926 | |
| - 15 - to the much lower flame temperature with large exhaust dilution being unable to cause complete combustion of the oil and resulting in a smoking exhaust which is not evident with high flame temperatures as at full throttle. Apart from the oil passing the rings we experienced smoking exhaust when running light before the oil holes in the end of the inlet rockers were plugged. This was caused by free clearance between the valve stems and guides which allowed oil to be sucked down the stems into the induction pipe. Similar trouble is experienced if the exhaust guides are slack which permits oil to run down at low speeds or when the engine stops. EFFECT OF ENGINE SPEED. The oil consumption is found to increase as the speed of the engine increases. Part of this increase will be due to the increase in flow through the bearings resulting from the centrifugal pressure on the oil and the remainder due to the increased piston speed. The consumption curves given for the car were taken at an average speed from 30 to 35 M.P.H. but with increased road speed we should expect the consumption to be greater. contd. | ||