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 testing stages, analyzing oil consumption with different piston rings and lubrication setups.
| Identifier | ExFiles\Box 148\1\ scan0212 | |
| Date | 27th November 1939 | |
| -2- The second stage of the tests were run with high main oil pressure and increased bearing flow. To obtain this a large capacity oil pump was used and a stronger relief valve spring fitted which gave 50 lbs.sq.in at 4000 engine r.p.m. yet by-passed sufficient oil to feed the engine gears and rocker shaft. The big end bearings were grooved and two .046 inches diameter holes were drilled in each connecting rod thereby giving increased bearing flow and consequently increased cylinder bore lubrication. Before each series of tests, the engine was "run in" for five hours and given one hour at 4000 r.p.m. full throttle to allow the new piston rings which were fitted for each test, to "bed in" correctly. Oil consumptions were then taken at 4000 r.p.m. full throttle, until a stable figure was obtained. A gasmeter was used to record crankcase blowby. Tests 1 and 2 were run with a main oil pressure of 36 lbs. sq.in. and standard cylinder lubrication. The result gave curves 1 and 2 which show the advantage of using "Celloten" rings against standard non plated rings. Tests 3, 4 and 5 were run under second stage conditions namely increased cylinder bore lubrication. An interesting peculiarity is shown by curves 2 and 3. One would expect the oil consumptions to be greater on test 3 than tests -, as the former were run with increased cylinder lubrication. As a new cylinder block and new piston rings were used for each of these tests it proves our previous experience, that consumption figures are inconsistent even when using new piston rings and new cylinder blocks of the same type. Curve 5 gives no useful information for this series of tests, as it was found when dismantling the engine that the piston rings were the wrong type having .020 inches side clearance. It is included, however, to show that as the ring side clearance is increased, the oil consumption also increases. The conclusion of these tests is clearly shown by the curves. An analysis being that the Hepworth and Grandage 'L' section high pressure rings are inferior to the "Celloten L" section normal pressure rings for keeping down oil consumption and it is natural to suppose for cylinder bore wear, considering the greater diametral load on the cylinder bores. | ||