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).
Analysis of engine issues including increased oil consumption and low power output following a 60-hour endurance test.
| Identifier | ExFiles\Box 3\6\ 06-page194 | |
| Date | 11th June 1934 | |
| -2- He/7JH.2/KW.11.6.34. The oil filter and crankcase lower half were examined at 50 hrs, but no sign of bearing metal was found. The unit was stripped and examined at the completion of the 60 hours. For particulars of the condition of the unit see H1C.11/BR.6.6.34. The increase in the rate of oil consumption is very probably due to the gumming up of the top piston rings. The gumming up of the rings may increase consumption in two ways - (a) by allowing more oil to work past the piston to the combustion chamber, (b) by the increased gas leakage past the pistons carrying more oil in suspension into the air silencer and carburetter intakes. The latter method would appear to be the more likely one. That a large amount of oil is carried away by the blow past gases is proved by the fact that during the last 4 hours of the endurance run when no air silencer was fitted two hours running was sufficient to smother the whole test bed with a film of oil. It is doubtful whether the gumming up of the rings will explain the comparatively low power output. At high speeds gas leakage past the pistons has very little effect upon the power output. The most probable explanation of the low output is bad oil film conditions between the pistons and cylinder walls due to the poor bedding of the pistons and consequent high piston friction. He/P.J.Hardy. | ||