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).
The testing and analysis of aluminium piston seizure in an engine.
| Identifier | ExFiles\Box 77\3\ scan0019 | |
| Date | 1st November 1919 | |
| Contd. -3- given these pistons a tremendously more severe test than they could ever possibly get in use on the car. One could never imagine an engine on a car running for more than 5 or 10 minutes full power at 2000 revs. without luffing up. We have never tested any type of aluminium piston on a car engine so severely. One can hardly imagine that failure of lubrication is the cause, because in that case the split band with the small clearance should have been the first to seize. From all the information we have been able to collect, we consider that the seizure started on the top band of the piston. The other four pistons^z on the engine which had run under exactly similar conditions as the two which seized, look in excellent condition with the exception of the top band above the rings. We replaced the two pistons which had seized on the engine by two more identical pistons, except that we gave them more clearance on the top band. We also gave more clearance on the four pistons which had been running on the engine, on the top band. Since then we have run the engine for a further 25 hours at 2000 R.P.M. and have had no trouble. The appearance of the pistons after this run is quite satisfactory. We have marked the place on the top band of the piston which we are sending to Mr. Royce, which shews the appearance we get before the seizure takes place. One point which we think undoubtedly helps in this trouble is the fact that high compression pistons project into the counter bore of the cylinder .125". It is noticeable that on pistons which run in the counter bore, there is a marked line where the aluminium is scored. Contd. | ||