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).
Test results of running Kestrel single and six-cylinder units with Helmore treated oils.
| Identifier | ExFiles\Box 54\4\ Scan096 | |
| Date | 2nd August 1933 | |
| FOR FILES. r 46859 Hs {Lord Ernest Hives - Chair} /Rvce.2.8.33. x2465. r4686. HELMORE TREATED OILS RUN ON THE KESTREL SINGLE CYLINDER AND SIX CYLINDER UNITS. Helmore treatment consists in the addition of some form of lead and either tin or zinc oxide in some small proportion to a lubricant. Running with these oils extending over a period of seven months has been carried out on the single cylinder and six cylinder Kestrel units. RESULTS OBTAINED. It is difficult to say whether there is any improvement with these oils because there is very little trouble with the untreated oils. The following points have however been noted :- (1) On the single cylinder unit bad scoring of the piston skirt occurred when running with treated P.4 which was cured by running with untreated P.2. The running conditions were as follows in both cases - RPM. 2750. MEP. 200 Glycol out: 150°C. Oil Inlet 80°C. (2) On the six cylinder unit, using treated P.4, lead separated out from the lead bronze centre main bearing in a similar manner to that sometimes experienced on main engines. (3) Seventy four hours running has been carried out on the single cylinder unit using treated Castrol R. {Sir Henry Royce} under varying conditions of running up to - 2750 RPM. + 3 lbs. boost. 120°C. coolant outlet. 80°C. oil inlet. Ringside clearance 0.015", 0.013", 0.010". At the end of this period the gudgeon pin was not unduly tight, the rings were only just beginning to show signs of gumming and the piston was practically free from carbon deposits. (4) When using treated P.4 it was found that the added contents changed after a comparatively short period of running, as follows. New Oil. Used Oil. Oil from filter base. Lead-grams/gall. 1.39 0.46 1.26 Tin- " 0.22 0.36 0.55 A sample of carbon taken from under the piston crown was found to contain 25% lead. | ||