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 bore wear, comparing oil consumption data for standard and porous castings over mileage.
| Identifier | ExFiles\Box 115\2\ scan0564 | |
| Date | 25th April 1940 | |
| Rm{William Robotham - Chief Engineer} - 3. Serial No.102. OY.3/D/Apr.25.40. Anyhow, the balancing is a final trueing in the flywheel plane only. Bore Wear. (Discussion with Gordon and Byron Ellis). Briefly: Standard gray iron bores of 186-210 Brinell are only fair. Super nickel chrome iron bores costing 4 dollars a car extra, and of 240 Brinell are atrociously bad. Wear 3 to 4 times as fast as gray iron. Porous bore made from castings which should have been rejected for porosity, (Brinell only 146) indicate a use- ful life, three times as great as the "good" gray iron bores. Here are preliminary figures on a first test - Standard "Porous" Castings. Castings. 0 - 5,000 miles 1003 miles/quart 306 miles/quart 5,000 - 10,000 miles 727 " " 422 " " 10,000 - 15,000 miles 342 " " 333 " " 15,000 - 20,000 miles 248 " " 322 " " 20,000 - 25,000 miles 293 " " (10-70 M.P.H. on Hill Route and Track, except first 9,000 miles on standard engine). Further tests on porous bores running parallel with standard, show that initial oil consumption is higher, but that bores improve with use up to 10,000-15,000 miles, just when the standard iron begins to show a sudden increase in oil consump- tion. Ellis is preparing micors. and samples of "porous" bore, and the wear records obtained with these as against standard iron, which are in the ratio of one to three, or better. Ellis denies that these are chance results. Says that all indications have pointed this way for years. Spottiness and "scatter" in earlier bore wear results, ascribed to differences in starting or operating conditions, disappeared as soon as Cadillac obtained reasonably consistent piston rings. | ||