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 oil consumption and 'blow-by' with comparisons between different piston ring types and valve stem designs.
| Identifier | ExFiles\Box 144\3\ scan0319 | |
| Date | 18th March 1939 | |
| 1220 COPY FOR FILES. H Rm.{William Robotham - Chief Engineer} To Rm.{William Robotham - Chief Engineer} Typed. 18.3.39. OIL CONSUMPTION & "BLOW-BY". Herewith replies to your questions concerning the above as far as our records permit. (1) Blow-by with pinned rings ? Figures have been obtained for the above on a 25/30 unit, the pistons having 3 compression rings and 1 scraper. A direct comparison was obtained on similar pistons but without the stops the rings being free to rotate. The result taken at 4000 r.p.m. full throttle shows that there is twice as much "blow by" with pinned rings as compared with "non pinned" rings, although the figure for the former is not excessive. Pinnedrings - "Blow by" 1 cu.ft./min. Back pressure 1.2" H2O Non " " " " .5 " " " " " .8" " (2) Oil Consumption variation with speed. RPM - Pts/hr. 4000 1.5 3000 .8 2000 .25 1000 .076 The above were taken under full throttle conditions. (3) Oil consumption on Buick and what prevention against oil down valve stems. Dodd is going to take a consumption at the first opportunity. There are no seals to prevent oil going down the valve stems but will note the comparison of the oil supply with that of Wraith. The valve guides stand very high, approx. 1.0" above the head. | ||