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).
Bentley oil consumption tests with various piston ring arrangements.
| Identifier | ExFiles\Box 132\4\ scan0102 | |
| Date | 19th October 1937 | |
| -10- Fig. VII shows the results of tests with various ring arrangements, curve (1) now represents our recently standardised arrangement of rings and curve (4) is a repeat curve. Curve (5) shows the result with rings designed for us to American proportions but centrifugally cast and not cast by the individual method, which is the normal American practice. Curve (6) is test identical with (5) except that rings were cast by the individual method. Both these rings were supplied to us by Light Production Co., and were copied from the Chevrolet rings. The wall pressure of these rings was extremely high compared with our normal practice and from the result of curve (6) appear to be on border line of seizure. Curve (9) shows result of rings to American proportions supplied by Hepworth and Grandage and cast by the individual method. Under full throttle conditions the high pressure rings do not appear to be much better than the standard rings, they are, however, better for 'over-run' conditions when there is a high depression in the cylinder tending to draw oil past the rings. The American proportion rings on road gave an initial consumption of 1800 miles/gallon, unfortunately the unit these rings were in had to be removed from the chassis, but at least the test had shown that 'over-run' conditions have a marked effect on consumption. [Blueprint Section] FIG. VII BENTLEY OIL CONSUMPTION TESTS. AEROLITE 'M' TYPE PISTONS, MOBILOIL 'ARCTIC' OIL, PRESS 38 LB/SQ.IN. R.P.M = 4000 OIL VISCOSITY :- 48.5 SECS. REDWOOD No I SCALE AT 100°C. 2500 " " " " " " " 0°C. Y-Axis: OIL CONSUMPTION (PTS/HR) X-Axis: HRS: RUN. Graph Annotations: RINGS SEIZED EXH: VALVE FAILED. Curve Legend: ① E.60820 COMP. RINGS, 37.2 LB/SQ.IN. SCRAPER RINGS. ② AS ① BUT WITH BEVELLED TOP COMP. RING ③ REPEAT OF ② ④ REPEAT OF ① ⑤ RINGS TO AMERICAN PROPORTIONS (CENTRI-CAST) ⑥ AS ⑤ BUT RINGS INDIVIDUALLY CAST ⑦ REPEAT CURVE OF ① ④ ⑧ AS ① BUT WITH E.60821 SCRAPER RING ⑨ RINGS TO AMERICAN PROPORTION INDIVIDUALLY CAST (HEPOLITE) Stamp: MTHS{Reg Matthews} 5.1.37 | ||