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).
Comparison of standard and Aerolite pistons regarding oil consumption, power output, weight, and criticisms.
| Identifier | ExFiles\Box 87\2\ scan0141 | |
| Date | 28th February 1936 | |
| -2- Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}12/KW.28.2.36. (2) Improved Oil Consumption. Attached is a list of six 10,000 miles tests on standard pistons and four on Aerolite pistons. Taking the oil consumption at the completion of the tests, when in the ordinary way we might begin to look for complaints from the customer, it will be seen that the standard piston gives a figure of just over 800 miles to the gallon, the Aerolite piston just under 1,600 miles to the gallon. This figure has been consistently confirmed in over 800 hours' high speed endurance test bed running. (3) Improved Power Output & Mechanical Efficiency. The Aerolite piston gives at least 5% improvement in power output, and in some cases as much as 8%. When it is considered that 8% is half as much as the difference between the small and the large bore Bentley, it cannot be regarded as insignificant. We do not expect the figures on production to agree exactly with our experimental results because production engines are new and experimental figures are obtained on units that are fully run in. However, comparing 12 production engines with R.R. pistons with 12 having Aerolite pistons, the figures obtained show a gain of 8% at 1500 revs., 4% at 3000 revs., and 1% at maximum speed. (4) Weight. On the big bore engine the fully split piston weighs 20 1/4 ozs. and the Aerolite 18 1/2 ozs. It is only fair to admit that the reverse was the case on the small bore engine. We understand that the following criticisms have been levelled at the Aerolite piston :- (1) It is bad for oil consumption - Sg.{Arthur F. Sidgreaves - MD}9/E.4.2.36. We have been in communication with Hd.{Mr Hayward/Mr Huddy}, Kingsbury and Paris, and in no single case has high oil consumption in service been traceable to Aerolite pistons. In four cases, however, has it been found necessary to change the standard pistons because of the high oil consumption. | ||