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).
Research program report on engine performance using dynamometer tests, different compression ratios, and supercharging.
| Identifier | ExFiles\Box 140\1\ scan0206 | |
| Date | 28th March 1938 guessed | |
| -2- on engine performance are available to designers. The Ethyl Gasoline Corporation instituted a research program designed to yield such data. The first phase of the work consisted of dynamometer tests on an eight cylinder engine with the air *air supplied by a separately driven compressor. The next phase includes a group of dynamometer tests with a supercharger connected to and driven by the engine. The third phase consists of tests on the road, the supercharger being driven by the engine. Two compression ratios were used for the tests in the first phase of the program, a low ratio of 4.25 to 1 and the standard ratio of 5.55 to 1. The lower ratio of 4.25 to 1, supercharged to an intake manifold pressure of 10 inches of mercury above atmospheric, was selected because with three fuels of different octane numbers the speeds of incipient detonation were the same as for the engine with 5.55 to 1 compression ratio unsupercharged. The lower compression ratio was obtained by placing a special copper gasket of the proper thickness under the standard cylinder head of the engine. The initial phase of the test program was divided into two sections. The first included a series of full throttle runs of the standard engine over the speed range between 500 and 4000 revolutions per minute. This section also included groups of runs at the standard compression ratio of 5.55 to 1 and at the lower ratio of 4.25 to 1 with a constant intake manifold pressure of 10 inches of mercury above atmospheric. The tests of the second section were made at a constant speed of 1000 revolutions per minute with the 5.55 and 4.25 to 1 compression ratios and intake manifold pressures between 0 and 30 inches of mercury above atmospheric. The test equipment used for a fundamental investigation of any problem must be selected and assembled so as many as possible of the variables can be controlled. Since supercharges driven by the engine in the conventional manner do not lend themselves to simple methods for maintaining either a constant discharge pressure with a wide range in quantity of air handled, or a constant volume of air delivered over a wide range of discharge pressures, a separately-driven compressor was used to supply the supercharging air for these tests. Furthermore, the nature of the program, a fundamental investigation of the effect of supercharging, suggested that the air should be supplied by a separately driven compressor. This permitted a greater freedom in the control of the variables with a corresponding degree of constancy that could not have been obtained by any other method. Sufficient test data were obtained so the calculations of power required by the supercharger could be made with a certain measure of reliability. Thus the data can be made applicable to commercial installations. | ||