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).
Bench tests of a six-cylinder petrol engine with Wellworthy high compression pistons.
| Identifier | ExFiles\Box 148\1\ scan0208 | |
| Date | 13th September 1939 guessed | |
| 1256. File Pistons general. RESEARCH ENGINEER. TO: CHIEF ENGINEER. Report on tests with Wellworthy High Compression Pistons in the 3.1/2" x 5" Six-cyl.Petrol Engine. A series of bench tests have been carried out on a 3.1/2" x 5" six-cylinder petrol engine to determine whether the performance of the engine could be improved by fitting a set of high compression pistons designed in such a manner that a protrusion on the piston crown fitted snugly into the combustion chamber in the cylinder head, therefore both raising the compression and providing a certain amount of squish turbulence. Analysis of test results obtained: In the first place the engine was check tested in its standard condition and a basic performance curve established. Subsequent to this a set of the modified pistons was fitted, these pistons had a compression ratio of 7.56 : 1, and the performance results obtained from these pistons indicate that the power and fuel consumption of the engine are only altered to a very minor degree. Ignition is extremely sensitive and over advance causes excessive detonation and engine roughness. At the conclusion of this test it was considered that the compression ratio of 7.56 : 1 was much too high for this engine, and further experiments were then conducted with the compression ratio reduced to 7 : 1, and finally to 6.75 : 1. The reduction in compression ratio was effected by machining off a portion of the protuberance in the piston crown. The full series of performance results which are | ||