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).
Test results document discussing gross power output, fuel economy, and the effects of supercharging on intake manifold pressures.
| Identifier | ExFiles\Box 140\1\ scan0209 | |
| Date | 28th March 1938 guessed | |
| -5- The optical pyrometer used to measure the exhaust valve temperature is shown in Figure 11. Also shown in this photograph is the thermocouple in the exhaust manifold just below the quartz window, for measuring the exhaust gas temperature. This was a chromel-alumel thermocouple which was connected to an indicating pyrometer. Back of the optical pyrometer will be seen a thermometer which was inserted in the intake manifold at the head of the branch to numbers 1 and 2 cylinders for measuring the mixture temperature. TEST RESULTS. GROSS POWER OUTPUT AND FUEL ECONOMY. In the analysis of these engine data, it should be remembered that the intake manifold depressions of the unsupercharged engine at full throttle varied with engine speed as shown in Table I. Therefore the actual effective boost on the engine when it was supercharged at any given speed was equal to the sum of the amount by which the intake manifold pressure exceeded atmospheric (ten inches of mercury) and the corresponding manifold depression for the engine when it was operated unsupercharged at full throttle at the same speed. Thus at 4000 r.p.m. the boost on the engine with 5.55 to 1 compression ratio, when supercharged to an intake manifold pressure of 10 inches of mercury above atmospheric, was 13.5 inches of mercury. No reason is known for the differences in intake manifold vacuum which were observed for the two compression ratios at the higher speeds. It seems most probable that they were caused by differences in atmospheric conditions or by slight changes in engine conditions, since these data were not all taken on the same day. | ||