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).
Data table and analysis of intake manifold depression and total boost at various engine speeds for different compression ratios.
| Identifier | ExFiles\Box 140\1\ scan0210 | |
| Date | 28th March 1938 guessed | |
| -6- TABLE I. Intake Manifold Depression And Total Boost When A Manifold Pressure Of 10 Inches Of Mercury Above Atmospheric Was Maintained At All Speeds. | Engine Speed, R.P.M. | Intake Manifold Depression, Inches of Mercury (5.55 to 1 Compression Ratio.) | Intake Manifold Depression, Inches of Mercury (4.25 to 1 Compression Ratio.) | Total Boost, Inches of Mercury (5.55 to 1 Compression Ratio) | Total Boost, Inches of Mercury (4.25 to 1 Compression Ratio) | |---|---|---|---|---| | 500 | 0.17 | 0.17 | 10.17 | 10.17 | | 1000 | 0.50 | 0.45 | 10.50 | 10.45 | | 1500 | 0.90 | 0.90 | 10.90 | 10.90 | | 2000 | 1.40 | 1.40 | 11.40 | 11.40 | | 2500 | 2.00 | 1.85 | 12.00 | 11.85 | | 3000 | 2.60 | 2.45 | 12.60 | 12.45 | | 3500 | 3.20 | 2.80 | 13.20 | 12.80 | | 4000 | 3.50 | -- | 13.50 | -- | Figures 12 shows the power output and specific fuel consumption of the standard engine both unsupercharged and supercharged to an intake manifold pressure of 10 inches of mercury above atmospheric at various speeds. Also shown on this curve sheet are the power output and specific fuel consumption of the 4.25 to 1 compression ratio engine supercharged to an intake manifold pressure of 10 inches of mercury above atmospheric. These data were obtained at maximum power air-fuel ratio and maximum power spark advance. The same fuel of approximately 78 octane number was required for the 4.25 to 1 compression ratio with supercharging as for the standard compression ratio of 5.55 without boost, yet the power output with boost was 63 percent greater. The 5.55 to 1 compression ratio with boost, requiring approximately a 90 octane number fuel, showed a power increase of 96 percent over the engine unsupercharged with the same compression ratio. These data serve as a guide to the maximum performance which could be expected from this engine, if it were converted to a supercharged unit and operated at the above manifold pressure. | ||