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).
Page discussing engine compression ratios and their effect on heat transfer to the cooling system, including a graph of test results.
| Identifier | ExFiles\Box 178\1\ img022 | |
| Date | 15th February 1926 guessed | |
| - 6 - (c) Compression ratio. As long as detonation is not incurred thereby, raising the compression ratio of an engine reduces the amount of heat given to the cooling water because the benefit obtained depends largely upon the cylinder head design. Within the practical limits of increase it is not very large. The curves given are those of high and low compression Silver Ghost engines actually obtained on the test bench. They are not altogether satisfactory however. We should say that if the compression ratio of an engine was increased from 4 - 1 to 5.5 - 1, the total heat given to the cooling system should decrease by about 6%. Graph III % OF TOTAL HEAT TO COOLING WATER ENGINE R.P.M 3.9-1 4.4-1 (d) Influence of engine dimensions. As a general rule if two engines are identical in design but one is larger than the other, the larger engine will transmit less heat to the cooling water per B.HP. developed than the smaller one. This is because the volume of the combustion space contd. | ||