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 factors affecting engine cooling, including the influence of combustion chamber design.
| Identifier | ExFiles\Box 178\1\ img020 | |
| Date | 15th February 1926 guessed | |
| - 4 - full throttle conditions only. While the heat dissipating capacity of a radiator can be predicted with very fair accuracy, the heat imparted to a cooling system by the power unit varies widely and is affected by a number of factors. It is for this reason that the performance of cars of similar displacement with similar radiator dimensions may differ to a very large extent. The amount of heat imparted to the cool-ing water per road wheel H P generated, is not constant throughout the whole range of engine speeds. It is invariably greater at 'low engine speeds as will be seen from the following graphs. An engine with a good low speed torque suffers therefore from an inherent disadvantage with regard to over-heating in this respect. Compression ratio, displacement, design of combustion chamber, and tendency to detonate all have a marked influence on the heat imparted to the cooling water. The relative significance of these items will be seen from the following details. (b) Influence of combustion chamber design. The more compact a combustion chamber, the less heat is likely to be imparted to the cooling water, other things being equal. It follows therefore that as a general rule it may be said that the normal 'L' head engine will give a larger quantity of heat to the cooling system than the over-head valve.engine while possibly developing considerably less B.HP. The appended graph shews the waste heat which has to be catered for in three engines at approximately the same dimensions. The 40/50 RR. is an 'L' head engine and while developing some 30% contd. | ||