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).
Summary of tests comparing standard, superheated, and water-heated hot spot systems on engines.
| Identifier | ExFiles\Box 66a\1\ scan0102 | |
| Date | 2nd February 1926 guessed | |
| contd :- -17- in France was fitted with a water heated hot spot and this car was found to suffer more from piston knocks after its test than any of the previous cars equipped with standard hot spots. SUMMARY. WARMING UP FROM COLD :- The following, from results of tests and general obser-vations, is the order of merit for warming up from cold :- (1) Standard exhaust heated system. (2) Superheated system. (3) Water " " Of course with increased boiler heating surface we should expect increased rate of heating and could probably make it even quicker in action than the standard. HEAT ADDED TO COOLING SYSTEM. With the boiler heating surface used (75.4 sq.in.) heat is added to the cooling system under full load conditions. The max. value we recorded was 6 1/2% of the heat given to the water by the cylinders. A larger boiler would of course increase this. HOT SPOT EFFECT ON POWER AND EFFICIENCY. The maximum power obtainable at any speed is substantially the same for each system. Better distribution is obtained with the standard and is shown by the wider range of mixture strengths giving smooth oper-ation, consequently greater efficiency can be obtained as indi-cated by the curves. EFFECT ON DETONATION. We cannot detect any difference in detonation whichever system is used. contd :- | ||