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).
Factors affecting jacket water boiling and comparing the performance of different car models under various conditions.
| Identifier | ExFiles\Box 24\5\ Scan088 | |
| Date | 18th June 1925 | |
| (COPY) x766 BY2/H.18.6.25. c. Hs.{Lord Ernest Hives - Chair} RE JACKET WATER BOILING. ----------------------- Referring to CJ2/E.16.6.25, and CJ9/E16.6.25, it is misleading to make comparisons of performance so entirely different in essential factors. The question of jacket water boiling if one which cannot be seriously studied where different cars are concerned unless not only have the performances to be compared been produced and over same route, but also at the same time. Dealing with CJ2/E.16.6.25, I should not on the face of the matter with the data put forward, have expected the jacket water to have boiled but one would, whilst accepting the general air temperature as that of the shade, certainly expect to find the air over the track itself in the calm state of atmosphere which existed on Monday to be considerably above 80°C. as the concrete track would be in the full blaze of the sun's rays, and therefore the air above the track itself would, if it had been tested by a thermometer exposed to air but shaded from sun's rays and stationed above the track, have registered considerably more than the general air temperature to which PN.{Mr Northey} refers. There are no available data in regard to jacket water temperature on any of our chassis for speeds above 60 miles per hour, but we do know that the car tried out by PN.{Mr Northey} for speed was heavily handicapped on speed performance and in regard to its jacket water temperature by:- a/- Its low compression engine. b/- Its low geared axle. It has, however, been already shown by the experimental department's reports, that we are not able to run the New PhantomCodename for PHANTOM I engine on full torque when the air temperature exceeds a figure somewhere round 85°F.{Mr Friese} without the jacket water boiling. I thought that as a result of the very full discussion of this subject which recently took place that every-one was aware of the fact that whilst the New PhantomCodename for PHANTOM I engine was somewhat better than the Silver Ghost, it would still boil its jacket water under conditions which demanded the engine being driven on full torque for a considerable time with a high air temperature, either on a flat road at certain critical speeds or hill climbing on gradients demanding full engine torque. -Cont'd- | ||