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).
Tests and recommendations for modifying a cooling system to reduce pressure and prevent flow reversal.
| Identifier | ExFiles\Box 178\4\ img021 | |
| Date | 11th April 1932 | |
| -3- TEST RESULTS. The foregoing schemes are satisfactory in that cyl block pressures are effectually reduced and thereby minimising the risk of a reversal of flow. IMPORTANT. Apart from the restriction set up in the carburetter jacket main passages the restriction in the front guard and interconnections of the unit is considerable (with the standard fittings). The fact of increasing the dia of the pipe from 1.25" to 1.50" reduced the cyl block pressure to 1.6/sq.in. The dia of the ports in the cyl jackets is 1.5". It will be seen that the pipes leading from them should be as large as possible. In addition, the end of a pipe which goes into the block or should have small radii to reduce the dead end effect and therefore maintain a full size. (see sketch) when water is passing thro'. This applies to all plain types of joints where the pipe diameters are cut down to the minimum. The fitting of the 1" pipes reduces the pressures in the cyl blocks by 3. lbs/sq.in. The total reduction with all the modifications as tested and described being 4.3 lbs/sq.in. A test was carried out using only one 1" pipe from the front. The pipe tapped the highest point of the front branch. This was to try and simplify the modifications and reduce the number of pipes. This was not effective and violent reversals being experienced. RECOMMENDATIONS:- The fitting of extra pipes to alleviate the high jacket pressures are inevitable until such time as the carb jackets are cleared up to reduce restriction. It is not possible to tap the cyl jackets between Nos. 3 and 4 as on the supercharged engine system. The modifications do not affect major units on the engine (which are on spl blocks) and therefore should be easily accomplished on existing pipes and the extra pipes easily and neatly arranged without making the engine appear untidy looking. As it is probable that the new cars will shortly supersede the present type we recommend that the modifications should be applied to the old cars system on engines that may be required for evap cooling so as to have one standard of modifications only. | ||