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).
Proposal to abandon the oil cooler on Phantom III engines, based on tests conducted at Brooklands Track.
| Identifier | ExFiles\Box 107\2\ scan0133 | |
| Date | 25th May 1938 | |
| Rm{William Robotham - Chief Engineer}/Std.2/HH.25.5.38. PROPOSAL TO ABANDON OIL COOLER ON PH.III ENGINES. In connection with above proposal we recently carried out tests at Brooklands Track with a Ph.III car (35-EX) fitted with latest type standard big end and main bearings (forked rod bearings in AC.6 and blade rod and main bearings in Whitemetal). The tests consisted of running the car continuously at maximum speeds under different sets of conditions (direct drive, overdrive, oil cooler fitted, no oil cooler fitted etc.) until the oil temperature reached a steady figure. Tests were also made at a cruising speed of 80 m.p.h. Tests were made generally with a water temperature of 95-100°C in order to reproduce as far as possible the worst conditions likely to be met, i.e. high atmospheric temperatures. Tests were also made to determine the effect on oil temperatures of alteration in water temperatures. Results of tests are shown in sheet (1) attached. Conclusions from Tests. Comparison of tests I and III and of II and IV indicate that the oil cooler drops the ultimate oil temperature at inlet to bearings by 16-20°C approximately (this includes correction for water temperatures). Tests III and IV indicate that the ultimate oil temperatures obtainable (at inlet to bearings) without oil cooler fitted are 126°C and 138°C on the overdrive and direct gears respectively - however, these will be increased by 4°C (as mentioned below) in very hot weather. Tests III and IV also indicate that the oil cooler can be dispensed with on engines fitted with AC.6 big end bearings (i.e. fitted up as 35-EX car was tested) since an endurance run has been successfully run on the test bed with an oil inlet (to bearings) temperature of 130°C which temperature is barely reached in overdrive and is only exceeded on the direct gear after continuous maximum speed driving for upwards of 20 miles. | ||