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).
Comparison of engine start times and torques using old and new ranges of oil under hot and cold conditions.
| Identifier | ExFiles\Box 145\3\ scan0256 | |
| Date | 18th February 1937 guessed | |
| - 3 - There is nothing in the figures to indicate that any property of the oil other than viscosity is connected with startability. Old range Time to start. New range Time to start. Old Single. 2 secs. New Single 0 secs. Old Double 18 " New Double 7 " Old Triple 22 " New Triple 13 " Old Aero. 25 " New Aero. 18 " It will be observed that in each instance the time to start is less with the new oils than the old. (4) Static and "Just moving" Torques. These were measured with a spring balance on the starting handle and each reading is the average of a large number. They were measured both hot and cold. Static Torques, hot and cold. Old range. Hot lbs.ft. Cold lbs.ft. New range. Hot lbs.ft. Cold lbs.ft. Old Single 11.4 9.2 New Single 6.3 6.4 Old Double 9.9 7.9 New Double 5.9 7.0 Old Triple 8.8 6.6 New Triple 6.2 6.2 Old Aero 7.8 6.0 New Aero 6.5 6.1 It is interesting to note that on the old range the hot static torque is noticeably higher than the cold static torque, and further that it decreases with increasing viscosity. On the new range the static torque is practically constant, hot or cold, low or high viscosity. "Just moving" torques, hot and cold. Old range Hot Cold New range. Hot. Cold Old Single 8.6 6.3 New Single 6.3 6.4 Old Double 8.3 4.2 New Double 5.9 7.0 Old Triple 7.0 4.4 New Triple 6.2 6.2 Old Aero. 7.3 4.4 New Aero 6.5 4.2 We had hitherto considered the "just moving" torque to be constant at all temperatures and with all oils. It does appear from these results that with the old range of oils there is some slight variation between oils and a bigger variation between the hot and cold states. On the new range there is very little variation except for cold new Aero Shell which is similar to the old Aero. The fact that the engine is very new (less than 50 miles on the road) may account for the difference between hot and cold "just moving" torques; it may be that the hot clearances are very small indeed. Comparison of static and "Just moving" torques, cold. Old range Static. Just moving New range. Static. Just moving. Old Single. 9.2 6.3 New Single 6.4 6.4 Old Double 7.9 4.2 New Double 7.0 7.0 Old Triple 6.6 4.4 New Triple 6.2 6.2 Old Aero. 6.0 4.4 New Aero. 6.1 4.2 | ||