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).
Horsepower required for a Phantom II to achieve 100 M.P.H. and comparing engine performance with a Bentley.
| Identifier | ExFiles\Box 182\M19\ img194 | |
| Date | 8th June 1931 | |
| ORIGINAL To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}7/KT.8.6.31. x7771. H.P. REQUIRED ON P.II. TO ACCOMPLISH 100 M.P.H. With reference to E4/M2.6.31. we think that undoubtedly the best method of getting the figures you require, is to put our engine giving 180 BHP in the Continental car and run it on the track. At the same time we can place fixed restrictions in the carburetter which will reduce the H.P. by a known amount and so obtain a fairly accurate idea of the tractive resistance curve of the complete car. In our experience, extrapolation of tractive resistance curves is rather unreliable because there is no doubt that on a normal type of body, the resistance is not a constant power of the road speed. Some of our curves shew that there is a critical speed where the air flow appears to become turbulent, and the tractive resistance rises correspondingly rapidly. There is no doubt that the Bentley must have obtained an excellent power output with their 8-litre engine to run at the speeds they do, but there is certainly nothing mysterious about what they have done that we cannot approach with the same compression ratio, provided we accept their standard of slow running. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||