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).
Discrepancies in horsepower from different 'Japan' cylinder heads due to modifications.
| Identifier | ExFiles\Box 103\4\ scan0085 | |
| Date | 16th September 1931 | |
| x5050. To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}2/MJ.16.9.31. Whilst we have been investigating the various peculiarities of the turbulent head in connection with power, we found that we have been getting different HP's under the same conditions from different 'Japan' heads. Further investigations show that two and a half years ago a number of 'Japan' heads were altered to reduce the compression ratio to the following drawing (V.555). We give you this information because we feel that you may have been mislead by comparing Phantom ll head with 'Japan' head, whereas the 'Japan' heads we have been using on the power curves that we have given you have been altered from the original drawing. When we have finished our existing series of experiments, we hope to be able to tell you what this alteration and various others are worth in actual maximum B.H.P. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||