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).
Engine performance tests, comparing different compression ratios and analysing power output, frictional losses and detonation.
| Identifier | ExFiles\Box 6\7\ 07-page008 | |
| Date | 1st May 1926 guessed | |
| contd :- -2- We have appended curves which shew both the power output with the high ratio and the present standard (sheet 1) and in addition a third curve is plotted giving the brake horse power calculated for a 5.45 ratio based on the actual indicated power given with the standard 4.75 ratio. This assumes that the increase of power is proportional to the air standard efficiency, which assumption we, and other investigators, have found to be quite reliable in practice. The small discrepancy between the actual and theoretical could reasonably be accounted for by slight difference in the frictional losses of the two sets of pistons tried as we have previously observed differences of this magnitude with different standard pistons and those in question were on the 'free' side having been 'eased off' after the first run. Throughout the tests the engine ran perfectly well and the results were sufficient to shew us that the expected power could be obtained without such factors as detonation or pre-ignition being manifest to such a degree as to reduce the possible power output. Audible detonation is not entirely absent but what extent this is worse than on the standard engine is difficult to express - particularly so on the test bench engine. We are satisfied that detonation to the extent we experience it has no appreciable detrimental effect on the functioning of the engine and as its presence is more of a psychological than a physical disadvantage it remains to obtain the opinion of drivers as to whether it is more evident than usual and if so, does it outweigh the other benefits derived. contd :- | ||