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).
Report comparing the detonation characteristics and Mean Effective Pressure (M.E.P.) of aluminium versus cast iron cylinder heads.
| Identifier | ExFiles\Box 86\1\ scan0055 | |
| Date | 10th March 1934 guessed | |
| -2- With regard to detonation, we found that on both heads the point where audible detonation ceases is approximately the same in relation to spark position from T.D.C. The aluminium head allows about 2° more advance than the cast iron head but this is such a small difference and what with the difficulty in determining the position where detonation ceases on the bed due to other noises we can only say that both heads are about the same in this respect. The aluminium head therefore shows a higher M.E.P. at the point where detonation ceases than the cast iron head but this is not, from our tests, due to the difference in material, but due to the fact that the aluminium head has a higher M.E.P. in the first place due to reasons (1) and (2). The governing factor appears to be the ignition advance more than the material from which the head is made. R.{Sir Henry Royce} Matthews. | ||