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).
Modification to the 'Aerolite' piston crown to raise the compression ratio.
| Identifier | ExFiles\Box 147\3\ scan0181 | |
| Date | 28th November 1938 | |
| Mr. Walker. Rm{William Robotham - Chief Engineer}/CTS{C. Trot Salt - Carburation}2/R.28.11.38. PISTONS. The drawing Rm.{William Robotham - Chief Engineer}522 shows a modification to the crown of the "Aerolite" piston, produced and supplied by the Light Production Co. Ltd. The purpose of this alteration to the crown of the piston; is to raise the compression ratio, but the following points are of interest, and make it desirable to apply for a patent. The shape of the raised portion of the crown, conforms to the shape of the combustion chamber of the cylinder head in such a way as to enter the combustion space, as the piston reaches the top of its stroke. We believe the effect of this is to delay the burning of the gas which exists over the remaining area of the piston crown. There is certainly a marked effect on the degree of detonation usually associated with the increased compression ratio. It will undoubtedly be desirable to further vary the shape of this piston crown, and the variations to which we attach most importance are:- (a) Actual depth of the raised portion. (b) Annular area between the raised portion and the lip of the combustion chamber, when the piston is at the top of its stroke. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} | ||