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 page detailing the performance characteristics of an Ante-Chamber engine design.
| Identifier | ExFiles\Box 133\3\ scan0055 | |
| Date | 3rd March 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/Edl/R.3.3.39. Ante-Chamber Design. (a) Fuel consumption worse than on D.I. engine, and is seldom better than .400 lbs/BHP/Hr. (b) The Comet III was relatively insensitive to fuel quality from 40 cetane upwards, and even better results were obtained from the Whirlpool. This latter head, however, was not recommended for use on high speed engines due to excessive thermal stresses where the two holes of the venturi cross each other, causing cracking. (c) Good high speed torque, but power at low speeds was less than with the D.I. combustion chamber. (d) The heat loss to the coolant greater than on the D.I. Unit, comparative figures being 70% for the ante-chamber as against 55-60% for the D.I. (e) Diesel knock was better and maximum pressures lower. (f) Heater plugs essential for starting, though an alternative method of heating the intake air may be adopted. (g) Compression Ratio has got to be somewhat higher - 17-20 ratios. (h) A Comet III engine, opened up to full load - 100 B.M.E.P. @ 2000 R.P.M. - from a tick-over speed showed only a slight puff of smoke, and was completely odourless at the above rating In conjunction with the Comet III head, Ricardo's have developed a new type of cavity in the piston crown consisting of two recesses to match up with the valves between which there is a channel lining up with the venturi. This is a progressive move in that it enables the designer to alter his valve timing to some extent without hitting the piston. It is interesting to compare the view with that of Leyland and A.E.C. who have both discontinued work on the ante-chamber heads in favour of direct injection, the reasons put forward for this change were the poorer fuel con- sumption of the ante-chamber head, the increased heat flow, and the necessity for heater plugs to assist starting. | ||