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).
Performance report for a small Compression Ignition (C.I.) engine unit.
| Identifier | ExFiles\Box 133\3\ scan0034 | |
| Date | 25th February 1939 | |
| Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards}2/MH.{M. Huckerby}25.2.39. RUNNING ON SMALL C.I. UNIT. (6.000 BORE x 6.600 STROKE) Description of Engine. C.R. - 14.3; Length of conn. rod - 13.258". Bosch fuel injection. Airship Diesel Fuel oil, Sp.{Mr Spinney} Gr.{George Ratcliffe} .846. Valve timing for max. performance:- I.O. 17°L; I.C. 38°L; E.O. 49°E; E.C. 9°L. Maximum cylinder pressure 1000 lbs/sq.in. Injection pressure 4000 lbs/sq.in. with R.A.E. nozzle, 7 holes, .015" diam., 120° core. Performance. The maximum power was 121.5 I.M.E.P. (81.5 B.M.E.P) at 1950 R.P.M., giving a volumetric efficiency of 89%. Power was reduced some on M.E.P. by reducing the maximum pressure from 1000 lbs/sq.in. to 800 lbs/sq.in. Valve Timing. Overlap appears to have very little effect on power output, a 30° drop in inlet duration giving no appreciable change in power output, though the overlap was altered by this change from 26° to -8°. Compression Ratio. Performance appeared slightly better for a C.R. of 14.3 than for 12.5. No actual figures can be quoted however. Piston Crown Shape. A conical topped piston with a central injector gave a rather better power output than a hollow design of piston, nozzles being adjusted in each case to give the maximum power for that particular arrangement. | ||