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).
Continuation of notes on engine nozzles, shrouded valves, fuel pumps, and superchargers.
| Identifier | ExFiles\Box 134\1\ scan0145 | |
| Date | 18th March 1939 | |
| -2- Da{Bernard Day - Chassis Design}/AM.1/N.18.3.39 Cont'd.{John DeLooze - Company Secretary} ------------------- 'burr' raised on it if carelessly handled on the bench. This type of nozzle can be used in air-cell engines (Ricardo-Comet, Lanova, and M.A.N.) but the angle of spray is not obtuse enough to make it suitable for direct injection heads. Shrouded inlet valves must be used in direct injection designs. These reduce the breathing capacity of the engine and also increase the tendency towards sticking inlet valves due to carbon formation between the shroud and the port throat. It is not uncommon to find evidence of this on the piston crowns although serious mechanical failures are rare. In Mr.Blea's opinion the Bosch fuel pump is not very suitable for a variable speed engine due to its varying volumetric efficiency. Trouble is experienced at high rotational speeds with tappet bounce due to the very heavy reciprocating parts. Air-locking is also liable to occur at high speeds due to some effect caused by the discharge of high pressure oil to the inlet side of the pump at plunger cut-off. The National Co. have had very encouraging results with Buchi exhaust turbo driven centrifugal superchargers. The power output has been increased 50% for an exhaust gas temperature rise of 100°Fah. and a cylinder pressure increase of about 50 lb/in². No bye-pass air cooling of the turbine rotor is necessary. They are now experimenting with a high pressure gas engine using spark ignition or alternatively oil injection ignition, the oil injected being in the nature of a pilot charge of small quantity. Da{Bernard Day - Chassis Design}/AM. | ||