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).
Fuel leakage, fuel line capacity, and methods for inducing rotational air swirl in an engine.
| Identifier | ExFiles\Box 133\3\ scan0043 | |
| Date | 28th February 1939 | |
| -4- A difficulty experienced with the differential type of valve is fuel leakage, which has a similar effect to using a smaller pump plunger size, giving a slight power drop. Fuel Line Capacity. A decrease in fuel line dimensions from .118" dia. x 36" long to .062" dia. x 22" long, improves the power by 4.4 lbs/sq.in. due presumably to the quicker rate of injection. A small fuel line capacity helps starting and idling in that if the capacity is large and high injection pressures are used, it is possible to pump the minute quantity of fuel required for one injection at idling into the fuel line without raising the pressure sufficiently to open the valve. This is done only on the next stroke of the pump, when a double charge is injected giving eight-stroking and excessive pressure. We consider especial attention should be paid to this point on the Diesel Bentley as fuel quantities will be much smaller on this single cylinder unit. Rotational Air Swirl. Four methods of inducing swirl have been tried, viz:- (a) Masks around inlet valves inside the head, positioned to promote swirl. This scheme is about the best as a moderate swirl is induced, whilst still maintaining a volumetric effy. of 82%. A power curve showed 86 BMEP at 2200 R.P.M. and 110 BMEP at 1000 R.P.M. (b) Diagonally opposed inlet valves, made possible by special camshafts, give only a relatively slight swirl, which can be improved by fitting deflectors on the induction ports. A great deal of work was not done on this arrangement, but power appeared to be down on other arrangements. Continued. | ||