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).
Technical description of an engine's specifications and performance characteristics.
| Identifier | ExFiles\Box 179b\3\ img168 | |
| Date | 7th February 1933 | |
| -2- There is an insulating space around this neck which tends to keep the temperature of the flame plate constant. The compression ratio is of the order of 16 : 1 and the charge is ignited in the precombustion chamber. The capacity of this chamber is about one quarter of the total volume of the compression space. The first ignition in the small chamber thus only causes combustion of one quarter of the total charge. This suddenly raises the pressure in the chamber and forces the remainder of the charge in to the real compression space, passing through the holes in the flame plate on its way, and thus becoming thoroughly atomised and mixed with the fresh air above the piston. The whole charge is then ignited. The Bosch injection system is used, consisting of two six-plunger fuel pumps, one for each row of cylinders, and 12 spring loaded automatic injectors. The pump block has an idling governor attached. Ball and roller bearings are used throughout. The integral crankshaft is supported by split roller bearings between each pair of adjacent cranks. The valve rockers have 'needle bearings' containing a great number of small diameter rollers. Pump circulation of cooling water and dry sump pressure lubrication are employed. Starting is by compressed air. To facilitate starting, each cylinder is provided with a glow plug. Double reduction gears are used to reduce the engine speed from 1780 r.p.m. to below 1000 r.p.m. propeller speed, the two reduction ratios being 1.5:1 and 1.2:1. The nominal output is 700 BHP. at 1675 r.p.m., and the maximum output 750 BHP. at 1780 r.p.m. The weight of the engine, dry, inclusive of fuel pumps, 200 watt lighting generator, starting air distributor with pipes and fittings, and reduction gearing, but without air bottle, is 2090 lbs., which is equivalent to 2.78 lbs. per BHP. on the basis of maximum output. The results of a propeller test are shown in Fig.4. The maximum B.M.E.P. was 108 lbs/sq.in. corresponding to 792 BHP. but at this load a slight smoke was visible in the exhaust. At the lower loads the exhaust was clear. The specific fuel consumption was 0.392 lb/BHP/hr. at nominal load at 1675 r.p.m.; the minimum fuel consumption was 0.366 lb/BHP/hr. at 1500 r.p.m. The fuel consumption | ||