Army Testing 800 b.h.p.
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Petrol-injection Engine
A'present on trial by the Army is an -800 b.h.p. petrol-injection engine designed for vehicle • use. Maj.-Gen. C. Bullard gave this news in a paper read to the Diesel Users' Association, in London, yesterday. He was not able to supply details, but he said that elaborate control of the fuel pump was necessary and that lubrication presented complications. Nevertheless some success had been achieved.
On the main subject of his paper— the use of oil engines in the Army— he said that the question of fuel was dominant and made the oil engine appear in a less favourable light than it would if allowed to be developed and employed on its merits.
The volumetric fuel consumption of the oil engine was approximately only two-thirds that of a spark-ignition engine of equivalent power, and for the Army this was one of its most attractive advantages. A vehicle could either be given a greater range with a fuel tank of equivalent capacity, or could retain the same range and allow more room for the crew or the housing of additional ammunition. 11 was also important in administration.
Detergent lubricating oils, he said, had been entirely satifactory and no record existed of any undue wear which might have occurred in engines being attributable to their use., It had been found that when petrol was burned in a compression-ignition engine, combustion knock was excessive, fuel consumption was high, the exhaust system ran red-hot, and fuelvapour locking was encountered. Nevertheless, said Maj.-Gen, Bullard, one might well ask whether it was, in fact, beyond the bounds of scientific possibility to devise a means for altering the characteristic of the higher distillates so that they could be used for compression-ignition engines.
Oil-bath air cleaners were more or less standard equipment in the Army, but the proportionately large air cleaner which was required for an oil engine was a disadvantage.
It was the Army's general idea that the bulk of its equipment should be able to operate without major mod tiications down to a temperature of about –20°F. As an aid to starting under extreme conditions of cold, oil dilution had been employed successfully, without engine warming, in temperatures as low as –40°F.
Down to –20°F., oil fuel could be diluted by 15 per cent. and below –20°F. down to –40°F. 25 per cent. was required. Some operators were said to have drained engine oil into the snow at the end of the day's :tin and the next morning to have picked up the frozen slab and melted it in a pan, with satisfactory results. With constant running at correct engine temperature, the oil fuel used for diluting the lubricating oil was driven off in two to four hours.