Abstract
In a previous paper the author showed that in the case of a particular high-speed compression-ignition engine the weight of air received varied directly with the absolute pressure and the three-fourths power of the absolute temperature of the air at the engine intake. Information obtained later from a number of engines of differing size and design showed that the three-fourths power held good in every case. From this it is concluded that the three-fourths power has general application to the high-speed compression-ignition engine.
On application of this factor to the supercharged engine it has been found to hold good here also. In this case, however, it is necessary to take into account the additional weight of air received by reason of the pressure in the clearance volume being raised to that at the engine intake. A factor for taking this into account is given for a range of compression ratios and intake conditions together with a method for calculating the air consumption under any given set of intake conditions.
In the case of a supercharged engine provided with a wide valve overlap the quantity of air which passes directly to the exhaust during the overlap period may be determined by calculating the quantity of air that will be retained within the cylinder for the prevailing conditions and subtracting this from the measured air consumption.
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