Instrument for measuring engine clearance volumes S. W. Sparrow naca-tn-27 Dec 1920 With the advent of the V type engine, a new method to measure the clearance volume in cylinders was needed. It was suggested that this measurement could be made by a process which consisted essentially of simultaneously changing both a known and unknown volume of gas by a known amount and then calculating the magnitude of the unknown from the resulting difference in pressure between the two. An instrument based on this design is described. An Adobe Acrobat (PDF) file of the entire report: http://naca.central.cranfield.ac.uk/reports/1920/naca-tn-27.pdf S. W. Sparrow; Instrument for measuring engine clearance volumes; naca-tn-27; Dec 1920