Abstract: A measuring and processing electronic circuit for measuring and visually displaying digitally the horsepower per cylinder selected for a reciprocating engine. Proximity sensors relate the rotation of cylinder by way of the fly-wheel and the crank shaft, to r.p.m. of the engine, and instantaneous position of the cylinder in the stroke. There is also provided a representative pulse for each degree through 360.degree. of the revolution of the flywheel. A pressure transducer is mechanically linked to each cylinder in the engine. A selector switch selects which cylinder's horsepower is to be measured. In arriving at horsepower per cylinder the pressure measurement is multiplied against a volume signal for each degree through the revolution. The resultants for each degree are summed and multiplied against r.p.m. measurement for horsepower per cylinder.