Power test means and method for internal combustion engines

Abstract

Means for and method of testing the power of an internal combustion engine. A tachometer means coupled to the engine generates one electrical pulse per engine cycle of the engine. While the engine is full-throttle accelerated, a computer means measures the time periods between successive pulses, each time period constituting the reciprocal of the average engine speed during the particular engine cycle. One-half of the time period corresponding with a low speed and one-half of the time period corresponding with a high speed are added to the intermediate time periods to determine an acceleration time period which is a measure of engine power. The acceleration rate is determined by subtracting the reciprocal of the time period corresponding with the low speed from the reciprocal of the time period corresponding with the high speed to determine the speed change, and dividing the speed change by the acceleration time period. Brake torque is determined by multiplying the acceleration rate by the known inertia of the engine. The engine is then shut off and the deceleration rate is determined and is multiplied by the known inertia of the engine to determine the friction torque of the engine. The brake torque is added to the friction torque to determine the indicated (total) torque of the engine.