This paper discusses an inexpensive, non-contacting sensor for the measurement of the quasi-average torque of an internal combustion engine. The quantity which is actually measured by this sensor is a low-pass filter transformation of instantaneous developed torque having a bandwidth of about 9Hz. This method of torque measurement uses an inexpensive sensor which directly measures instantaneous crankshaft angular velocity. Electronic signal processing generates a signal which is proportional to instantaneous crankshaft angular acceleration.The relationship between engine developed torque and various transformations of this acceleration have been experimentally studied. This paper shows that certain of these transformations are highly correlated with the desired torque signal under transient as well as steady state operation. Transient operations which have been studied include changes in throttle position.The paper explains the sensor concept in terms of specific mathematical models for the torque and engine dynamics.