The object of this investigation is to make a study of the effect, on the economy and torque of a gasoline motor, of heating the air going to the carburetor. The knowledge gained from such an investigation is of considerable importance and might be used in determining the temperature at which to supply air to the carburetor of a motor in order to get the best results under its working conditions. General practice indicates that a motor will run more smoothly and first regularly when the temperature of the intake air is 150 degrees or more. The theory is that up to a certain point, the economy becomes better with increasing air temperatures. The brake horsepower, however, falls off as the temperature is raised. Assuming then that we have an unlimited heating source, it is our purpose to find the best temperature to use in order to obtain the highest economy without seriously reducing the torque. Also the effects at various loads and speeds will be considered. With the poor grade of gasoline now being supplied, this investigation should be of the utmost value.