Cylinder Fill: the amount of air/fuel volume that is achieved in a certain area in a controlled amount of time, in this case the given amount of time is the time in which the camshaft is open (from .000" - .650") per valve per sequence.

Torque: the moment of a force; the measure of a force's tendency to produce torsion and rotation about an axis.

Horsepower: a unit of power in the U.S. Customary System, equal to 745.7 watts or 33,000 foot-pounds per minute.

Most cylinder heads today are ported to try and achieve large air flow numbers from .400" - .650" lift. But by having big air flow numbers at these lifts, air flow is sacrificed in the cam lift range of .100" - .400" and you must rev the engine at a much higher R.P.M. to keep it in the power curve.

Hot-Shot Motorworks has learned that the optimal port is to obtain the largest total accumulated amount of air flow through the port within the total lift of one valve sequence. How we obtain this number is to add all of the air flow numbers at each given lift of the camshaft from .100" - .600" lift, this is the amount of air/fuel mixture that is being passed through the port to fill the cylinder and combustion chamber. The higher the number, the more cylinder fill you have achieved and this is what creates torque.

Don't be mislead with large air flow numbers at maximum lift.