TECHNICAL DISCUSSION: AIRFLOW DYNAMICS

The total air flow through a gasoline engine determines its maximum horsepower. At peak power, a racing engine will use 1.67 cubic feet of air (CFM). To increase power output, either the air flow capacity must be increased or the air/fuel mixture charge must be burned more efficiently.

The flow bench is a measuring device designed to measure the air flow capacity of various engine components. Air is blown or sucked through the engine at standard air pressure and the air flow capacity is measured. In this manner, different parts can be compared and the effect of changes can be evaluated. The flow tests are conducted at constant peak air velocity, usually between 100 and 400 feet per second.

Additionally, an engine's efficiency and power can be increased considerably by taking advantage of natural dynamic effects which occur during the intake cycle. Both kinetic energy and resonant pulses can be harnessed to fill the cylinder with mixture. When the inlet closes, a pressure pulse bounces back out the intake track. By making intake track the proper length, the returning pulse can be timed to arrive at top dead center of the next cycle, pushing extra air in and keeping exhaust gas out.