OEM flywheels are designed to be a direct replacement for the stock flywheels of specific car/engine applications, retaining the same diameter (ring gear size) as originally equipped with the car.
In basic configuration provides 250 CFM free air flow or 220 CFM air flow installed in 3ft. total of flexible duct before and / or after the unit 6.5 in.H2O suction and 4.5 in.H2O pressure capabilities allow it to easily overcome flow restrictions that cause other blowers to lose as much as one third of their free flow capacity.