Second Strike Air Cleaner Calculator


  for documentation (requires Adobe reader)

Specify Engine

  Peak Horsepower

  at rpm

  Cubic Inch Displacement

  Engine Type

Specify Air Cleaner

  Air Cleaner Shape

  Air Filter Type

Diameter (outside diameter in inches)

Length (for oval shape, outside length in inches)

Height (overall height included molded surfaces in inches)

Number of Air Cleaners

Pressure and Power Loss at RPM

Filter flow Area (in square inches)

Filter discharge coefficient

RPM Pressure Loss (percent) Horsepower Loss
The model is designed primarily to let you know if an air filter works for your engine or not. For performance applications, you should shoot for a pressure loss in the 0.5% to 1.0% range at the peak power rpm. Less is better.

It is not intended to yield precise three digit answers because a precise model would require more input (such as the number and depth of the pleats, flow bench airflow numbers for the material, volumetric efficiency curves and horsepower curves for the engine) than the average owner knows or would be willing to find out. And it really isn't necessary. When picking an air cleaner, it isn't important to know if the loss is 2 horsepower or 2.1. You really want to know if it is 2 (OK) or 10 (maybe) or 20 (not OK). The input has been simplified as much as possible to make the model usable by making a number of simplifying assumptions. The mathematical basis for the calculation is contained in the Technical section of the documentation (see Help) for those who are interested.

The model is for normally aspirated engines. It is not designed for blowers, turbos or nitrous. This model is for round and oval air cleaners with perimeter filter elements. It is not designed for filter elements in the lid.