Air Filter Selection:

An average foam filter will flow 4.38 cfm/sq-in.

A good paper filter will flow 4.95 cfm/sq-in.

An oiled cotton gauze (K&N) will flow 6.03 cfm/sq-in.

To get your required filtered surface area for a oiled cotton gauze filter:

A = filtering area (square inches)

A = ( CID * RPM ) / 20839

CID = cubic inch displacement

RPM = rev./min. at max power

Then using the following modifying factors if using an alternative filter media:

A * 1.3767 = required surface area for foam element

A * 1.2181 = required surface area for paper element

Horsepower and Torque:

HP = (TQ * RPM ) / 5252

TQ = ( HP * 5250 ) / RPM

Corrected BHP = BHP * (1 - ((elevation/1000) * .03))

Horsepower, ET, and Weight:

A quick calculation for horsepower based on your 1/4 mile trap speed:

HP = ( TS / 234 )^3 * weight

HP = Horsepower

HP = ( TS * 0.00426 )^3 * weight

TS = Trap Speed (MPH)

This horsepower output is the minimum required for the specified trap speed.

It assumes ideal track conditions, weather conditions, traction, and vehicle aerodynamics.

It will understate horsepower required at speeds exceeding 100 mph.

ET = 5.825 * ( weight / HP )^(1/3)

Weight = ( ET / 5.825 )^3 * HP

HP = weight / ( ET / 5.825 )^3

For a quick idea of ideal ET assuming good street rubber and decent traction....

ET = 1363 / MPH

Horsepower:

Calculation assuming sea level and known Volumetric Efficiency

AP = pressure in psi

CR = compression ratio

HP = ( AP * CR * VE * CID * RPM ) / 792001.6

VE = volumetric efficiency

CID = cubic inch displacement

RPM = revolutions per minute

To convert from Barometric pressure in inches of mercury to psi:

PressurePsi = (pressureHg * 3376.85 ) / 6894.757

Cubic Feet per Minute:

Theoretical Engine CFM = ( CID * RPM ) / 3464

Actual Engine CFM =  ( CID * RPM * VE ) / 3464

Carburator CFM = ( CID * RPM * VE ) / 2820

Volumetric Efficiency:

VE = ( Actual CFM * 1728 ) / ( CID * RPM )

VE = ( Actual CFM *100 ) / ( Theoretical CFM)