Second Strike Carburetor Calculator

Updated 9/5/2011 See last page of help for details


   for documentation. Requires Adobe Reader. (Second Strike V8 N1)

Specify Engine

  Peak Horsepower

  at rpm

  Cubic Inch Displacement

   Engine Type (scroll down for description)

Specify Carburetor

  CFM Rating of Carburetor

  Carburetor type: 4 = 4-barrel, 2 = 2-barrel

  Number of Carburetors (1 to 6)


Estimated Airflow at Peak Horsepower

CFM - Recommended carburetor size

Maximum rpm

Maximum rpm used in analysis

 Minimum rpm

  Minimum rpm for full throttle for specified CFM Rating

for 4-barrel with mechanical secondaries (double pumper).

Pressure and Power Loss at RPM for Specified Engine Type

RPM Airflow
Efficiency VE
Pressure Loss (percent) Horsepower Loss

For Comparison, Estimated Airflow at Peak Horsepower for Each Engine Type

  CFM  for Street

  CFM for High Performance Street

  CFM for High Performance Street/Track

  CFM for Race

  CFM for Ram Tuned Race

The Second Strike Carburetor Calculator and the accompanying Help document are designed to assist the car and engine builder/modifier looking for balanced performance a car that is both enjoyable to drive on the street and competitive on the track.


It is recommended that you read the Help documentation, particularly sections Input and Results, before using the Carburetor Calculator.


Engine Type

Street: Stock street engines.

High Performance Street: Modified engine suitable for street driving. Upgraded heads, header, cam, intake, and carburetor. For 1970s vintage performance parts.

High Performance Street/Track: Modified engine suitable for street and track driving. Upgraded heads, header, cam, intake, and carburetor. For modern performance parts.

Race: Modified engine not suitable for street driving.

Ram Tuned Race: Modified engine with intake and exhaust runner lengths ram tuned for peak power rpm.


The Carburetor Calculator allows you to evaluate different sized carburetors and will tell you how well each performs on your engine by calculating the pressure drop and horsepower loss over a range of engine speeds. You can then determine if this is the right size for your engine.


The calculations are based on equations and data supplied by Holley. Simplifying assumptions have been made to reduce the amount of input and make the calculator easy to use. The mathematical basis for the calculations is contained in the Technical section of the Help documentation for those who are interested.


The Calculator is designed for normally aspirated engines with one or more carburetors drawing through a common plenum, or fuel injection with a single common throttle body. It is not designed for blowers, turbos, or nitrous or for individual runner systems such as Weber carburetors or multi-stack fuel injection.