Calculate Jet Size Changes for Different Conditions


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These equations are for recreation only.

This Jet Size Calculator will give you the size of the jet you need for a different weather condition.
You will have to know what the air density is for your current jetting that is correct for your tune.
You will also need to know the diameter of the hole of your jet.
This is usually the jet size in inches.
75 Holley jet is around .075" diameter
120 pill size is usually about .120" diameter
It's up to you to know the correct diameter, though.
Here is a link to an Air Density Calculator

For sea level: Normal Tempature Pressure at 20°C (68° F) and 1 atm (101.325 kN/m2, 101.325 kPa) of pressure:
use 1.204 kg/m3 ( as for original air density in calculator)

Jet Size Calculator

Original Jet Diameter inches
Air Density at Original Jet Size kg/m3
Air Density Now kg/m3

Input DATA Please
Old Jet Size inches
Old Density kg/m3
New Jet Size inches
New Density kg/m3