Engine Air Fuel Ratio (\(A/F\)):

\[ A/F = \frac{137.3 \left( x + \frac{y}{4} - \frac{z}{2} \right)}{\phi \left( 12x + y + 16z \right)} \]

Where:

• \(A/F\) is the mass of air required per unit mass of fuel.
• \(x, y, z\) are the number of carbon, hydrogen, and oxygen atoms in the fuel molecule.
• \(\phi\) is the equivalence ratio.