Air-Fuel Ratio Calculator

About the Air-Fuel Ratio Calculator

The Air-Fuel Ratio (AFR) Calculator determines the ratio of air to fuel for combustion engines, aiding in optimizing engine performance and efficiency.

Calculation Method: Computes AFR by dividing air quantity by fuel quantity, supporting both mass (kg or lb) and volume (L or gal) inputs with appropriate density conversions.

Use this tool for tuning automotive engines, analyzing combustion efficiency, or educational purposes in mechanical engineering.

• Features:
  • Inputs: Air quantity, fuel quantity, input type (mass or volume), unit (metric or imperial), and fuel type (gasoline, diesel, ethanol, methanol).
  • Keypad includes digits (0–9) and decimal point (.) for numerical input.
  • Displays AFR and mixture type (rich, stoichiometric, lean) with calculation steps in LaTeX format using MathJax.
  • Clear, backspace, and copy functionality for results.
  • Share or embed the calculator.
• Practical Applications: Useful for automotive engineers, mechanics, tuners, or enthusiasts optimizing engine performance.
• How to Use:
  • Select input type (mass or volume).
  • Choose unit (metric or imperial).
  • Select fuel type.
  • Enter air and fuel quantities.
  • Use the keypad to input digits or decimal points.
  • Click "Calculate" to view AFR and mixture type.
  • Use "Clear" to reset or "⌫" to delete the last character.
  • Copy results or share/embed the calculator.
• Helpful Tips:
  • All inputs must be positive numbers.
  • Stoichiometric AFR varies by fuel: Gasoline ≈ 14.7:1, Diesel ≈ 14.5:1, Ethanol ≈ 9:1, Methanol ≈ 6.4:1 (by mass).
  • Rich mixtures (AFR < stoichiometric) provide more power but lower efficiency.
  • Lean mixtures (AFR > stoichiometric) improve fuel economy but may increase engine temperature.
  • Verify results with engine specifications or oxygen sensor data.
• Calculation Details:
  • Mass-Based AFR: \(\text{AFR} = \text{Air Mass} \div \text{Fuel Mass}\).
  • Volume-Based AFR: Convert volumes to masses using densities (\(\rho\)): \(\text{Air Mass} = \text{Air Volume} \times \rho_{\text{air}}\), \(\text{Fuel Mass} = \text{Fuel Volume} \times \rho_{\text{fuel}}\), then \(\text{AFR} = \text{Air Mass} \div \text{Fuel Mass}\).
  • Densities (metric): Air ≈ 1.225 kg/m³, Gasoline ≈ 0.74 kg/L, Diesel ≈ 0.85 kg/L, Ethanol ≈ 0.789 kg/L, Methanol ≈ 0.792 kg/L.
  • Densities (imperial): Air ≈ 0.0765 lb/ft³, Gasoline ≈ 6.17 lb/gal, Diesel ≈ 7.09 lb/gal, Ethanol ≈ 6.58 lb/gal, Methanol ≈ 6.61 lb/gal.
  • Mixture type: Compared against stoichiometric AFR for the selected fuel.
• Examples:
  • Example 1:
    • Inputs: Input Type = Mass, Unit = Metric, Fuel Type = Gasoline, Air Quantity = 14.7 kg, Fuel Quantity = 1 kg
    • Calculation:
      • AFR: \(\text{AFR} = 14.7 \div 1 = 14.7\)
      • Compare with stoichiometric AFR for gasoline (14.7): Stoichiometric mixture
    • Result: AFR = 14.7:1, Mixture = Stoichiometric
  • Example 2:
    • Inputs: Input Type = Volume, Unit = Imperial, Fuel Type = Ethanol, Air Quantity = 1000 gal, Fuel Quantity = 10 gal
    • Calculation:
      • Convert air volume to mass: \(1000 \times (0.0765 \times 7.4805) = 572.6 \, \text{lb}\)
      • Convert fuel volume to mass: \(10 \times 6.58 = 65.8 \, \text{lb}\)
      • AFR: \(572.6 \div 65.8 = 8.7\)
      • Compare with stoichiometric AFR for ethanol (9.0): Rich mixture
    • Result: AFR = 8.7:1, Mixture = Rich

Optimize engine performance with this interactive Air-Fuel Ratio Calculator. Share or embed it on your site!