Fuel-Air Mixture Heating Value Calculator

Why cylinder volume cares about mixture energy, not just fuel energy

Fuel heating value describes energy per kilogram of pure fuel, but a combustion chamber is filled mostly with air, not fuel - spreading that same fuel energy across the total mixture mass gives the figure that actually matters for engine performance tied to a fixed cylinder volume.

Worked example

For a fuel with 44,000 kJ/kg heating value at a 14.7 air-fuel ratio:

Mixture Heating Value = 44000 / (1 + 14.7) = 2,802.55 kJ/kg of mixture

This dramatic drop from 44,000 kJ/kg (pure fuel) to about 2,800 kJ/kg (full mixture) illustrates why cylinder-filling efficiency (volumetric efficiency) matters so much for engine power output - most of what fills a cylinder is air, not the energy-dense fuel itself.