Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Compression Ratio

Required number input.

Specific Heat Ratio

Required number input.

Ideal air-standard Otto-cycle thermal efficiency 1−1/r^(γ−1) from compression ratio and constant heat-capacity ratio. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Efficiency Fraction

The resulting efficiency fraction returned as a number.

• Ideal Otto-cycle efficiency assumes constant specific heats, reversible adiabatic compression and expansion, and idealized heat addition. Real engines include combustion duration, heat loss, pumping, dissociation, friction, and variable properties.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Thermal Time Constant

  Lumped thermal first-order time constant from thermal resistance and heat capacity, τ=Rth Cth.

• Battery SOC Coulomb

  Ideal battery state of charge after a constant discharge current, using nominal amp-hour capacity; ignores coulombic losses and aging.

• Heat Energy Specific Heat

  Sensible heat required for a mass with constant specific heat capacity over the chosen temperature interval.