How to Use This Calculator
- Enter the engine's compression ratio (typically found in the owner's manual or specifications). This is the ratio of the volume in the cylinder at bottom dead center to the volume at top dead center.
- Input the engine's cubic inch displacement (CID), which can be calculated from bore × stroke × number of cylinders × 0.7854.
- Set the ambient barometric pressure. The default is 14.7 PSI (standard sea level), but you can adjust this for different altitudes.
- Click the "Calculate" button to compute the results.
Understanding the Results
The calculator provides three key outputs:
- The approximate maximum pressure in the combustion chamber during the compression stroke, based on the ideal gas law and adiabatic compression assumptions.
- Absolute Combustion Chamber Volume: The volume of the combustion chamber at top dead center.
- Volumetric Efficiency Estimate: A rough calculation of how efficiently the engine draws in air/fuel mixture during the intake stroke, based on the compression ratio.
Important Notes
This calculator provides a simplified estimation of peak cylinder pressure. Actual peak pressures can vary based on:
- Real-world combustion efficiency
- Engine tuning parameters
- Altitude and atmospheric conditions
- Specific engine design factors
For precise engine analysis, consult professional engine tuning resources and measurement equipment.