Combustion Chamber Pressure Calculator

Combustion Chamber Pressure Calculator: Constant-Volume Pressure Rise

In a fixed-volume combustion chamber, such as during the power stroke of a piston engine before the exhaust valve opens, both the number of gas moles and the temperature change dramatically as fuel burns, driving a large pressure rise. This calculator applies the ideal gas law to estimate that change.

The Formula

P2 = P1 × (n2/n1) × (T2/T1)

Worked Example

A chamber starts at 101.325 kPa with 1 mol of gas at 298 K, and after combustion has 1.05 mol at 2,200 K.

P2 = 101.325 × (1.05/1) × (2200/298) = 785.4 kPa

How to Use This Calculator

1. Enter the initial pressure, moles of gas, and temperature.
2. Enter the final moles of gas and temperature after combustion.
3. Click Calculate to get the resulting pressure.

Related Calculations

Use with the Mean Effective Pressure Calculator for engine cylinder pressure analysis.