Otto Cycle Pressure Calculator

Pressure in the cylinder at the beginning of the compression stroke (P₁):

Pressure in the cylinder after the compression stroke (P₂):

Pressure in the cylinder at the beginning of the expansion stroke stroke (P₃):

Pressure in the cylinder after the expansion stroke (P₄):

Temperature at the beginning of the compression stroke (T₁) :

Temperature after the compression stroke (T₂) :

Temperature at the beginning of the expansion stroke (T₃) :

Temperature after the expansion stroke (T₄) :

How This Is Calculated

During compression (process 1-2): $$ P_2 = P_1 \cdot \left(\frac{T_2}{T_1}\right) $$ During expansion (process 3-4): $$ P_4 = P_3 \cdot \left(\frac{T_4}{T_3}\right) $$
where:

P₁ = Pressure in the cylinder at the beginning of the compression stroke (Pa)

P₂ = Pressure in the cylinder after the compression stroke (Pa)

P₃ = Pressure in the cylinder at the beginning of the expansion stroke stroke (Pa)

P₄ = Pressure in the cylinder after the expansion stroke (Pa)

T₁ = Temperature at the beginning of the compression (K)

T₂ = Temperature after the compression stroke (K)

T₃ = Temperature at the beginning of the expansion stroke (K)

T₄ = Temperature after the expansion stroke (K)

Assumptions

The working fluid behaves as an ideal gas.
Specific heats remain constant.
Compression and expansion processes are adiabatic.
There is perfect mixing of the air and fuel.

Related Calculators

Otto Cycle Compression Ratio

Otto Cycle Efficiency

Otto Cycle Heat Added (Combustion Process)

Otto Cycle Heat Rejected (Exhaust Process)

Otto Cycle Temperature