Turbo Sizing Calculator

Turbocharger selection from engine displacement and power target.

Engine displacement (ci)

Target HP

Boost pressure (PSI)

Peak RPM

Ambient temp (°F)

Compressor efficiency (%)

Tab to move between fields

Pressure ratio

1.95

Required airflow (CFM)

1,220.9

Engine demand (CFM)1,220.9

HP-based flow (CFM)52.6

Compressor outlet (°F)438

Temp rise (°F)363

Displacement (L)5.74

Suggested turbine A/R0.96

Turbo ClassVery large frame (GT42+ / T4-88+)

How to Use This Calculator

How the result changes with Boost pressure (PSI)

Engine displacement (ci): Engine displacement in cubic inches (e.g. 350 ci = 5.7L). Multiply liters × 61.02 to convert.
Target HP: Desired wheel horsepower at peak boost.
Boost pressure (PSI): Target boost pressure in PSI gauge (typical street: 8-15, race: 15-30+).
Peak RPM: Engine RPM at which peak boost and power occur.
Ambient temp (°F): Ambient air temperature in degrees Fahrenheit.
Compressor efficiency (%): Compressor adiabatic efficiency (typical peak: 70-78%).

Pressure ratio: Compressor pressure ratio = (boost + 14.7) / 14.7.
Required airflow (CFM): Recommended compressor map flow rate in cubic feet per minute.
Engine demand (CFM): Airflow the engine needs at given RPM and boost.
HP-based flow (CFM): Airflow needed purely based on target HP.
Compressor outlet (°F): Air temperature leaving the compressor before intercooler.
Temp rise (°F): Temperature increase across the compressor.
Displacement (L): Engine displacement converted to liters.
Suggested turbine A/R: Approximate turbine housing A/R ratio for your displacement.

Identify Input Parameters
4 parameters
Engine displacement (ci) = 350, Target HP = 500, Boost pressure (PSI) = 14, Peak RPM = 6500 = 6 input(s) provided
Calculate Pressure ratio
Pressure ratio = (boostPsi + 14.7) / 14.7
1.952 = 1.952
Calculate Required airflow
Required airflow = max(engineAirflowCfm, targetAirflowCfm)
1220.9 = 1220.9
Calculate Engine demand
Engine demand = (displacement / 2) * (peakRpm / 1728) * ve * pressureRatio
1220.9 = 1220.9
Calculate HP-based flow
HP-based flow = targetHp / 9.5
52.6 = 52.6