Boost pressure ratio calculator

How to use the calculator

1. Enter your boost pressure in PSI. This is the pressure in your intake manifold above atmospheric pressure.
2. Enter your atmospheric pressure in PSI. Standard sea-level atmospheric pressure is approximately 14.7 PSI.
3. Click the "Calculate" button to compute the boost pressure ratio.
4. Review the results and interpretation to understand your engine's boost characteristics.

Understanding Boost Pressure Ratio

The boost pressure ratio is calculated as:

Boost Pressure Ratio = Boost Pressure / Atmospheric Pressure

This ratio indicates how much pressure is being multiplied in your engine's intake system compared to outside air pressure.

Practical Applications

• Performance tuning: Helps determine if your engine is operating safely within boost limits
• Engine management: Assists in setting appropriate fuel pressure and ignition timing
• Component selection: Guides turbocharger and intercooler sizing for desired performance

Example Scenarios

A boost pressure of 13.5 PSI with standard atmospheric pressure (14.7 PSI) produces a pressure ratio of 0.92, indicating a slight vacuum condition. This might occur in certain engine designs or at high altitudes.

A boost pressure of 23 PSI with standard atmospheric pressure produces a pressure ratio of 1.57, indicating significant boost multiplication that requires proper engine management.