The TooHighPsi Belt Length Calculator is a tool to provide an accurate estimate of a supercharger belt’s outer circumference on your Corvette or Camaro/CTS-V/CT5-V. This tool specifically applies to LT4 engines or vehicles using an LT4 drive. This is the same way we purchase belts for our own vehicles, optimized for a web browser. Before finding your outer circumference, please read through these considerations to find the right belt.

What is an “Outer Circumference”

Outer Circumference is a measurement of the total length around a V-belt’s outside surface and used by most belt manufacturers to describe length. This is not effective length which has variation from manufacturer to manufacturer.

How do I use “Outer Circumference” to pick the right belt?

The value you will receive from our calculator is a theoretical minimum length. As if the tensioner is pulled right to its limit and a routed belt can barely slip on.

We recommend purchasing a belt .5”-1.0” longer outer circumference than the calculated value. This first belt is an estimate and may not be an optimized fit. V-Belts often have a +/-0.5" tolerance from factory.

This is to ensure that the belt can fit as shelf life after manufacturing can cause belts to shrink.

Where do I go to find my belt?

Below are links to Gates belt catalogs

Gates Micro-V Belt Catalog

Gate Micro-V HD Belt Catalog (Fleetrunner)

Remember to filter the number of ribs you need and use outer circumference – not effective length.

How do I find my idler and supercharger pulley diameters?

Use the following table as a guideline for common idler and supercharger pulley sizes. For configurations not included on the table, use a caliper to measure your idlers outer diameter in millimeters. (1" = 25.4mm)