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2003-2004 Cobra Supercharger Belt Chart

Created by Jay Walling
Date Created: 3/28/2017
Last Updated: 12/12/2023

Have you just installed a new supercharger or idler pulley on your 03-04 Cobra and need a new belt? Check out our belt guide for the right info!

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2003-2004 Ford SVT Mustang Cobra Supercharger Belt Guide - 2003-2004 Ford SVT Mustang Cobra Supercharger Belt Guide

LMR has put together this guide to help you decide which belt you need for most of the popular combos using a stock Eaton blower and multiple pulley combinations. Here are the breakdowns below explaining most of the possible combinations for the 03-04 Ford Mustang Cobra.


While we have determined that these lengths are the most accurate lengths needed, these belt suggestions should be used as a guide. Each recommendation should be within 0.5" of less of the ideal length. With differences in tension strengths, manufacturers, and OEM tolerances, variances in length can differ.

2003-2004 Cobra Supercharger Belt Guide
Pulley Setup - With Factory Eaton Supercharger 3.65" Stock Upper Pulley 3.00" Upper Pulley 2.90" Upper Pulley 2.80" Upper Pulley 2.76" Upper Pulley 2.70" Upper Pulley
Stock Lower Pulley 7.375" 75.50" 74.50" 74" 73.50" 73.50" 73.50"
2 lb. 8.0" Lower Pulley 77" 76.50" 76" 75.50" 75.50" 75.50"
4 lb. 8.6" Lower Pulley 78" 77.50" 77" 76.50" 76.50" 76.50"
6 lb. 9.10" Lower Pulley 79" 78.50" 78" 77.50" 77.50" 77.50"
8 lb. 9.50" Lower Pulley 80" 79.50" 79" 78.50" 78.50" 78.50"
10 lb. 10.0" Lower Pulley 81.50" 81" 80" 79.50" 79.50" 78.50"
Stock w/ 4 Piece Idler Kit 77" 75.50" 75.50" 75.50" 75.1" "

For those who are running a larger alternator pulley, follow the guidelines outlined by Metco.

  • METCO Auxilary 90mm Snub Idler Idler - Add 1" and add 1.5" if the bracket is fitted with a 100mm idler pulley.
  • 3.00" Alternator Pulley - Add .5"
  • 3.20" Alternator Pulley - Add 1"
  • 3.50" Alternator Pulley - Add 1.5"
  • 3.70" Alternator Pulley - Add 2"
  • Add 0.5" to the calculated belt length any time a 100mm pulley is used in place of a 90mm pulley on the blower drive. If multiple pullies are changed to 100mm, then add these figures up accordingly.

Source: Alldata.com-Ford Motor Company

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About the Author

Jay has written content for Late Model Restoration for over 10 years, producing over 120 articles. Jay has an extensive 25-plus-year background in automotive and is a certified Ford Technician. Read more...