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2003-2004 Cobra Supercharger Belt Chart

Created by Jay Walling
Date Created: 3/28/2017
Last Updated: 7/24/2026

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!

Viewing this install and using the information shared is subject to the terms set forth here - View the LMR Install Instructions Disclaimer.
2003-2004-ford-svt-mustang-cobra-supercharger-belt-guide_c8e3ab45.jpg (634×950)

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.

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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 Supercharger3.65" Stock Upper Pulley3.00" Upper Pulley2.90" Upper Pulley2.80" Upper Pulley2.76" Upper Pulley2.70" Upper Pulley
Stock 7.375" Lower Pulley75.50"74.50"74"73.50"73.50"73.50"
2 lb. 8.0" Lower Pulley77"76.50"76"75.50"75.50"75.50"
4 lb. 8.6" Lower Pulley78"77.50"77"76.50"76.50"76.50"
6 lb. 9.10" Lower Pulley79"78.50"78"77.50"77.50"77.50"
8 lb. 9.50" Lower Pulley80"79.50"79"78.50"78.50"78.50"
10 lb. 10.0" Lower Pulley81.50"81"80"79.50"79.50"78.50"
Stock w/ 4 Piece Idler Kit77"75.50"75.50"75.50"75.1"78.50"
 

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

  • METCO Auxiliary 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...