What Size Pulley Can I Run
If you have you have a supercharged W Body you've almost certainly been tempted to swap your stock pulley for a smaller unit. After all, this is the easiest way to make power on the supercharged cars. Unfortunately it's also the easiest way to blow your engine if proper pre-cautions are not taken.
This brief article will discuss what it takes to run each specific pulley. This article should be used as a reference only. You should always scan for knock after switching to a smaller supercharger pulley. Click here for more information on knock.
Your vehicle is equipped with a 3.8" supercharger pulley stock. The one exception to this rule is a limited amount of SLP branded Grand Prix GTXs and Regal GSXs which were equipped with a 3.5" pulley as an option. Your vehicle will make about 6lbs of boost with the stock pulley depending on weather conditions.
This guide makes the following assumptions:
- You're driving a 1997 - 2007 Vehicle with the Series II/ III Supercharged Engine
- You're not running a converted L36/Topswap
- You're running a Gen III Eaton M90 Blower (add .10") to each listed size if you're running a 2004+ Grand Prix
For each .10" in pulley size you go down you will generally pick up 1lb of boost.
Core Modifications (3.5" - 3.4") - The following modifications should be present when any pulley smaller than stock is being used. They will also allow most vehicles to run a 3.5 - 3.4" pulley with no knock:
- Performance PCM (Or Tuner)
- Downpipe (or headers)
- Colder Thermostat (180 degrees)
- 2 heat range colder plugs (Autolite 104s)
3.3" - 3.2" - In addition to the modifications above:
- Ported Manifolds
- Headers (Instead of a downpipe & ported manifolds)
- Rockers (1.9 ratio)
- Mild Cam (Instead of rockers)
- Intercooler (Instead or in addition to rockers/ cam)
3.1" - 3.0" - In addition to the Core Modifications:
- Intercooler (Instead of in addition to rockers/ cam)
- Headers (Not absolutely Necessary but strongly recommended)
- Injectors (42.5lbs/ May not be necessary; depends on scanning)
2.9" - 2.6" - In addition to the Core Modifications:
- More aggressive cam or mild cam & mild rockers
We take no responsibility for any engine failures as a result of advice garnered through this article. A responsible owner will always scan for knock after changing their supercharger pulley.