Name: High Output Alternator [250a &amp; 320a]
SKU: 130902
Availability: InStock

Whether you’re powering dual fuel pumps, electric cooling fans, high-powered audio equipment, aftermarket lighting, or simply looking for a more reliable charging system, the JS Alternators High-Output Alternator is designed to deliver the amperage your Pontiac G8 demands.

Built as a true direct replacement for the 2008-2009 Pontiac G8 GT (6.0L) and GXP (6.2L), these alternators install in the factory location and utilize the original-style electrical connector for simple plug-and-play installation. The OEM-style regulator maintains factory voltage control, allowing the alternator to integrate seamlessly with your vehicle’s electrical system.

Choose between a 250-amp or 320-amp model depending on your vehicle’s electrical demands. Whether you’re building a street car with upgraded accessories or a serious performance vehicle running multiple fuel pumps, amplifiers, and auxiliary electronics, these high-output alternators provide the charging capacity needed to keep voltage stable under load.

To maximize charging performance, every JS Alternator includes a smaller diameter pulley, allowing the alternator to spin faster at engine speed and produce greater output throughout the RPM range. Because of the smaller pulley, installation requires a serpentine belt approximately ½” to 1″ shorter than stock.

For vehicles equipped with a high-output alternator, upgrading the charging system wiring is essential. JS Alternators requires a properly installed Big 3 Wiring Upgrade using 1/0 AWG 100% copper cable to safely handle the increased current output. Failure to perform this upgrade can lead to charging issues and will void the manufacturer’s warranty.

Looking to personalize your engine bay? Every JS Alternator is available with a wide selection of custom powder-coated finishes for an additional charge, giving you the opportunity to match your alternator to the rest of your build. Since each alternator is individually built and powder coated to order, custom finishes are non-refundable.

If your Pontiac G8 has outgrown the capabilities of the factory charging system, the JS Alternators 250A and 320A High-Output Alternators provide the power, reliability, and quality needed to support today’s demanding electrical upgrades.

Fits 2008-2009 Pontiac G8 GT (6.0L) and GXP (6.2L).
Available in 250-amp and 320-amp output ratings.
Requires a serpentine belt approximately ½” to 1″ shorter than stock due to the smaller alternator pulley.
A Big 3 Wiring Upgrade using 1/0 AWG 100% copper cable is required and is necessary to maintain warranty coverage.
Custom powder-coated finishes are available for an additional charge.
Each alternator is built to order and backed by a 1-year manufacturer’s warranty, with optional extended warranty coverage available through JS Alternators.

REQUIRED Installation Steps:

(Wear eye protection, remove jewelry/loose items, and allow car to fully cool before starting installation)

Batteries must be fully charged before installation.
Make sure vehicle is off and engine is cool.
Disconnect the negative cable from the battery/batteries.
Disconnect all other wiring from the alternator.
Remove the belt (note the belt routing before removing).
Remove the bracket bolts and original alternator.
Mount the new alternator. Typically the original bolts will be used.
The belt must be replaced with a .5 to 1-inch shorter belt when installing a high output alternator, unless otherwise specified.
Install the new belt. Make sure the routing is correct and the belt is aligned with all pulley grooves.

Connections Of Frame/Body: Clean all metal surface of any paint or rust with a wire brush or die grinder. Use a conductive corrosion inhibitor available at any electrical parts supply store.

Grounding (Uni-body frame warning): Many newer vehicles have “uni-body” or sheet metal frame structures with no traditional “full frame”. Because of seams and adhesive attached body components, additional steps may be required for proper chassis grounding. Choose the location on the sub-frame with the thickest metal possible. If there is lower than spec charging voltage at the battery, move ground connections or add additional ground cables to different frame components.

*** WARNING *** Keep all electrical wiring at least 12” away from heat sources to avoid fire of the cable jacket!