KJ Jones Senior Technical Editor
June 1, 2008
Photos By: KJ Jones
PA Performance's 130-amp 3G high-output alternator (PN 1619; $199) gleams like a diamond in the engine compartment of Victor Alvarez's '93 GT. Swapping a 5.0's stock alternator with this unit is a highly recommended upgrade, especially if your 'Stang is or will be loaded with 12-volt-powered accessories.

Horse Sense: Before new alternators are released for sale, manufacturers evaluate their products using an industry-standard test sequence that covers a variety of outputs: maximum power, regulator set points, and amperage. Testing your 'Stang's alternator is a quick and easy procedure that requires only a voltmeter and a few minutes of your time. By giving your Pony's electrical system some attention from time to time, you might save yourself the headache of being inconveniently stranded on the side of the road without power.

Imagine this scenario: You're enjoying a nighttime cruise in your Fox Mustang and all seems right with the world. But a few moments after you pull up to a traffic signal and take in the signature burble of a healthy 5.0 at idle, you notice the 'Stang's dash illumination has dimmed a bit, and the beam of light coming from the headlamps is abnormally subdued as well.

Your logical, knee-jerk assessment of the problem is that the battery is either dead or dying, so you go to the local auto parts store and purchase a new 12-volt cell for your Pony. The natural assumption after replacing the battery is that everything is good; but two days later, the lights are dimming once again. What's the problem?

Consider this. When it comes to keeping a Pony powered up, the alternator- not the battery-is the real star player on a Mustang's electrical team. An alternator basically takes energy from an engine's crankshaft (transmitted through a serpentine belt) and converts it to the electrical energy (measured in amps) that a car's 12-volt battery depends on for maintaining its charge.

Before disconnecting the negative battery cable, we checked out the voltage and amperage coming from the stock electrical works in Vic's Mustang. With the engine running at idle, the voltmeter showed 14.39 volts coming from the battery. Victor's 'Stang had been sitting for a long time, so we had to jump the battery and therefore got a higher-than-normal reading. Normal voltage for a fresh battery is approximately 13.5 volts.

A 5.0 Fox's stock electrical system is anchored by a 2G (2nd Generation) 75-amp alternator, which performs admirably on 'Stangs that are still in mostly original trim or accessorized with only a few 12-volt (activated), low-amp-draw aftermarket components. Problems tend to arise when mods become more aggressive. The amperage draw of electric fans and water pumps, high-volume electric fuel pumps, nitrous solenoids, high-output ignition systems and engine-management systems, and even high-output stereos can put a serious beating on an OEM alternator. The excessive load eventually leads to alternator failure, usually without any warning. Some of you may have experienced what we think is the worst possible failure: fire.

Because of their three-prong spadeconnector design, in which current from the alternator is actually shared by two of the spades, 2Gs are prone to experiencing excessive resistance in the electrical path because of the overload. That creates big-time heat and can cause the factory wire harness to melt or catch fire. Ford Motor Company acknowledged this problem in 1996 and issued Technical Service Bulletin No. 96214, which instructed dealership technicians and do-it-yourselfers to install an upgraded wiring-connector kit (PN E5AZ-14305-AA) to eliminate the possibility of an electrical burndown.

With the battery connected, amperage checked in at 350 amps on Extreme's Auto Meter battery tester. PA recommends using the large OEM pulley on its 3G alternator, so Saul swapped the two prior to final installation. A smaller underdrive pulley, which reduces the speed that the 3G spins and improves the unit's output at idle, is included with the kit.

In our opinion, a better remedy for this problem is a high-output version of the 130-amp 3G (3rd Generation) alternator that Ford made standard on Mustangs in1995. PA Performance's version of the 3G is built with new internal components and has tolerances that exceed Ford's specs. The alternator's charging capacity is roughly three times greater than that of a stock version, which enables it to produce full output at lower rpm (up to 150 amps at 3,000). A stock version needs 4,000 rpm or better to reach its peak output, which is usually only 80 amps at best.

Victor Alvarez owns the stonestock '93 Mustang GT we're using for this project. Extreme Automotive's Saul "The Surgeon" Gutierrez is installing PA's 3G (PN 1619; $199) and heavy-duty Alternator Power Wire Kit (PN 9902-A; $59) on Vic's Pony so we can see firsthand the amount of improvement (amperage output) the bigger alternator makes. The swap will also protect the 'Stang's electrical system against the damage that can result from the potential heat problems explained earlier.

We realize the 3G alternator upgrade isn't new, and many Fox owners with heavily modified Mustangs have already performed the conversion. But similar to most stock '93-or-older Foxes still on the road, Victor's ride is long on miles, and its charging system has never been inspected or upgraded beyond replacing the battery.

Read on to see how simple it is to install a 3G alternator system. The job can be accomplished in less than two hours with basic handtools, as well as a grinding tool for modifying the factory alternator bracket.

Photo Gallery

View Photo Gallery

Photo Gallery

View Photo Gallery