Converting your old alternator to a modern one-wire system may not sound exciting on the surface. However, installing this Powermaster unit is one of those special mods that checks all the boxes. First off, a modern, one-wire alternator provides a lot more functionality and capability to our 1965 Mustang’s electrical system. Moreover, the installation is dead simple and easy and we are introducing some more reliability into the car while cleaning up the wiring in the engine bay.
Powermaster’s Street alternator (PN 8-57141) for this application features a black power-coated finish and delivers a peak output of 150 amps.
The world is a vastly different and much more complicated place than when this classic Mustang first rolled off the assembly line in the mid ’60s. Back then, the most complex electronic device was its AM radio and single speaker in the dash, which seems downright archaic when compared to the dozens of highly sophisticated computers and precision systems found in modern Mustangs. Each one is more power-hungry than the last. The original charging system only had to power the ignition, lights, blower motor, gauges, and the aforementioned radio with its single speaker. That’s it.
You can see how the one-wire design of the Powermaster alternator (right) cleans up the wiring versus the factory unit (left). The process of installing Powermaster’s Street Alternator couldn’t be any simpler. First, remove the battery. Next, unplug the harness from the alternator and the voltage regulator. Then, you can remove the alternator’s 9/16 bolt from the bottom, and remove the belt followed by the 5/8 bolt from the top and the alternator will be free to come out.
The continuous goal with this car is and will always be to keep driving it, so we are always on the lookout for mods that will improve its drivability and performance. Last year, we installed Holley’s Sniper 2 fuel injection system which did a ton to improve the everyday driveability and performance of the car. However, its new ECU, electric fuel pump, modern ignition components, and electronic fuel injection put a serious strain on the car’s electrical system. Combined with the electric cooling fan and more modern stereo already installed, the OE Motorcraft alternator struggled to keep up with voltage, sometimes falling to 11.8 volts at idle with everything humming away. I desperately needed a better solution and fast!
Powermaster’s Street Alternator provided the perfect solution to my classic Mustang’s power and electricity demands. Powermaster’s one-wire alternator system puts out 100 amps at idle and up to 150 amps at the top end of the rev range. If we compare that to the OE motorcraft alternator, which puts out anywhere between 30-40 amps at idle, it nearly triples the output.
Removing the factory external voltage regulator cleans up the engine compartment, but because we bypassed the old unit, the charging light does come on the dash, which requires a better solution than removing the bulb.
You can think of our amp output as the “capacity” of the electrical system. Simply adding the amp draw from our various components and systems delivers a pretty reasonable conclusion on our power needs from our alternator. In fact, Powermaster’s website has an excellent worksheet to help you figure this out and guide you to the right size alternator. The Street Alternator, with its 100/150-amp output, should provide plenty of juice to keep our systems and accessories happy.
The existing wiring coming off the alternator was pretty hacked, which required creating a new connection. Powermaster offers its Alternator Wire kits (PN 1-585-130) to upgrade your connection. Lastly, it’s a good idea to add a large fuse between the alternator and the battery for some extra safety, and it’s something we plan on doing sooner rather than later.
So, what is a one-wire alternator, and how is that different from the original alternator? In a nutshell, a one-wire alternator regulates the voltage internally. Essentially all we need is one 8-gauge wire to go from the positive terminal of the alternator to the positive terminal of the battery or in this case the positive terminal of the starter solenoid. As you can see, the spaghetti monster hanging off our factory alternator works to maintain voltage with the car’s external voltage regulator, which is a small box mounted in the front of the engine bay. One of our favorite things about the one-wire system is that bypassing the external voltage regulator not only significantly cleans up the wiring in the engine bay, but also, hopefully, introduces some more reliability into the system by removing another failure point of 60-year-old analog tech. An easy win-win by installing this one-wire system from Powermaster.
After installing the new Powermaster unit, the car lit off without a hitch and immediately settled in and began charging at right around 14 volts consistently. Even while stress testing the system with the engine hot, the fuel pump humming away, the accessory fans on full blast, the radio on, and even charging a cell phone, the system never faltered.
Make sure your ground and battery cables are cleaned. If your battery and cables have any corrosion as this one did, it can be remedied quickly with a solution of baking soda and distilled water. Once everything is removed and clean you can install the new alternator. All the wiring you’ll need is a new ground cable and a positive cable going from the positive terminal of the alternator to the positive post on the starter solenoid. Lastly, make sure the belt is tightened properly and you’re good to go!
There are a plethora of other one-wire alternators available for the Ford small-block, but the Powermaster is unique for a couple of reasons. Number one, they provide a small handwritten card verifying its performance. Powermaster guarantees the alternator will provide 102 amps at idle, 140 amps in the midrange or what they call “cruising,” and 165 amps peak at the top end of the rev range. Peak output is nice, but this low-rpm and midrange performance is where most of the work is done. Combining that with Powermaster’s excellent build quality and stellar customer service this was a no-brainer.
All in all, Powermaster’s Street one-wire alternator is an excellent upgrade for anyone looking to improve the capability of their charging system in a classic vehicle.
