Pulley Sizing and Pulley Ratios- The majority of alternators on the market have a maximum rotor speed of 18,000rpm to 21,000rpm. Exceeding the maximum rotor speed can damage your alternator and result in costly rebuilds, but to insure the best low-speed performance out of your alternator you want to be sure that your unit is spinning as fast as possible at low speed. This is where proper pulley sizing becomes critical. To determine your rotor speed you need to know 3 things: 1. Crankshaft pulley diameter 2. Alternator pulley diameter 3. Maximum engine speed (redline or rev limiter). To calculate pulley ratio simply divide the crankshaft pulley diameter by the alternator pulley diameter (Ex: 6” crank / 2” alt = 3 for a 3:1 pulley ratio). Now to calculate the rotor speed you divide the crankshaft pulley diameter by the alternator pulley diameter, then multiply the result by your maximum engine speed (In this example we will use a 7,000rpm max engine speed. Ex: 6”crank / 2” alt = 3. 3 x 7,000 = 21,000). New cars have lower idle speeds these days, many under 600rpm while having a 7,000rpm+ redline, making it vital to determine the proper pulley sizing to insure that the rotor speed fast enough for good low-speed performance while preventing damage from excessive rotor speed. Underdrive pulleys can slow down the rotor speed causing very poor low-speed and creating the need for smaller alternator pulleys. Smaller pulleys also offer less belt traction and if too small will reduce the output of your alternator due to excessive belt slip so calculating the proper pulley size is very important. Overdrive pulleys like those used on supercharged cars such as the Ford Mustang Cobra, Pontiac Grand Prix GTP and many others can spin the alternator too fast by altering the pulley ratio. On these cars you may need a larger diameter pulley to prevent alternator damage, but this isn’t a bad thing as it increases belt traction for your high-output alternator.

This is the Mechman TJ, it's a 1997 Jeep Wrangler TJ with the 4.0l inline-6 engine. We equipped it with our 270a bolt-in alternator kit with our AVBM adjustable voltage, 2 XS Power S1400 14v batteries and wired it in with Shok Industries cable. We run 14v in our vehicles with great results. Brighter lights, faster windows, overall improved electrical performance from your vehicle will be the result. Louder stereo, longer play time for audio people, higher voltage with less drop for the racers. While we have done this for our vehicles with great results keep in mind that you do this *at your own risk*. Here's a short video of the Jeep, more to come as we continue the install. It's getting a sound system, winch and maybe a couple other accessories to complement the work that has already been done.

We at Mechman Alternators stand behind our products and want to show it by increasing our warranty to TWO YEARS. The TWO YEAR WARRANTY applies to ALL Mechman Alternators sold ON or AFTER 07/13/2011. The TWO YEAR WARRANTY covers defects in materials and workmanship including replacement parts and labor for a period of TWO YEARS from the date of purchase as shown on your original invoice. We do not cover repairs handled by the owner, other shops or other persons or businesses without the express written permission of Mechman Alternators. This warranty will be VOID if the unit is physically abused, misused, improperly installed, or is not used in the original application. This warranty is NON-TRANSFERRABLE. You must include a copy of your original invoice to receive warranty service. The customer is responsible for sipping to Mechman for warranty service but Mechman will pay return shipping back to the customer in the case of a warranty repair. For those of you who have a Mechman unit that is out of warranty (or other brands for that matter!) please remember that we offer discounted rebuild services on all of our Mechman Alternators as well as other brands of high-output alternators. Thank you, Mechman.

Many car audio enthusiasts eat, sleep and breathe speakers and amplifiers. Other installers get excited over the new advancements in car alarm technology, GPS systems, and other creature comfort upgrades that they can program, wire, and tailor to their own use. Few car stereo fanatics, however, get quite as excited about what actually makes all of these things come to life: the vehicle’s alternator. The alternator is the heart of the entire vehicle’s electrical system, pumping precious current to the battery(s), amplifiers, and other accessories. The biggest, loudest, and most elaborate mobile audio/video installations can never function to their potential without being backed up by a properly sized high output alternator.

Automotive manufacturers operate on a budget, just like any other company. When a vehicle is in the design stages, automotive engineers are pressured to equip the vehicle with the smallest, lightest, most inexpensive alternator that could possibly run the vehicle’s stock electrical system. It is for this reason that an OEM alternator is almost NEVER up to the task of powering any electrical equipment other than what was equipped on the vehicle from the factory. Adding aftermarket electrical accessories, especially amplifiers, without increasing alternator output is dangerous for both the equipment, and the vehicle! When more current Is being consumed by the vehicles electrical components, than is being produced by the alternator, a drop in voltage is experienced. The greater the deficit of amperage, the greater the voltage drop will be. Most amplifier failures are a result of being operated below their recommended voltage.

A properly engineered high output alternator is the only way to keep voltage levels in the proper range. Adding batteries helps to stabilize system voltage, but they still need to be backed up by an alternator that is capable of replenishing the current that is being used by the audio system. In addition, most Mechman output alternators can be ordered with adjustable voltage, which allows the customer to not only keep up with the amperage requirements of the system, but to actually increase system voltage to improve the battery(s) state of charge, as well as amplifier efficiency. Today’s amplifiers commonly put out 20 -30% more wattage at 15.0 volts as compared to the voltage achieved with an insufficient alternator. Countless SPL competitors have seen immediate gains in loudness with a simple alternator upgrade.