Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Performance Upgrades - Maintenance - Modifications - Problem Solving - Off-Road - Street Trucks. Covering the Explorer, ST, Sport, Lincoln Aviator, Sport Trac, Mercury Mountaineer, Mazda Navajo, Ford Ranger, Mazda Pickups, and the Aerostar. Featuring H.I. - Human Intelligence.
I'm looking at replacing my alternator with a ~200A model.
At the same time, I was considering an underdrive crank pulley.
Should I be looking to put an overdrive pulley on the new alternator to compensate?
Join the Elite Explorers for $20 each year. Elite Explorer members see no advertisements, no banner ads, no double underlined links,. Add an avatar, upload photo attachments, and more!.
They're not sets - the underdrive crank pulley/harmonic balancer assembly is out there at a few places selling it for the 4.0L SOHC Mustang.
The overdrive alternator pulley appears to be available from a number of eBay resellers - I just need to determine which alternator I have, so I can determine which alternator I'm going to buy, and then buy the appropriate pulley for it.
If I install an underdrive crank pulley, then the alternator, power steering pump, AC compressor and water pump all run slower.
If I then install an overdrive alternator pulley, that should restore the alternator to "full" functionality.
I want to make sure that I'm not going to seriously hurt the power steering, AC compressor or water pump, and trying to gauge how much "less" of those accessories I'll have.
Be careful when purchasing a so called "200 amp" alternator. Some have lower output than the stock alternator at idle. Some use a small diameter pulley to achieve the higher output. Some don't supply the rated output when loaded. I purchased a so called "220 amp" alternator via ebay. I had it and my stock 130 amp alternator tested under load. My stock max output was 150 amps and the 220 amp alternator max output was only 160 amps. I returned it and had a 240 amp unit custom built locally: Alternator upgrade - 4G, 3G large or small case?
I had Mike Singer build me a 240A gem... I've had no issues with it and it pushes 820 watts of lights at idle with the system staying in the >12.5v range even after an hour of climbing.
I ended up paying about $450 on it, but I had him powdercoat it red too...
From Mike:
"The upgraded unit that I offer for your vehicle is a 230A. This alternator is a direct bolt on design for your vehicle and would plug in just like the factory alternator. I would consider this upgrade suitable for up to around 3K RMS if you eventually had battery upgrades to go along. I see this being the ideal addition to your vehicle in terms of being able to support your current draw now as well as in the future.
I include my overdrive pulley to boost the idle output (this will spin the alternator faster at low RPMS to boost idle output by around 30 to 40A more then the stock will). The total price on this unit shipped w/ my lifetime warranty on labor is 409.
All units come w/ a lifetime warranty that covers any repair labor (parts are at company cost) You can add a powder coating option on any order for an additional 48 dollars."
My custom built 240 amp alternator has a new 200 amp rotor winding, a new 240 amp stator winding, and a new load response internal voltage regulator assembled in a new case with a new stock size pulley. It was built for me by Tom Coker of Carolina Alternators. It was the first one he built and I convinced him to build for other forum members. I think he offers a 200 and a 240 for around $1 per amp plus shipping costs. So far mine has been very reliable.
It was built for me by Tom Coker of Carolina Alternators. It was the first one he built and I convinced him to build for other forum members. I think he offers a 200 and a 240 for around $1 per amp plus shipping costs. So far mine has been very reliable.
Went by a local business that claims to build custom alternators, and got rebuffed that they "don't do anything for that kind of stuff" and that they can really only do stock output stuff.
Honestly don't know why I even try to do business locally anymore.
Be careful when purchasing a so called "200 amp" alternator. Some have lower output than the stock alternator at idle. Some use a small diameter pulley to achieve the higher output. Some don't supply the rated output when loaded. I purchased a so called "220 amp" alternator via ebay. I had it and my stock 130 amp alternator tested under load. My stock max output was 150 amps and the 220 amp alternator max output was only 160 amps. I returned it and had a 240 amp unit custom built locally: Alternator upgrade - 4G, 3G large or small case?
Very true I actually run dual alternators and dual Optimas. My primary alternator is between 200 and 250 amps I forget exactly, and my secondary alternator is a GM ad244 i believe that I purposely bought with low amperage so that I would have good voltage at idle which is important with all the onboard electronics and even more so important with a snow plow. You really need that voltage at idle but like street rod was saying before if you go with an underdrive crank pulley and a high amp alternator even if you put a smaller pulley on the alternator you're probably still not going to see great voltage at idle. I think my secondary GM alternator is only a 90 AMP or a 120 amp, but both of my alternators combine make great amperage and it stays between a steady 13 and 14 volts at idle even under a decent electrical load and even if I'm only running on one battery.
However I'm looking for an overdrive crank pulley I thought I remember seeing one on the web somewhere. I wana spin the Eaton M90 on my BoostedXPLR Sport just a little faster. I already calculated exactly how much bigger I wanted the diameter to be so that it would only give me like one or two pounds of boost and that it wouldn't spin my accessories too fast plus like I said before I have smaller pulleys on both of my alternators. Maybe I didn't see an overdrive crank pulley on the web for the 4.0 sohc. I might have gotten in touch with a company that makes custom crank pulleys a long time ago and they might have given me a quote I forget. But if anybody out there knows where to find overdrive crank pulleys for the 4.0 that would be greatly appreciated.
