Are they a worth while upgrade? What kind is better to get? How do they work? Im looking for a little more power... especially low end if thats possible.. Thanx.

 

The ones I have seen are aluminum. They will work for a while but need to be replaced often. They are made of a hard coated aluminum (anodized). Once the hard coat wears away they will wear rapidly. If you can find them in steel they will last much longer. The tradeoff here is light and cheap to machine with many colors available. They will also reduce the parasitic loads from your accessories. Sometimes they can cause overheating problems. They also reduce alternator output so that sub amp may drain the battery. -Always tradeoffs!

 

I have the March Power&Amp(steel) pulleys on my Lightnings and have had no problems.I tow with them and haven't had the first charging or overheating problem.They are a good "bang for the buck" mod in my experience.

 

it depends on what your putting them on. if its a 4wd i would say no. because when you wheel its usually at low speeds and low rpms which would cause heat issues and low alt output. but on a mustang or 2wd truck thats meant for speed then you may see some gain.

 

I've been running the Ford racing steel underdrive pullies with an ASP overdrive alternator pulley for over two years with absolutely no wear on the pullies or cooling/charging issues to speak of even towing heavy loads in 100+ temps.

 

like i said on a 2wd rig doing normal/towing driving is not a problem. its only when 4x4in at low rpms or going real slow for long periods of time that you would have an issue. for a 4wd to gain what underdrive pullys do is to install some electric fans and junk the stock fan system.

 

Kemicalburns , my post was not intended to be a flame on what you posted, I was just posting my "personal" experience with underdrive pullies, Electric fans are an excellent upgrade too

 

I have a set of March pulleys on my 95 4X4 and have had no problems. I gained HP and mileage. The hardest part was getting the right size belt. I would do it again.

 

I also ran March underdirves on my 90 F-250 4x4 and 94 Lighting (when it was N/A) and didn't have any charging or cooling issues with either. However, if you had any cooling issues with an underdirve set up, then you could install and water pump pulley from a mid 90's cobra. It'll spin the water pump faster to help keep the engine cooler at idle and/or low engine speeds.

 

Wear issues usually only occur with aluminum pulleys. Steel pulleys can become polished or glazed sometimes when belts slip. I have seen a few steel and cast iron pulleys worn out but they had been in use a long time.

 

Is there any way to keep the alternator spinning normaly while underdriving the other components? I have two amps, a 150 watt x 4 and a 600watt sub amp, so this would be a concern for me.

 

^^^ Yes , get an overdrive alternator pulley from ASP. ^^^

 

The only thing I noticed with the underdrive pulley on my truck is below 1000rpm the alt isn't charging (barely holds 12 volts) but my truck rarely idles, and has an elec water pump so that isn't an issue but if you do a lot of stop, and go driving in heavy rush hour traffic I would not recommend it. as that is were the problems mentioned by people here will REALLY make themselves known

 

I checked the alt. output on both of my trucks after installing the power&amp pulleys.With the headlights on high beam,the a/c blowing on high,c/d player on,I got 13.5 volts at idle.

 

You need 13.8-14.2 to charge the battery. The voltage on your rig should increase when you drive tho so it is probably fine. Measure it at 1000RPM and 1500RPM to make sure. Most of the time you won't have all of that stuff on like that at the same time. If you have an electric fan and it kicks in that voltage may drop too far at idle. A big amp would also draw down the electrical system.