Steeda Underdrive Pulleys 10 GT???
 

Hey guys, I have been reading about performance gain by using the underdrive pulleys on the 3v. I remember wanting to do them on my 2v a few years ago but was scared after someone told me, that my A/C would not blow as cool and my lights would dim. Now Ive heard that was a problem on the 5.0 but what about the 4.6 in the summer or winter, are these hard on the car? Will they throw anything out of whack? And lastly would I need to get a tune sent to my Xcal?

Underdrive pulleys cause no issues on a properly operating vehicle.

On my old 96 Cobra it had underdrive pulleys. After 6 years with them one day the lights started dimming at idle at night. That was because the alternator output deteriorated from when it was new and not caused by the pulleys themselves. A new alternator solved the issue.

You are right that pulleys causing problems was a 5.0 thing. On 96-newer vehicles that are in good condition there are no issues with them whatsoever.

Gus

I hate pullies and will NEVER have them on another car! Just as someone told you the a\c doesn't spin fast enough, the alt. doesn't spin fast enough, and the powersteering doesn't spin fast enough. The car will run hotter because the waterpump spins slower. The alt. is the worst as the light do dim at stop lights and the car will kinda idle slower. They just suck! Worst money I ever spent!

Again, this "may" have been an issue with older cars...I never experienced these issues with 3 previous Mustangs I owned ('88-'90). For the newer Stangs, UD pulleys are a proven performance bolt-on.

I agree UDP's will only make existing problems you already have more evident. I have put UDP's on almost every car I have owned and plan to with the Mustang too.

Steeda posted a dyno with a 10rwhp gain from just their UDP on their 2010 GT. I plan on getting them after I get my intake and tune.

Ok...from what I understand from reading just about every post in this section for the past three months is that a tune is specific for your PCM and mods also. Dosn't this mean that you should order your tune after you install UDP's? Or would you get your tunes updated/rewritten from whomever you got the tune from? Does this incur added costs? I'm not trying to be a smartazz, just trying to learn.

I put on the Steeda UDP and it dyno'ed 7.5 HP gain

I've owned 4 Mustangs including 5.0's and have had underdrive pulleys on all of them. Won't own one without them (unless it was supercharged of course).

I'm even about to put one on my 2008 Mercury Milan. If they make one for a car I own, it gets a set. Pulleys work.

Underdrive pulleys do not require any type of tuning. All they do is reduce the load drawn by the accessories to run them leaving available power to drive the rear wheels.

Hmm. Hadn't thought of it that way. Thanks Gus