View Full Version : about underdrive pulleys

06-04-2004, 01:26 AM
is it worth getting the underdrive pulleys and what is the main reason for doing this? thanks for the help

06-04-2004, 05:35 AM
They spin the water pump & alternator slower, thereby using up less of the engine's horsepower. Drawback is that the slower spinning components can be overworked. If you have an aftermarket stereo system with a large amplifier, the stock alternator can get overloaded. Likewise, if your engine is making a lot more horsepower than stock, it generates more heat. The water pump "could" have a harder time cooling the engine sufficiently.
From what I've been told, it's a nice mod in the later stages of your mods. That means there are other less expensive ways to gain more horsepower first.
Hope this helps.

sho taurus
06-04-2004, 06:10 AM
they slow down your accessories and gives you few more hp.really you get most power from your switching crank pulley.all my mustangs that was the only one i switched,any couple years ago i did my sho's.water pump and alt. and crank and i wish i didn't do those.cuz now if i sit in traffic,car doesn't run hot but it warms up alil and also i have nice stereo in it and sitting at a light at night time with boom box going my lights get dim.really just need the crank.if i do my super coupe that is only one i'm putting on.and the companies always say you get 10-15 hp.they dyno'd mustangs before and after and if i remember right it's like 4-7 hp.and i know the k&n panel filter blows it only gives you 1 hp in dyno.and in i think it was like 8-10,000 miles a regular paper filter flows more air.even after you clean one paper flowed more. remember i said panel filters not cones.ya but for cheap few hp do the crank pulley.leave the other 2 off.i wish they just sold the crank pulley.

06-04-2004, 10:02 AM
The water pump "could" have a harder time cooling the engine sufficiently.
Last time I checked, it was the radiator that cooled the engine.

I have underdrives on my car. I think they are over rated. I knew that when I bought'em, so I'm not sorry I put'em on.

I have a bunch of mods on my car (14.250 @ 97.6) and have never had an overheating problem caused by the pulleys.

The Alt. has never had a hard time keeping up with my electrical demands. I currently have a smallish stereo, but will be adding a big amp & sub soon. I'll see how the the Alt. acts then. I'm not a Boom Guy, I just like ACCURATE low bass. I don't anticipate any Alt. problems, even with the big amp (Kenwood KAC-929).


David Neibert
06-04-2004, 12:37 PM
I've had ASP underdrives on my SC for about 3 years and there were no negative issues with cooling or the charging system from the pulleys. I think they are one of the best bang for the buck mods you can do to an SC.


06-04-2004, 01:41 PM
Last time I checked, the water pump pumps the water through the radiator.

06-05-2004, 03:23 AM
Last time I checked, the water pump pumps the water through the radiator.

um no, the water pump cools your windshield on hot days with those jet thingys , the underdrives are great because i dont know how to drive a 5-speed and keep the RPMs revved up like the ricers do and Im always burning up the P/S fluid, this way I only change it once every 2 months :)

06-05-2004, 05:24 AM
Ah, then you shoud get some of that higher octane power steering fluid!