88 mustang voltage question?

[Fantly45]

I have underdrive pulley system and I know that its going to affect the voltage but when I am driving at night and stop at a red light with the turn signal on it really pulls the volts down. I wanted to but an electric fan it and thought I would need more consistance voltage for everything to run right. So yesterday I put a 100 amp alternator in the car it still seems to be bout the same issue. Do i need a smaller pulley to make it turn faster or should I look in to a better battery. there is a duralast batt in it now. Any tips or info?

[wick]

Did you check voltage across the battery with the engine running? Did you do the 3G upgrade or just a 100 amp fox alternator? You may need a smalley alternator pulley to spin it faster. Especially at idle. I had underdrives on mine long ago. Had the same issue. I tossed them in the garbage can where they belong and never looked back. In the real world, you gain nothing from them except a fancy set of pulleys.

[crazylou]

u can get a smaller pulley for it from march performance, i went through the same thing or just throw ur underdrives over the hill...they really dont do that much for u anyways....

[lib88stang]

I sold my underdrives, they do nothing, car ran the same with stock ones and my turnsignals work great