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Old 06-08-2009, 01:41 PM   #94 (permalink)
wstar
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Location: Houston, TX
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Quote:
Originally Posted by imag View Post
One other con that should be mentioned - you won't get as much current to your battery through the alternator (underdrive means lower belt speed). This is probably only an issue if you have a high-current audio system.
This is only true at idle though. Once you bring the revs up to driving speed the alternator is still getting more RPMs than it needs (which is why they have clutches) to maintain the proper output. Even at idle, I don't think you're actively draining your battery or anything, just not charging it as fast

Perhaps if you have a truly monster audio system it might be a concern. I don't, and I haven't had any issues with the UD pulley as far as voltage is concerned though, and I've had mine on for quite a while now. I also switched to a tiny PC680 battery mounted in the trunk via a long cable run. Even then, I still haven't had any problems starting the car, or any other electrical issues.

Quote:
I assume the lower speed to the power steering pump doesn't make any difference...
Right, the other two minor points for potential concern for the UD pulley are the AC and the Power Steering. I haven't had any issues with either. The change to the power steering isn't really noticeable, and again even if it were, it would only be at low rpm rolling around a parking lot. AC is fine too, still blasting ice cold air in the Houston heat.

In short, there really are no cons, unless maybe you have very demanding electrical needs at idle.
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