underdrive pulley question
 

With my underdrive pulley when i am ideling at a stop light or something with my headlights on and my cars in drive the dash lights dim and the battery gauge does down, then when i go it goes back to normal. if its in neutral theres no problem. is this normal and is it bad at all or what??? thanks:confused:

Yes.... it isn't unusual to have charging problems with an under-drive pulley. Specially if you have a 40% crank pulley, or a 25% crank U/D and a 15% alternator U/D. Several manufacturers also make an over-drive alternator pulley to minimize the problem.... but then you're giving up a part of the 1 or 2HP you might have saved with the U/D crank pulley :D

The problem is usually more pronounced on auto cars since stick cars generally idle higher. :)

Is it worth keeping it on or should i just have the stock pulley put back on?

If it is not giving you any problems (associated with the UDs) why not keep it? I believe that mine provides me with better throttle response, if nothing else.JMHO :cool:

I like better throttle response, but I am not willing to pay for it with electrical weakness. Has anyone attempted to alleviate the output reduction form the alternator by replacing the stock alternator with something a little bit beefier? Just an idea...

I just took mine off. I dont see a noticeable power gain out of it. If you want the same throttle response, just turn your A/C off.

Could someone please explain to me, in technical terms, what "better throttle response" means? The car is either faster, or it isn't. It can only be faster if its making more (or losing less) HP.

If there is less resistance to movement of the serp. belt due to accessories (smaller pulleys), I would think that translates to faster changes in engine speed. Some people would call this improved throttle response. It could also be interpreted as better power translation to the rear wheels from the crank. This is going on intuition, though, so it may be way off...

Actually, I only know what I believe it means to me.

E.g., when I installed a 52MM TB, I felt as though the larger opening provided "quicker" throttle response and therefore quicker acceleration.
Not referring to cruising acceleration, but from idle.

As far as my March 2-pulley UDs, I "again" felt that since the engine's rotating mass was not being burdened as much that the "rev responses" were a bit quicker and therefore providing quicker response when the throttle is mashed, in this case off idle or at cruise.

So in the case of the TB not more HP, but faster opening because of the larger blades.

In the case of the UDs, less parasitic drag which translates into more HP to the rear and also quicker response at the throttle.

Maybe I am all wrong here, especially from a technical point, however, I know my car and I may have imagined it, but I believe that both of these mods made my car more responsive. All I know is when I punch this sucker there is absolutely no hesitation.JMHO :cool:

I've been looking at purchasing an underdrive crank pulley. I've read a lot of posts about the pros/cons. A lot of people tend to point out that the gains are minimal, .7 horsepower according to WS6.com. What sold it for me was the gains in torque, WS6.com showes an increase of 5 ft/lbs. That makes it worth it for me. I will be curious to see if I do notice any increased throttle response when I finally get this thing bolted on.