Quote:
Originally Posted by brickyardz
Your looking at 2 completely different things. The idler pulley is usually the one putting tention on your belt. If that is bad and needs to be replaced you should get it done. Getting an underdrive pulley set will not include an idler pulley.
The underdrive pulley set you mentioned replaces the crank, altenator and water pump pullies. It is true that by making them lighter than stock you have less weight on the crank and it does increase HP. Underdriving the other pullies (making their diameter smaller than stock) does also add some hp but can cause problems if you have aftermarket stereo equipment that is sucking a lot of power. The under driving will produce less power at lower rpms because the altenator isn't turning as fast.
Most of the power gains are in the lightened crank pulley. One day I plan to add these but you can also get a set with all standard sized pullies, no under driving, so stock belt size is maintained and you don't have power issues. The amount of hp you gain from underdriving is minimal so my choice, when I do it, will be to maintain stock size pulley and just get lighter ones.
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IM sorry but what do you mean by 2 different thinggs?? the idler pulley is just a pulley itself, and the z has a total 3 pulleys,,plz correct me im wrong. the auction is also offering 3 pulleys.