And on our engines, in case you were wondering, only the A/C, Alternator, and Power Steering are belt-driven. The only one that is really any cause for concern is the alternator at idle possibly not giving enough charge for your load and causing battery drain.

But... you have to consider that the alternator's output at idle is designed to handle every electrical load in the car all at once plus some aftermarket addons and then some safety margin as well. Unless you're installing a huge audio amp, and then running it at full volume with the window defrosters and headlights on, constantly rolling the windows up and down, with several amps of crap plugged into your lighter sockets, I don't think you have to worry about it.

Thanks for your short yet detailed explanation! Appreciated it.

Yes I agree I could have googled it, but coming from a consumer's point of view, I could not find any explanation from Stillen's webpage or from their initial first post on this thread. Which seems odd because how could a business can sell a product without providing even a small explanation on what the product does is beyond my "business imagination". I suppose the vendor expects us to google for it.

I come from a pretty modified Mini Cooper S background so I do have some understanding of what an under sized pulley will do for the Supercharger. And when I bought the undersized pulley for the Eaton supercharger, there was an explanation as to what the pulley does in terms of benefit. You know... smaller pulley = supercharger spins faster = more horse power to wheels = happy motoring days!

Anyways, after reading the wikipedia link, I have a better understanding of the pulley now and this product is probably better for colder climates not not for my equatorial country where I need the air-conditioning power! That being said, the stock sized pulley will be be the one for future consideration.

Yes, you should see benefits from the stock-sized pulley as it is lighter. Not as much as an underdrive, but you will still see gains. That's the one that RCZ is installing, so if you keep an eye on his posts you should be able to see what gains he gets from it.

Competition for Stillen?

http://cgi.ebay.com/ebaymotors/Unort...1%7C240%3A1318

Same price, free ground shipping. Slightly lighter than Stillen's stock size lightweight replacement.

Stillen: 1.32lbs

Unorthodox 1.20lbs

Thoughts?

Well, Unorthodox is at least a company I've heard of before, so it's not like you're going with a total no-name. I'd still rather have the Stillen unit. Seems funny to me someone's selling it for our car on ebay when the mfg doesn't list a 370Z application yet (although to be fair, even Stillen is using the same part number across the same range of applications). Also, the design of that pulley looks like it would be a major pita to remove with a puller (those little round holes), the Stillen one looks pretty easy. They also list our stock pulley as being 8.25 lbs, which is definitely inaccurate. Stillen claims the stock units are 4.72. I didn't weigh mine, but that sounds about right from when I removed it.

Unorthodox is not very happy with us, as we've developed our own line of pulleys after carrying theirs for a while. We had some issues we weren't happy with, and went ahead and now there is a line of STILLEN pulleys, including new applications like the 370Z underdrive and several others that aren't available from them.

You'll notice if you look throughout the internet that their stock sized pulley used to be over 1.5lbs a little while ago, and the price about $50-60 higher. I would imagine our design of the pulley being less weight has caused some issues for them, and while I haven't seen that pulley (which is identical in the looks dept to the one they have had) in person, I'd imagine it's easier to change your marketing materials and your price than redesign... but I do not have that info.

They also misrepresent the factory pulley weight in their (not for 370Z) mfg listings.

I've said before, careful with the ebay purchases.. you want to get something reputable, and ensure that it's coming from a reputable manufacturer.. but I have no idea about the ebay vendor, he could be extremely legit.

are these pulleys easy to install?

In your case, I wouldn't recommend trying it yourself (no offense intended). But a good mechanic shop should have no problem installing this quickly for you.

hehe not at all. i guess i'll order and get amplified to install these.