By the way, I was looking at the light-weight pullie, (not the ud pullie) and was wondering if you're seeing about 8-10HP from the crank or to the ground. I'd be uber impressed (and probably still skeptic) if it were to the ground.

BTW, hate to dig up a dead horse to kick, but have you seen then RST-V8 putting out 500BHP? 2.4L weighs 90Kg dressed! Talk about power-to-weight! <-- I'd take one of these over a plastic motor any day.

Crash, this thread may interest you if you haven't seen it already: http://www.the370z.com/engine-drivet...-dyno-vid.html

Cool... Looks like if the U/D pulley is gaining 5+whp, the lightened wheel would gain maybe 2-3. Doesn't seem worth it.

Thanks. Hadn't seen that thread.

Power isn't everything and that isn't the function of a flywheel.

true dat!

We're talking about pulleys in this thread, not flywheels.

HAHA... Exactly. I was thinking, "I didn't say Flywheel, did I?"

Believe me, a lightweight flywheel makes a big difference. If you're making serious power though, it becomes the weak link in the chain. For 450BHP and down, lightweight flywheels are great.

But as far as the pulley goes, it's not going to make enough difference when you're still close to stock power. Spinning mass is serious business, but when you're only gaining 2-3 HP to the wheels, it's not worth it. An underdrive pulley is different, though.

so what are the pros and cons of the underdrive?

pros - more hp, possible faster rev climb (not sure this is confirmed)
cons - none we know of except potential dispute with nissan next time you bring it in for warranty... or extra work to swap back before you bring in for warranty

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. I assume the lower speed to the power steering pump doesn't make any difference...

It should also be mentioned that if you intend to install a supercharger in the future, you don't want an UD pulley, as superchargers are belt driven. Although you could swap it back out if you install a supercharger down the road.

no i meant as like compared to the light weight pulley

Those ARE the cons compared to the lightweight pulley.

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.

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.

^^ So no vacuuming the house on the car's power parked in the driveway? :D

quick question, is it possible to get both the underdrive pulley and lightweight pulley installed on the car?

by virtue of being underdriven, the underdrive pulley is smaller and lighter than the normal lightweight pulley. So no, they replace the same part and the underdriven one is smaller and lighter.

Got my stillen lightweight crank pulley put on and was wondering if n e one would kno why the engine makes noise now when it down shifts at times goin downhill and a little bit when i get high rpm's??...its kinda like a hissing sound..sounds like the belt but its suppose 2 use the stock still..thanks