Ok, I am thinking of changing out my crank pulley or possibly all of them. I have been doing some research and found that the UR pulley weighs 1lb and you have to get new belts and the KJR weighs 2lbs w/ stock belts. The UR pulleys can cause some underdriving (15%), which could cause some electrical parts(A/C, Stereo, etc) to operate slowly while the KJR pulley does not have underdriving. As for gains, It is said that for every # of engine weight loss, you gain 2.7 hp. Our stock crank pulley weighs in @ 6lbs. So KJR is offering 7-11hp and UR is quoting 10-16hp Not including any other mods of course. Can anyone help me out w/ which one is the best? or does anyone possibly have these installed? or even some Dyno Charts?

 

+1 for UR - no dyno chart, but butt-dyno reports a better launch from 1st.

 

Ok, Thanks, but does anyone have the KJR pulleys installed? And also should I be worried about Underdriving?

 

Granted I don't have a massive system, but with 2 amps, I've never encountered any dimming or charging problems. I wouldnt bother with the KJR. There's alot of pulley controversy out there - is it bad cuz of underdriving or harmonics - blah blah... thus, if you decide they're worth it, might as well go all the way.

 

i also have 2 JL 10s w/ a 400 watt amp. in addition I have a 7'' xenarc screen and dvd player. I also run/charge my ipod and used to run a GTPro SS device both off my 2 cig. lighter adapters. Running ALL of those things and having headlights, wipers and heat on without ANY problems. Thats a whooole lotta **** to run meanwhile underdriving. point is there isnt really anything you need to worry about unless your competing for an SPL competition to hit 130-140 dB w/ a 1000-2000 watt sound system w/ 10-20 monitors...

 

^ Well he did start with the chromies, so you know the 15 monitors are coming next

 

^Damn right, I cant even miss an episode of Family Guy and the Boondocks

 

what exactly do pulleys do? ..faster acceleration? ...

 

dont believe the adds about horsepower increase cause there is none.what it does do is allow the engine to rev faster thats it.also you might want to do a bit of research cause a lot of the z owners are having front crank seal leaks cause of the pulleys.underdrive pulleys will free up a little power.stock size light pulleys will not.

 

+1

Also, if you're looking at going FI - stay away from them entirely. The minimal gains (if any) aren't worth the money or headaches.

 

Ur all day.!!!

 

WHAT THE FREAKIN HELL lol...

the resurrection is complete.

 

I haven't research this that much, but i can't recall a thread of some signicant gain from this. If anything, people always say "blah blah..pullies gain won't show on the dyno..blah blah" sounds like denial that they wasted their money to me. Every pully thread always starts with the OP posting about the weight saving and in theory x lbs = x hp this and that. I'm sure that's what the manufacturer want you to read also. But I haven't yet seen solid gain on pully on a dyno. I always thought the point of pully is to underdrive it to get the gain. I don't believe in the whole weight reduction theory only.


~Khoa

 

no amount of gains will negate the 1000000lb weight from his chromie painted spinners ,
I vote for Ur too, theres more prositive threads about it

 

All these performance parts for him and he still wont ever get under the 14s