just put on my crank pulley...... love it... car feels lighter, rpm is quicker, feels like the car has a lot less lag.......i love it...

 

i'll throw in my 2cents with my experiences with the udp on my 4th gen maxima. i felt that it did help with engine response. in terms of actual 1/4mi performance there are many factors in getting quicker times, but for what it's worth i personally believe the pulley is good for hundreths of a second on ave for those looking for that personal best. there are other things you can lighten which can yield more dramatic changes like wheels and flywheels. this mod should be one the last to get. improved engine breathing and ecu tuning offers more bang for the buck. i wonder what the privateer jdm engineers do in terms to fine tuning VQ performance especially those doing top speed runs in the VQ35DE.

 

because pulleys don't produce HP, they only easy the stress on the crank

 

with regards to the UR pulleys
i believe they are both Underdrive and lightened pulleys

 

They would never put an UDP on the race VQs. Check out the race spec VQs, SRs, and the like. They ALL have fluid damper style crank balancers. These setups weigh about 2X as much as the OEM crank pulley, but they offer superior crank dampening and valve train operation. I don't think you'd ever find a power train engineer say that a lightened non-dampened pulley is a good idea on any late model engine.

 

Actually it's the exact opposite. The pulley remove the dampening from the crank and increase crank resonance and vibrations.

 

 

The engine will certainly rev quicker, in neutral. But in gear, there is virtually zero effect (assuming your pulley is just lightened, not underdrive). Sorry, it's all in your head. But as long as you THINK it's better, that's all that really matters, right?

 

so its awaste of money

 

That all depends on who you ask.

Me personally, I think it is worth the money, and installing it yourself is a good way to learn more about your engine.

Dave

 

I,m not mess with 40,000 car

 

Ok, your loss. My mechnical skills are enough that I trust myself to do things like that. Your mileage may vary.

Dave

 

It doesn't matter who you ask, it's a fact that it's not "freeing up" any noticeable power in your car (under 1 hp in the higher gears). Check out my link if you have any questions about that.

But if a quicker revving engine in neutral is something you want, and don't mind the downsides of a likely lower engine life, then it may be worth it to you. Heck, if someone could hypnotize me and convince me that my car was faster, I'd probably pay $200+ too.

 

Really? Thats interesting. "Fact" must mean something else in your dictionary.

I've seen dyno sheets that show more power, and I've seen dyno sheets that show nothing. I know in my 300ZXTT I had a dyno sheet that showed gains of +10 hp and +8 ft-lb's throughout the rpm range. Of course, we all know that dyno sheets can be adjusted quite easily.

It's definitely debateable whether it "frees up" power or not. My opinion is that anything that decreases parasitic loss by being both lighter, and underdriving the accessories is going to work. You are welcome to believe anything you want, but I'd certainly be careful before calling something a "fact"

Dave

 

There's nothing magical or uncertain about it. Based on your engine's power curve and your vehicle's mass, you can determine how quickly the car will accelerate in any particular gear at any particular RPM (basic high school physics, force = mass * acceleration stuff). The acceleration of your car is directly coupled to that acceleration of your engine (change of RPM versus time), and thus you can determine the angular acceleration of any rotating mass attached to your engine (like the crank pulley), and thus the torque required to accelerate that item in any particular gear at any particular RPM. Now make the same calculation for the lightened item. Subtract the two, and that is the "freed" power. That's it, there can't be ANY more power gained from lightening that item unless you can explain where it is magically coming from. I go through all the math details here: http://www.stanford.edu/~mpg/lighten...omponents.html If you're not interested in the derivation, you can skip to the bottom for an example calculation for a lightened crank pulley for another engine.

But even if you're scared of the math, just use some intuition. Imagine your big massive car (3500+ pounds). Now imagine the acceleration you feel from your original engine configuration. Now take your small little 10 pound crank pulley and remove a couple pounds. Do you really think that this is going to free up so much power that you're going to FEEL a change in acceleration of your massive car? Ridiculous.

Dyno to dyno variations, temperature changes, etc account for any dyno evidence of purely lightened crank pullies. Lightened flywheels free up some noticeable power in 1st and 2nd gear due to the large changes in inertia (big diameters, big mass changes), but even lightened flywheels make little to no power in the higher gears once engine acceleration gets small enough.