The crank is balanced with the pulley and flywheel on it to provide a true'r balance, remove the pulley, you have obviously affected the balance. This what the hi ups at Infiniti say anyway. Take it for what it is worth. Much as the theory of cutting rotors on the car as opposed to off, same kind of theory.....

Infiniti Gearhead

 

say what? its balanced with the flywheel on as well? can anyone prove either that it is balanced with nothing on it, or that it is balanced with pulley and flywheel on? once and for all. SOLID proof so we dont have to keep going in circles. someone take a trip to a Nissan factory or something. maybe ill see if i can when i go to japan this summer. we need a conclusion to this.

G35s6mt/TSecu/350Z Springs&Struts/JWTpopcharger+Z-tube/StillenDualExhaust /6WireGroundKit/KinetixHighFlow

 

LOL< Never been to Japan, I am going by what the engineers from Infiniti told me in Atlanta. I tend to believe them. Just relaying the information on here

Infiniti Gearhead

 

Here's some profound insight from Q45Tech.

http://www.nissaninfiniticlub.com/fo...ghlight=pulley

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

Dude,
Hats off to the guy, that is so funny. Wonder if he can come up with a gear drive assy for the J30.....The guys in the shop got a good smile from that one............Thanks Catatafish

Infiniti Gearhead

 

well, i started this post and have installed the pulley mod since the post. i'm having a minor issue(if you want to call it that). for the past 2 days, the first time i start the car up the belts are making a loud squeking noise.. the pulley and belts were installed by the infiniti dealer, has anyone had this happen to them and what is the fix if there is one?

 

Stupid question here but are the belts tight?

Infiniti Gearhead

 

it only happens in the morning, and so far that is it, i'll check! the dealer installed them??

 

Usually thats when they will squeek, then as they warm up they will start grabbing. Maybe put a little more muscle on tightening the belts

Infiniti Gearhead

 

i'll call the service rep and let her know, have them tighten them!!! thanks for the info...

 

This has happened to a few folks from the threads I've seen. i believe tightening has helped. I had one belt get chewed from rolling into the rail upon install and found that it's a good idea to try out a couple different belts. Try another brand if the tightening won't work. And always carry an extra set around as the size you will need will not be in stock at your dealer and may be hard to come by in a hurry in a bad situation.

Good luck...

2003.5 DP 5AT Sedan (E-thing but Nav)
14.2 @ 97.18
Injen CAI
10 Wire Hyper-Ground
Crawford Plenum (V4)
UR Crank Pulley
Polk ex-3500 Tweeter Upgrade/Shock Sensor/H-Liner Under Hood

 

<blockquote><font class="small">In reply to:</font><hr>

Remember ever engine can double the generated HP the question is how many hours [minutes] it will last?


<hr></blockquote>

That nugget was in 1 of the above links by the Q45 guy. Struck me as interesting....he has always provided valid info on the other forums.


03 6MT coupe, red/willow, premium, aero, splash guards, alum pedals, clear corners, double 15% tint

 

<blockquote><font class="small">In reply to:</font><hr>

Remember ever engine can double the generated HP the question is how many hours [minutes] it will last?


<hr></blockquote>

That nugget was in 1 of the above links by the Q45 guy. Struck me as interesting....he has always provided valid info on the other forums.

<blockquote><font class="small">In reply to:</font><hr>

Still, I wonder if the pulley was the cause, or will we see more problems at 30K on hard driven cars.

<hr></blockquote>

lol, the moded cars ARE the "hard driven cars". People like to test out the mods after they get them! ....no one puts on engine mods just for the looks! (like neff)



03 6MT coupe, red/willow, premium, aero, splash guards, alum pedals, clear corners, double 15% tint

 

So, what you're saying is, don't mess with any of the pulleys?

2 G or NOT 2 G, there is no question!

 

After quite a bit of researching, reading and speaking with people who have rebuilt and blueprinted engines for a living I’ve been able to gather some useful information, which I’ll be using to make my decision about the UR Underdrive Pulley. My thoughts on this whole debacle are listed below.

First, I have a pretty good understanding of Physics. As I’ve stated before I graduated from UCF with a BSME in 1998 and have been working as a Senior Research Engineer in the Precision Mechanical Design group at Lockheed Martin Missiles & Fire Control, Orlando for the last 6 years. Given my educational background and the fact that I work with an amazing group of people who are extremely knowledgeable about dynamics, engines, design, machining, assembly and testing, the information I’ve been able to gain is not prejudicial or irrelevant in the least bit. I’ve spoken with more than a few of my co-workers about this issue and will include some of their comments below. Enough about me, on to the Pulley issue…

My take on this issue is actually pretty simple. If the crank is internally balanced and the pulley is also symmetrically balanced about its rotational center, when the two of these items are assembled they will be “statically” balanced. When the crank pulley rotates on the crank without any belts attached, the system should be “dynamically balanced” as well. The accessory belts are not rigid bodies and cannot be easily modeled in a computer to get “good enough” dynamic or harmonic measurements.

After speaking with an engineer who works in our Dynamics Lab, I was lead to another gentlemen, Gary, who worked on the “BO LAW” drag racing team for a little over 5 years. After speaking with Gary, I learned a thing or two about engines, cranks and pulleys that I had not really thought of, nor had I come across in my search on the Pulley Debacle. This person has built and balanced many engines. He has built 3000+hp diesel dragsters in the late 60’s and early 70’s and rebuilds the engines on old Chevy Nova’s as a past time hobby. He also works as a lead test set-up engineer for dynamic analysis of extremely sensitive optical systems, missiles, bombs, etc... The following is a loosely worded description of his explanation of a standard pulley set-up according to Gary.

“If a pulley is balanced about its rotational center and it is applied to a crank that is internally balanced you’ll be fine in an ideal world as far as not hurting the bearings. If the pulley has a rubber ring on it be careful. The rubber ring is used to dampen out the harmonics of the belts. Belts are not rigid bodies and they are constantly changing length and tension. They get a very slight amount of slack in them at one point in a single rotation and then they get more taunt a split second later. This happens on a constant, random basis depending on the engine loads and other variables. These variances cause loads to change, which translate into harmonics, which are bad for the bearings. The job of the rubber ring is to dampen out these harmonics (or unwanted frequencies). This ring is actually absorbing the vibrations caused by the belts and is not allowing those vibrations to be seen by the crank or the bearings (this is a very good thing). If the lighter weight pulley were designed to have this rubber ring, it would have to have a larger rubber piece than the stock pulley does, since the aftermarket pulley itself is lighter. The stock pulley, being heavier, also helps to dampen out the harmonics from the belts, which help preserve bearing life.”

He also said, “today, most precision machined parts can be designed and manufactured so that an engine can be built without having to have a pulley on the crank to balance an engine. Most 4 and 6 cylinder cars are designed like this (something to do with a 120-degree orientation of the engine internals… I got lost here). Older 5 and 8 cylinder cars often times have pulleys that are asymmetrical, or have counter weights designed into them. This way they can take one stock pulley off of a car and add another stock pulley without having to rebalance the engine.”

“For the added benefit of 2% to maybe 3% performance gain, I personally (still Gary speaking) would stay away from any pulley system and look into a performance chip that adjusts the ECU. If you started having problems with your bearings, this would just be the first of many expensive repair bills as a result of the damage to the engine.”

I absorbed all of this and took some quick notes, as I didn’t want to forget anything that Gary said.

As some of you might understand, there is this other half of me that says there are plenty of other people with UR Pulleys on Nissan Maxima’s with the same VQ35DE who have many miles on their engines. They have allegedly reported no sign of bearing wear, engine damage or anything remotely negative, so why should I worry? Also, there are people who have installed the UR Underdrive Pulley and they are doing Black Stone Lab. Oil analyses and are not seeing elevated lead content in their oil, so their bearings must be fine, right?

The mod hungry side in me is trying to justify adding the pulley, but the logically minded side is saying, “listen to the Physics, they don’t lie”.

As recently as this afternoon I was ready to install this pulley, going back and forth between shipping back the box to Performance Nissan and going ahead with the install. The bottom line for me will be reason and logic. I will be sending this pulley and belts back to Performance Nissan and getting my money back (less shipping charges of course). The small performance increase is just way too low compared to the potentially staggering costs relating to damages with might occur, if I were to install this pulley. Couple this to the fact that my local Infiniti dealership is vocally not mod friendly, so I’d be 100% out on a limb should anything bad ever happen.

For anyone interested I have a brand new pulley bolt that I ordered from Orlando Infiniti that I’d be willing to ship to you if you pay the $5.75 and shipping costs.

Good luck to those of you who have the pulley or are still planning on doing the install. I wish you all well and many untroubled miles with your G’s or Z’s.

Thanks for reading. -Neffster

Oh, redwillow why don't you head out to Bithlo this Friday (5-7-2004) and see how easy I take it on my G. [img]/w3timages/icons/wink.gif[/img]

300bhp??? We'll see... 5-22-2004