UR Pulleys & Harmonic Balancers - in general
11-04-2003, 03:20 AM
#61
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I've had my pulley on my car for almost seven months. It was one of the first mods I put on my car, and I've never had a problem with it.
But two concerns:
Why would you try comparing the engine of an airplane to that of a car? While in theory they both serve the same purpose, they are designed for two completely different types of transportation and I'd be a little bit more leary of trying to do anything to an airplane engine than a car's engine.
Second, science is always changing. For almost two centuries no one dared touch Newton's law of gravity, until Einstein came along with the theory of general relativity, which was then challenged by Bohr's theory of quantum mechanics, which was then challenged by string theory. If science didn't change then we'd still be driving around in Model T's.
But two concerns:
Why would you try comparing the engine of an airplane to that of a car? While in theory they both serve the same purpose, they are designed for two completely different types of transportation and I'd be a little bit more leary of trying to do anything to an airplane engine than a car's engine.
Second, science is always changing. For almost two centuries no one dared touch Newton's law of gravity, until Einstein came along with the theory of general relativity, which was then challenged by Bohr's theory of quantum mechanics, which was then challenged by string theory. If science didn't change then we'd still be driving around in Model T's.
11-04-2003, 04:33 AM
#62
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Originally posted by BriGuyMax
Yes they are...BUT you have no PROOF that pullies hurt our motor.
Read frenzee's post...the application you cited was much more stressful to the motor than our application.
Wow...I just realized how old this thread is...
November four seven delta victor.....hot car...like the rims
Sorry if I came off a little harsh the first time...
Yes they are...BUT you have no PROOF that pullies hurt our motor.
Read frenzee's post...the application you cited was much more stressful to the motor than our application.
Wow...I just realized how old this thread is...
November four seven delta victor.....hot car...like the rims
Sorry if I came off a little harsh the first time...
11-04-2003, 05:34 AM
#63
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LOL I have read through all of this and it just makes me feel like I really didn't spend enough time in my science classes LOL... So what's the bottom line here? UR pulleys good or bad?
11-04-2003, 07:21 AM
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I don't know what to believe, but I doubt UR would be in business if their products were known to destroy engines 
. I just said F*** it and ordered the crank pulley Monday. I've been bitten by the speed bug and this seems to be a cool little mod. I ordered the black one to make me feel a little better (it looks more like the stock one so I won't worry about it everytime I open my hood). If the pulleys do start harming engines at least I won't be alone as several Z owners have them as well
. I just said F*** it and ordered the crank pulley Monday. I've been bitten by the speed bug and this seems to be a cool little mod. I ordered the black one to make me feel a little better (it looks more like the stock one so I won't worry about it everytime I open my hood). If the pulleys do start harming engines at least I won't be alone as several Z owners have them as well
Last edited by 350Z_Redline; 11-04-2003 at 08:56 AM.
11-04-2003, 08:46 AM
#65
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The theory proposed above is a good one, and is based in reality. However, there are several flaws to it.
As noted above, most modern cars are balanced internally, no texternally, as they were in days of old. The rubber pieces sometimes found on a modern day crank pulley is not there for balancing the crank at all, it is there to absord the vibration that can occur on some motors due to belts, as well as absorb the noise of that belt. If you had proof of a VQ motor snapping a crank, then I would say you ahve some validity. But giving us an example of an airplane motor (not sure if you specified maker or history of it), is not an accurate comparison in the least.
In short, to say they are universally bad or universally good is not at all accurate - it is strictly on a case by case basis depending upon how the stock pulley was made.
As noted above, most modern cars are balanced internally, no texternally, as they were in days of old. The rubber pieces sometimes found on a modern day crank pulley is not there for balancing the crank at all, it is there to absord the vibration that can occur on some motors due to belts, as well as absorb the noise of that belt. If you had proof of a VQ motor snapping a crank, then I would say you ahve some validity. But giving us an example of an airplane motor (not sure if you specified maker or history of it), is not an accurate comparison in the least.
In short, to say they are universally bad or universally good is not at all accurate - it is strictly on a case by case basis depending upon how the stock pulley was made.
11-04-2003, 10:35 AM
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you guys can keep asking me questions as long as you want.... I've already said I'm done with this thread... I was done with it months ago before it was ressurected.
Some of you make very valid points. There are good points to be made on either side. It's simply an issue of "tastes great... less filling!"
so long.... good day... over and out....
Some of you make very valid points. There are good points to be made on either side. It's simply an issue of "tastes great... less filling!"
so long.... good day... over and out....
11-04-2003, 12:04 PM
#68
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LESS FILLING
Seriously though. Frenzee summed it up best. I followed this issue for a long time and I now say after being skeptical, I will get the pulleys!
Seriously though. Frenzee summed it up best. I followed this issue for a long time and I now say after being skeptical, I will get the pulleys!
11-04-2003, 12:05 PM
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Originally posted by Z1 Performance
The theory proposed above is a good one, and is based in reality. However, there are several flaws to it.
As noted above, most modern cars are balanced internally...
The theory proposed above is a good one, and is based in reality. However, there are several flaws to it.
As noted above, most modern cars are balanced internally...
Balancing an engine is different than dampening the crankshaft (edit).
Even so, you can probably get away with the pulleys on an NA engine for many, many miles before any problems show up.
A good analogy might be that using the one piece pulleys is more like eating 6 fried eggs at Waffle House every day than it's like smoking crack daily. The results are probably the same it's just a matter of how long it takes to get there.
Also, I think bearing failure is more likely than a snapped crankshaft (edit).
If you significantly increase the torque output of the engine (forced induction) or raise the redline considerably (hit another harmonic) then I'd leave the stock pulley and possibly even consider getting a better solution to dampening the harmonics of the crankshaft (edit).
(edit: Accidentally referred to crankshaft as driveshaft. Fixed.)
--
Jeff
Last edited by jeffw; 11-04-2003 at 04:03 PM.
11-04-2003, 04:00 PM
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Originally posted by Z1 Performance
who said anything about snmapping a drivehshaft?
who said anything about snmapping a drivehshaft?
Sorry I meant crank shaft. Some reason I have the habit of mixing the two up.
--
Jeff
11-05-2003, 05:17 AM
#73
I was wondering when this wave was gonna hit here with all the people using these pullies.
On my MR2 and my Civic, both extreme engines, i have solid aluminum crank pullies. i will blow those motors up far before harmonics destroy my crank. You can definatly get away with it for a long time.
i have read about this tons of times and forgot more than i remember, but i remember my decision and how i came to it. now... to be realistic here. this is what it comes down to guys.
Take a look at your stock crank pulley. Is your stock crank pulley seperated into 2 pieces bonded together with a hard rubber therefore acting as a HARMONIC DAMPENER?
If it is....
Would you ever think that its cheaper to do this than it is to just use a solid aluminum one that would even make more HP?
You must trust Nissan, cause you bought their car... so by arguing about if your car should have that dampener on there or not, your argueing with the engineers that designed the engine you just bought.
If Nissan is affraid that harmonics over time will fatigue failure my crankshaft without that dampener... than so am I.
I havent spent millions researching harmonics and their effects on crankshaft durability in piston engines. Have you??
How about someone calls up UR and asks how much research and testing they have done with harmonics on crankshafts? Have they ever R&D'd and provided engines for production vehicles expected to last over 100,000 miles? Not to bash UR... their pulleys are great... if your looking for a solid aluminum crank pulley they are hard to beat. But remember one thing.... Nissan > Unorthodox Racing
You can talk about changing science, etc etc. But do you think that you and UR figured out something before Nissan, and all the other manufacturers? Not likely. Changing science is what brought you these harmonic dampeners. Do you think they didnt do any testing to determine if it was needed for them to use a more complicated dampening pulley on all their engines?
i trust Nissan's judgement. ill keep the stock pulley.
On my MR2 and my Civic, both extreme engines, i have solid aluminum crank pullies. i will blow those motors up far before harmonics destroy my crank. You can definatly get away with it for a long time.
i have read about this tons of times and forgot more than i remember, but i remember my decision and how i came to it. now... to be realistic here. this is what it comes down to guys.
Take a look at your stock crank pulley. Is your stock crank pulley seperated into 2 pieces bonded together with a hard rubber therefore acting as a HARMONIC DAMPENER?
If it is....
Would you ever think that its cheaper to do this than it is to just use a solid aluminum one that would even make more HP?
You must trust Nissan, cause you bought their car... so by arguing about if your car should have that dampener on there or not, your argueing with the engineers that designed the engine you just bought.
If Nissan is affraid that harmonics over time will fatigue failure my crankshaft without that dampener... than so am I.
I havent spent millions researching harmonics and their effects on crankshaft durability in piston engines. Have you??
How about someone calls up UR and asks how much research and testing they have done with harmonics on crankshafts? Have they ever R&D'd and provided engines for production vehicles expected to last over 100,000 miles? Not to bash UR... their pulleys are great... if your looking for a solid aluminum crank pulley they are hard to beat. But remember one thing.... Nissan > Unorthodox Racing
You can talk about changing science, etc etc. But do you think that you and UR figured out something before Nissan, and all the other manufacturers? Not likely. Changing science is what brought you these harmonic dampeners. Do you think they didnt do any testing to determine if it was needed for them to use a more complicated dampening pulley on all their engines?
i trust Nissan's judgement. ill keep the stock pulley.
Last edited by phunk; 11-05-2003 at 05:33 AM.
11-05-2003, 05:36 AM
#74
BTW i definatly dont want to offend anyone... those are just my personal thoughts on why i will not be putting a pulley on my Z which i plan to not blow up for a long long time.
everyone has their own priorities, and has the right to do as they will. I would never think poorly of someone for making a decision that doesnt match mine. I just like to give my feedback on some topics and hope it gives some people a little food for thought to help them make their own decision.
everyone has their own priorities, and has the right to do as they will. I would never think poorly of someone for making a decision that doesnt match mine. I just like to give my feedback on some topics and hope it gives some people a little food for thought to help them make their own decision.
11-05-2003, 06:12 AM
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Too many people here are assuming the intent of the Nissan stock crank pulley design is for crankshaft/journal bearing/or connecting rod preservation. Unless anyone is a Nissan engine engineer, it is pointless for anyone to assume the design intent. The sky is not falling. Nissan built this motor with economic pressures to place this engine in many platforms like mom and pops' sedans and soccer moms' Muranos. It'd be interesting and add validity to the argument that the crank pulley is different on say a 3.5 lower HP 3.5 vs. the 350Z 3.5. Even that may simply be a matter of production economics based on contingent ancillary applications. For example, Nissan engineers could be using a different crank pulley on other 3.5 iterations simply because it matches an overstock of some ex-platforms belt surplus. Too much speculation behind the panic, IMHO. One has to wonder where cost factors and reliability concerns intersect in an approved project design. No one here knows. Edited for spelling review. 
Last edited by Z Monster; 11-05-2003 at 06:14 AM.
11-05-2003, 12:05 PM
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Originally posted by phunk
i dunno... they call it a harmonic dampener for a reason.. what other function would it serve? you have a semi valid point.
i dunno... they call it a harmonic dampener for a reason.. what other function would it serve? you have a semi valid point.
Istook on pullies
11-05-2003, 12:17 PM
#78
thats an interesting read but still an individual's opinion.
i never stressed it very much cause i never really thought too deeply into it... just read different things from people qualified in different ways. my basic asumption i mentioned a few posts up, i told myself that until I had adequate evidence i would only use those pullies on my maximum effort engines that im not affraid to break... and that i would stay stocker on the engines that i wanted to have last a long time and can sacrafice a couple ponies.
other than my asumptions based on the fact that the car came with one... i have no personal opinion on its effectiveness. frankly i dont even really understand how it supposedly dampens those harmonics regardless of how many artistic diagrams i have seen.
if someone could show me evidence that it is just there for the engine to feel smoother, which i doubt is true but is possible, then i would gladly throw mine out the window.
I am in this industry everyday, and i talk to countless other tuners and engine builders all the time. its kinda funny but no one knows PRECISELY if you need that thing or not... everyone is just the kinda guy that uses it, or not uses it.
theres 10 types in people in the world, those that understand binary and those that dont. which has nothing to do with anything... but i read that today and found it funny.
i never stressed it very much cause i never really thought too deeply into it... just read different things from people qualified in different ways. my basic asumption i mentioned a few posts up, i told myself that until I had adequate evidence i would only use those pullies on my maximum effort engines that im not affraid to break... and that i would stay stocker on the engines that i wanted to have last a long time and can sacrafice a couple ponies.
other than my asumptions based on the fact that the car came with one... i have no personal opinion on its effectiveness. frankly i dont even really understand how it supposedly dampens those harmonics regardless of how many artistic diagrams i have seen.
if someone could show me evidence that it is just there for the engine to feel smoother, which i doubt is true but is possible, then i would gladly throw mine out the window.
I am in this industry everyday, and i talk to countless other tuners and engine builders all the time. its kinda funny but no one knows PRECISELY if you need that thing or not... everyone is just the kinda guy that uses it, or not uses it.
theres 10 types in people in the world, those that understand binary and those that dont. which has nothing to do with anything... but i read that today and found it funny.
Last edited by phunk; 11-05-2003 at 03:13 PM.
11-05-2003, 07:34 PM
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I am also tempted to purchase pullies, and have read this with great interest. Here's some more food for thought....
http://www.uniqueautosports.com/pulley_kits%20300ZX.htm
http://www.uniqueautosports.com/pulley_kits%20300ZX.htm
11-06-2003, 12:39 AM
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A very good point right here! Thanks for the link VFR!
So by dramatically reducing the weight and inertia of the crank pulley, the natural frequency of the crankshaft is shifted and its ability to self-excite is greatly reduced. So in fact it is the harmonic balancer's own weight that necessitates the dampening, and since the weight of a GFB crank pulley is typically about 20% of the factory component it cannot supply an exciting force significant enough to damage the crankshaft.
An opinion often expressed is "if the manufacturer put it there, it must be there for a reason". However, if you look at it from the car manufacturer's point of view, casting pulleys from steel is very cheap and easy, because they can be produced in large numbers and there is no waste (as opposed to machining them from billet). But because the resulting pulley weighs significantly more than one made from aluminium alloy, it requires dampening.
An opinion often expressed is "if the manufacturer put it there, it must be there for a reason". However, if you look at it from the car manufacturer's point of view, casting pulleys from steel is very cheap and easy, because they can be produced in large numbers and there is no waste (as opposed to machining them from billet). But because the resulting pulley weighs significantly more than one made from aluminium alloy, it requires dampening.