UR Pulleys & Harmonic Balancers - in general
11-16-2003, 09:47 AM
#101
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I waited a while for someone else to do it, but I guess I am going to have to add the last post to bring this thread up to an even 100.
It has all been very interesting and informative. UR pulleys were the only performance upgrade I was seriously considering. All of the comments back and forth have caused me to rethink, which is exactly what these forums are supposed to do, imho.
Thanks to N74DV and all the others for the excellent description of harmonic balancers et al; I never would have considered all that. I am sure it has some effect, but I think that in the case of the airplane, having a big old propeller yanking several thousand pounds of airplane through the air may have something to do with why the crank snapped, multiplying the effects of harmonic resonance.
In the Z though, I think there is probably not enough difference between the weight and construction of the UR pulley and stock pulley to make a significant difference over the life of the engine, as far as the effects of harmonic resonance go. I would feel safe enough replacing the stock with the UR pulley.
That said, I will probably not be switching the stock pulley. The difference between the two is only about 5 – 8 hp, according to everything I’ve read. I doubt I would be able to tell the difference, seat-of-the-pants wise. If there are any mathematicians on board maybe they could do a statistical analysis and determine a p value to tell if there is a significant difference between what? 250 and 257?
Lastly, the topic of science. It isn’t really a force or an authority in the way that the government or church are authorities. For a while we did not understand how bumblebees flew, although we were pretty sure we understood birds and airplanes. Bumblebees were not “unscientific”, our understanding of the aerodynamics of bees was faulty.
Science does not deal in facts, at least not in the way that may people think of facts, as absolutely immutable unchangeable statements of the way things are. Science deals in probabilities. Probabilities that certain theories are correct. Someone mentioned Newton’s theory of gravity, which was believed to be correct for several hundreds of years. Most observations we could make and experiments we could do supported the theory.
But there were a few logical anomalies that bothered Einstein. Chiefly, Newton’s theory implied that gravity’s effects would be felt instantaneously throughout the universe, which violated the condition that nothing can travel faster than light. Einstein’s theories completely changed the way we think about gravity, and space and time, but we still use Newton’s equations because they work so well in everyday situations.
The equations were not wrong. Probably it would be more accurate to say that the theory behind the equations was incomplete. It lacked a description of what the force of gravity was and how it worked. The description is still incomplete, but we do have a better understanding, and for most of us here there is a pretty good chance that the phenomena of gravity will be understood within our lifetimes. Kind of exciting when you think about it.
So science is this then: the quest for understanding. Our experience has been that understanding is best achieved through observation >> theory >> experimentation >> observation >> theory >> experimentation >> and so on and so on until we have groups of interlocking theories which support one another and explain more and more of what we can experience.
Of course it may all come crashing down one day when it is discovered that the laws of nature are governed by the application of pixie dust, but the more we learn, the less likely that seems.
There are four ways we can know something: Through tradition, because everyone before us has believed it. Through authority, because those in power say it is so. Through reason, because we have thought about it and it seems logical to us, and through experimentation, because we have made our own observations and tested our own theories.
The last method is the most reliable, but because of obvious limitations we have to make do with supplementing from the other three.
pArtY on DUDE!!!
It has all been very interesting and informative. UR pulleys were the only performance upgrade I was seriously considering. All of the comments back and forth have caused me to rethink, which is exactly what these forums are supposed to do, imho.
Thanks to N74DV and all the others for the excellent description of harmonic balancers et al; I never would have considered all that. I am sure it has some effect, but I think that in the case of the airplane, having a big old propeller yanking several thousand pounds of airplane through the air may have something to do with why the crank snapped, multiplying the effects of harmonic resonance.
In the Z though, I think there is probably not enough difference between the weight and construction of the UR pulley and stock pulley to make a significant difference over the life of the engine, as far as the effects of harmonic resonance go. I would feel safe enough replacing the stock with the UR pulley.
That said, I will probably not be switching the stock pulley. The difference between the two is only about 5 – 8 hp, according to everything I’ve read. I doubt I would be able to tell the difference, seat-of-the-pants wise. If there are any mathematicians on board maybe they could do a statistical analysis and determine a p value to tell if there is a significant difference between what? 250 and 257?
Lastly, the topic of science. It isn’t really a force or an authority in the way that the government or church are authorities. For a while we did not understand how bumblebees flew, although we were pretty sure we understood birds and airplanes. Bumblebees were not “unscientific”, our understanding of the aerodynamics of bees was faulty.
Science does not deal in facts, at least not in the way that may people think of facts, as absolutely immutable unchangeable statements of the way things are. Science deals in probabilities. Probabilities that certain theories are correct. Someone mentioned Newton’s theory of gravity, which was believed to be correct for several hundreds of years. Most observations we could make and experiments we could do supported the theory.
But there were a few logical anomalies that bothered Einstein. Chiefly, Newton’s theory implied that gravity’s effects would be felt instantaneously throughout the universe, which violated the condition that nothing can travel faster than light. Einstein’s theories completely changed the way we think about gravity, and space and time, but we still use Newton’s equations because they work so well in everyday situations.
The equations were not wrong. Probably it would be more accurate to say that the theory behind the equations was incomplete. It lacked a description of what the force of gravity was and how it worked. The description is still incomplete, but we do have a better understanding, and for most of us here there is a pretty good chance that the phenomena of gravity will be understood within our lifetimes. Kind of exciting when you think about it.
So science is this then: the quest for understanding. Our experience has been that understanding is best achieved through observation >> theory >> experimentation >> observation >> theory >> experimentation >> and so on and so on until we have groups of interlocking theories which support one another and explain more and more of what we can experience.
Of course it may all come crashing down one day when it is discovered that the laws of nature are governed by the application of pixie dust, but the more we learn, the less likely that seems.
There are four ways we can know something: Through tradition, because everyone before us has believed it. Through authority, because those in power say it is so. Through reason, because we have thought about it and it seems logical to us, and through experimentation, because we have made our own observations and tested our own theories.
The last method is the most reliable, but because of obvious limitations we have to make do with supplementing from the other three.
pArtY on DUDE!!!
01-24-2004, 08:03 PM
#102
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From the UR site:
4) "Is my crank pulley a harmonic/torsional/vibration damper or a harmonic balancer?"
People are getting the pulleys confused with the harmonic dampers found on some V6 / V8 engines. "Harmonic Balancer" is a term that is used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper, hence the merging of the two terms. None of the applications that we offer utilize a counterweight as part of the pulley as these engines are internally balanced.
The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley that looks similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress natural vibration and noise from the engine itself, the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to note that in these applications, this elastomer is somewhat inadequate in size, as well as life span, to act as an effective torsional damper. If you look at the pulleys on some of the imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda, the Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's, to mention a few. This is not to say that with our pulleys you will hear a ton of noise or feel more vibration from your engine compartment. Most who have installed and driven a vehicle with our pulleys will notice the engine actually feels smoother. This is a natural result of replacing the heavy steel crank pulley with a CNC-machined aluminum pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.
The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as stroke, displacement, inline, V configurations, power output, etc., do determine when and how these harmonics and torsional movements occur.
Again, there is a lot of internet hearsay about the pulleys. When motor failures occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem. We hope that after reading this you will understand the crank pulleys better.
4) "Is my crank pulley a harmonic/torsional/vibration damper or a harmonic balancer?"
People are getting the pulleys confused with the harmonic dampers found on some V6 / V8 engines. "Harmonic Balancer" is a term that is used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper, hence the merging of the two terms. None of the applications that we offer utilize a counterweight as part of the pulley as these engines are internally balanced.
The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley that looks similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress natural vibration and noise from the engine itself, the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to note that in these applications, this elastomer is somewhat inadequate in size, as well as life span, to act as an effective torsional damper. If you look at the pulleys on some of the imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda, the Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's, to mention a few. This is not to say that with our pulleys you will hear a ton of noise or feel more vibration from your engine compartment. Most who have installed and driven a vehicle with our pulleys will notice the engine actually feels smoother. This is a natural result of replacing the heavy steel crank pulley with a CNC-machined aluminum pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.
The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as stroke, displacement, inline, V configurations, power output, etc., do determine when and how these harmonics and torsional movements occur.
Again, there is a lot of internet hearsay about the pulleys. When motor failures occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem. We hope that after reading this you will understand the crank pulleys better.
03-13-2004, 09:46 PM
#103
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Sorry to bring this matter again.
I was wandering if the UR Pulley is installed as well as the Lighter Flywheel. Wouldn't it will balance it? And this Harmonic balance won't be any problem anymore?
I was wandering if the UR Pulley is installed as well as the Lighter Flywheel. Wouldn't it will balance it? And this Harmonic balance won't be any problem anymore?
03-14-2004, 06:10 AM
#104
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Once again, the pulley on a 350Z has nothing to to with the balance of the crank - these engines are balanced internally.
The only thng the stock pulley has is a small isolator in it, whcih is there to simply absorb belt noise, that is it. It is not a balanced for the pulley at all, as you find on many V8 engines.
What I find amusing is that tons of people do a flywheel without even thinking twice, yet somehow think a crank pulley will be the part to somehow cause damage?
The combo if a flywheel and pulley do not szero themselves out balance wise unless you have an engien builder balance your entire rotating assembly at once (involves disassembling engine). Barring that though, to date ahve not seena single VQ series engine, froma VQ30 on uo, ever fail due to the install of a pulley, or a flywheel.
The only thng the stock pulley has is a small isolator in it, whcih is there to simply absorb belt noise, that is it. It is not a balanced for the pulley at all, as you find on many V8 engines.
What I find amusing is that tons of people do a flywheel without even thinking twice, yet somehow think a crank pulley will be the part to somehow cause damage?
The combo if a flywheel and pulley do not szero themselves out balance wise unless you have an engien builder balance your entire rotating assembly at once (involves disassembling engine). Barring that though, to date ahve not seena single VQ series engine, froma VQ30 on uo, ever fail due to the install of a pulley, or a flywheel.
03-17-2004, 10:44 PM
#106
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Originally posted by isalvus
i was wondering what size is the bolt holding the oem crank pulley, i ordered my ur pulley and was curious thanks
i was wondering what size is the bolt holding the oem crank pulley, i ordered my ur pulley and was curious thanks
03-18-2004, 04:50 PM
#108
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I did a UR pulley on my 3.5l maxima. The car ran faster and stronger. FANTASTIC MOD. Don't listen to this garbage.
If I remember correctly, there is no dampening ring on the pulley. The 3.0l engines had this ring and it needed to be switched over for harmonics. The 3.5l is different, it's built into the pulley and UR takes this into account on how the pulley is made.
Yes, the weight is different, that's the point...the harmonics are probably different as well, but we're not tapping the metal here like a tuning fork, we're in rotation. As long as it's balanced inside, whatever you do outside is not going to make a difference.
Many cars are underdriven with no ill effects whatsoever.
You say we may be slowly destroying our engines, well, how slow? The thing isn't going to last forever anyhow, and I'd like to see how you're math and science can equate to what extent UR pulleys are limiting the life of the 3.5l. Perhaps there are other more important things to worry about, like oil changes!
You do more damage driving in the city than on the freeway, but somehow we still drive in the city, don't we? Please, lets worry about more important things!
If I remember correctly, there is no dampening ring on the pulley. The 3.0l engines had this ring and it needed to be switched over for harmonics. The 3.5l is different, it's built into the pulley and UR takes this into account on how the pulley is made.
Yes, the weight is different, that's the point...the harmonics are probably different as well, but we're not tapping the metal here like a tuning fork, we're in rotation. As long as it's balanced inside, whatever you do outside is not going to make a difference.
Many cars are underdriven with no ill effects whatsoever.
You say we may be slowly destroying our engines, well, how slow? The thing isn't going to last forever anyhow, and I'd like to see how you're math and science can equate to what extent UR pulleys are limiting the life of the 3.5l. Perhaps there are other more important things to worry about, like oil changes!
You do more damage driving in the city than on the freeway, but somehow we still drive in the city, don't we? Please, lets worry about more important things!
05-04-2004, 05:58 AM
#109
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Can someone explain how the stock pulley is supposed to act as a damper at all if the rubber doesn't even go all the way through the pulley? I examined it closely and noticed the rubber is only on one side the other side is metal from the hub out.
05-04-2004, 07:10 AM
#110
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I think we should all step back, rethink this thing, and read the thread below:
https://my350z.com/forum/showthread....threadid=73307
Lou
https://my350z.com/forum/showthread....threadid=73307
Lou
05-12-2004, 01:20 PM
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If you are confident that the pully won't hurt your car, then keep it on or buy it and put it on. Me, no, I don't want to dish out the dough for a jacked up engine so I am going to wait for at least 6 months to see if the pully does pose any problems. That should be the concluded discussion. Science in this since is probably correct, but not one of us designed the motor that is in our car, and 99.9999999% don't know more than 5% of what exactly it does or how exactly it works, so the only way to know if this pully is dangerous is by using it. Good luck to all, but I'm going to stay away for now.
05-12-2004, 01:53 PM
#112
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FWIW I've seen numerous failures on UR pulley equipped cars (not Zeds, but highly modded 4 cyl). The part that failed on those cars (not the crank) I've never seen fail on a car without a pulley mod (and I'm talking about a car I have almost 10 years experience with). I don't know if the Zeds engine will react the same way but I'll never use a pulley mod on any of my cars. For the small gain the risk isn't worth it to me. That's all I'm going to say on the matter.
05-12-2004, 06:52 PM
#115
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ok - the prove me wrong.....I think the deck is stacked clearly in favor of the pullies not harming the stock engines in any way, shape or form.
the post you mentioned above is 100% anecdotal, by a 3rd party, and the "testing" measures they used would not reveal the cause of the problem at all.....only way to do that is an engine teardown. I asked a few very pointed quesions in the thread....funny how we never got an answer to those.
Anyway, if you don't want the pulley, don't get the pulley, it's pretty simple. There are literally thousands of VQ engines that have this pulley and have not had an issue. Let's not forget that sometimes, bone stock engines have issues from the get go. I know of 1 350Z, bone stock, whose engine literally lasted 2800 miles before throwing a rod. I would hardly say that this shows the 350Z to have a weak engine....
the post you mentioned above is 100% anecdotal, by a 3rd party, and the "testing" measures they used would not reveal the cause of the problem at all.....only way to do that is an engine teardown. I asked a few very pointed quesions in the thread....funny how we never got an answer to those.
Anyway, if you don't want the pulley, don't get the pulley, it's pretty simple. There are literally thousands of VQ engines that have this pulley and have not had an issue. Let's not forget that sometimes, bone stock engines have issues from the get go. I know of 1 350Z, bone stock, whose engine literally lasted 2800 miles before throwing a rod. I would hardly say that this shows the 350Z to have a weak engine....
05-12-2004, 07:19 PM
#116
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Z1, Exactly. The whole point of this thread, and the other one, is for people to drink in the data and form their own decision. I did! You did! Our decisions weren't the same, but, I believe, we both interpreted the data in our own way.
I don't want to prove you wrong. I never said you were wrong. I said I disagree with you, and I do.
To me, the data presented, though anecdotal, is enough for me not to want to take the chance on the pulley.
Lou
I don't want to prove you wrong. I never said you were wrong. I said I disagree with you, and I do.
To me, the data presented, though anecdotal, is enough for me not to want to take the chance on the pulley.
Lou
05-13-2004, 08:44 AM
#117
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To me, the data presented, though anecdotal, is enough for me not to want to take the chance on the pulley.
Lou [/B]
Lou [/B]
(g-rated)Can't blame ya tho, engines don't come cheap.
What's upsetting to me is how "scare tactics" are used...I mean, even the title "2 documented engine failures..." ...when in the end, there was really no documentation at all. So sad.
Then you have one guys theory and then another guys theory, and then someone else saying one thing....ugh...so much misinformation...
But again, any mod is a risk....I was even scared after reading these two threads (and I've used underdrive pulleys on 4 different cars with no problems whatsoever.) I just hope people don't start something like this on another mod, because frankly, where does it all end?
05-13-2004, 12:00 PM
#118
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I was scared by all this info at first, everyones posts really cleared things up for me. I will buy the pulleys.
I have seen the stock pulley and it is a pretty crude piece. The rubber isolator setup looks worthless and I doubt that the thing is perfectly balanced. Consider that rubber piece, and the fact that it will dry out and crack over the years. That alone will upset the pulleys balance, if it really is such a precision part.
URs pully is lightweight and precision machined. From seeing the parts and hearing facts. My brain concludes that the pulleys might not only be safe but mayby even better for the car all around.
Those failures mentioned could have been due to faulty bearings, or improper lubrication. I very seriously doubt that a lightened crank wheel could cause a catastrophic engine failure at 30,000 miles!
There is my reasoning. I WILL be enjoying the freed up ponies that the UR will get me.
(If someone from UR is reading this, you can send me a free crank pulley, for my post here!!!)
I have seen the stock pulley and it is a pretty crude piece. The rubber isolator setup looks worthless and I doubt that the thing is perfectly balanced. Consider that rubber piece, and the fact that it will dry out and crack over the years. That alone will upset the pulleys balance, if it really is such a precision part.
URs pully is lightweight and precision machined. From seeing the parts and hearing facts. My brain concludes that the pulleys might not only be safe but mayby even better for the car all around.
Those failures mentioned could have been due to faulty bearings, or improper lubrication. I very seriously doubt that a lightened crank wheel could cause a catastrophic engine failure at 30,000 miles!
There is my reasoning. I WILL be enjoying the freed up ponies that the UR will get me.
(If someone from UR is reading this, you can send me a free crank pulley, for my post here!!!)
05-17-2004, 09:01 AM
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what about a flywheel that is 8 pound and has a low moment of inertia? SPecifically the tilton piece, will this modification place any load on the crankshaft bearings?
05-17-2004, 09:07 AM
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Originally posted by adanande
what about a flywheel that is 8 pound and has a low moment of inertia? SPecifically the tilton piece, will this modification place any load on the crankshaft bearings?
what about a flywheel that is 8 pound and has a low moment of inertia? SPecifically the tilton piece, will this modification place any load on the crankshaft bearings?