SizongZ

iTrader: (1)

Why do you think I'm sitting here on the internet trying to figure out how these things work. Pretty much any after market mod can have the tendency to void your warranty or ruin your car it all depends on the application and circumstances....
Like the CAI... ohhh if you get water in there it will jack up your engine..... I've never had any problems with CAI's in any of my cars but I don't go try driving through huge water puddles to see if it will..... and unlike max.. I'm not going to deal with N20 on my Z and that's where he said he's having the problem

but are you going to answer my question about the different kinds of crank pulleys out there. Some with balancer, some with dampeners, and some with none?????

disc108

please list some examples from the telecommunications world where science is not always right. thanks.

N74DV

Not all engines are created equal. Stroke, piston & rod weight, angle of opposition, rpm, etc.. all play important roles in the torsional distortion of the crank.

I can't speak for the reasons one specific engine may have an external damper while others may not. Keep in mind the pulley end is only one side where a damper can be placed. It's likely that an engine with a pulley that has no damper ring may have a tuned flywheel to oppose and absorb torsional distortion.

If you want to assume that just because car "X" has no damper pulley that you should be allowed to run without one then you may be asking for problems.... you have to look deeper than the surface... find out if those non damped pulley engines are using another form of tuned mass damping....

SizongZ

iTrader: (1)

That's my point N74DV how do you know the UR pulleys for the VQ doesn't work.
Max only had problems with it when he ran of N20 which most likely UR didn't really take into account under normal circumstances. Max even stated that they ran great while not running on juice.
Who knows why Nissan put that rubber ring in there. Maybe the UR guy is right and it's used to reduce NVH.
I've always heard good things about UR. Max is the first time I've heard problems running their pulleys but he was running N20 at the time.
And I'm not saying that just because engine X does not have a dampener on it that mine shouldn't either. But you are saying that because the stock one has one and the UR doesn't that it's junk and it will kill the motor.
I'm sure UR didn't just pick up a pulley and say.... oh we'll sell this for the 350z we won't bother testing it. If it works for them I'll try it out. If I have problems then out it comes.... not a biggie.... live and learn process
Most likely the same things that I'm going to go through when I get the time to twin turbo my Z.


And Disc108 just think of all the process that it took to run from normal voice lines to Fiber Optics. Always changing... always getting better.

disc108

But that still doesn't answer my question. What are specific examples in the telecommunications industry that defies the laws of science? Because if this were true, it wouldn't be "science" in the first place.

N74DV

yeah... He sorta stuffed his foot in his mouth when he said science "changes"

Maybe he meant "evolves"... or "progresses"...

Besides... his comment was with regards to harmonics... harmonics is all mathematics.... 3+3 will always be 6 no matter how thin you slice it.

SizongZ

iTrader: (1)

isn't changing the same thing as evolving and progressing. If it evolves it's not the same as it used to be so it changed?


Laws of science??? what exactly is that? Is there a actual law.. where something is either right or wrong?

Definition of science

1a The observation, identification, description, experimental investigation, and theoretical explanation of phenomena.
b Such activities restricted to a class of natural phenomena.
c Such activities applied to an object of inquiry or study.
2 Methodological activity, discipline, or study: I've got packing a suitcase down to a science.
3 An activity that appears to require study and method: the science of purchasing.
4 Knowledge, especially that gained through experience.
Science Christian Science.

science is not a fact... it's only what can be proven. And even after being proven once someone can come and prove you wrong.

Mathematics is still a huge part of science.
and you should try asking a mathematician about your 2+2=4. He'll have a ball with that

Canadian350Z

For the scientists out there...

What does 100+10 equal?

What about 100+10.0?

What about 10.25+13.3?

The true scientists out there will know where I'm going with this....

Any takers?

Cheers!

D'oh

Science is constantly changing. Remember back in the good old days when people thought the ATOM was the smallest particle possible (A-TOM from latin or greek means not-cut). We now know that is not correct.

In science theories are contested and dis-proved frequently, only to be replaced by a new theory that better represents experimental data.

Now, science of vibration has not changed significantly in the past 100 years, so that argument doesn't work too well here.

However, remember that there are two things that contribute to resonant frequencies: inertia and stiffness. The material properties affect both of these factors, but so does the distribution of the material. Cross drilling a pulley will definitely reduce weight and change the natural frequency of the system, but (depending on where the holes are drilled) it can also reduce the natural frequency of the pulley itself, because the pulley is less stiff. This will have an effect on the overall system, but it would probably be marginal.

Now, I never got to see the pictures of the stock crank pulley VS the lighter one, so I will be talking in theory here. If the stock pulley is mounted rigidly to the shaft, then the rubber "damper" won't do anything. However, if the stock pulley is retained to it's own shaft via the flexible rubber, and it's only that shaft that is bolted rigidly to the crank, then there will be a definite difference.

I guess one significant unknown at this time, is how well, if at all, the stock system is tuned. Is the stock pulley mass and the size and shape of the gasket specifically matched to create a specific natural frequency, or is it there simply for NVH as mentioned above? It seems like it should be pretty simple to run an analysis on the stock pulley/gasket combo, and then design a replacement with a reduced mass and also a gasket with reduced stiffness so the resonant frequency will match that of the stock system's.

I have access to an FEA program but am pretty bad about doing any extra work. Im still trying to finish my license plate bracket that I started 6 months ago. Might be interesting to take a look at this, though.

-D'oh!

N74DV

inertia has nothing to do with an objects resonant frequency... maybe you mean mass and stiffnes (elsaticity)?

The stock pulley a two piece design and has a damper ring between the two pieces. The inner piece is directly mounted to the crank. The outer drives the power steering pump.

the UR "explanation" is bogus... if it was for NVH then how in the hell does the inner pulley, which is connected directly to the crank with no damper, filter out any vibes to the other accessories?

NVH is handled alot with the belts themself.... UR is protecting thier a$$. If the truth were revealed they'd lose 50% of their business in a flash.

All some of you folks need to do is a little research....

SizongZ

iTrader: (1)

Isn't that what we are trying to do hear. But it seems to me anything that is said that conflicts to what you believe is wrong?
Don't forget science is about theoretical observation. First you tell me I'm wrong about the drilled holes on the pulley and then you say I'm somewhat right.

All I'm saying is explore the possiblities. I'm been trying to get some type of documents on how the crank shaft is built and how the stock pulley works. So far it seems to me that we are trying to figure how the crank works and the pulley without really knowing how it was designed. Like you said.... just because motor "X" looks similar to motor "Y" doesn't necessarily mean it works the same.

I have a book from japan that pretty much goes through the in's and out's of the new Z but it's entirely in japanese and I can't read 95% of the Kanji. Have to wait for a friend to come by to look at it and start translating.

And I think inertia does have something to do with resonant frequency. Take a bicycle wheel and spin it. The faster it goes it will vibrate more and make more noise as it spins.

N74DV

WTF?

What you are experiencing here is amplitude. Sure the faster you spin it (more inertia) the "louder" it gets... thats the amplitude of the sine wave...

stay on topic... we're talking frequency here... inertia is not a factor in determining resonant frequency.

If youre into telecommunications I'd have thought you understand the fundamentals of sine waves.

jeffw

Out of curiosity, what did the harmonic balancer look like on your airplane engine (the one you removed)?

Was it an off balance counterweight type flywheel or was it a balanced fly wheel with an energy absorbing medium such as rubber?

--
Jeff

N74DV

It was a two piece design with an inner portion connected directly to the crank and an outer mass ring. They were bonded with a rubber ring.

D'oh

Umm...sorry I meant "moment of inertia" (which is actually what governs the vibration, not mass), but it's basically the same thing. In either case, my explanation still holds.

And just to clarify, I am talking about the natural frequency of a spring mass system, where the spring would be the crank and the mass would be the pulley. Since we are talking about the rotational natural frequency, we definitely need to consider the rotational inertia of the pulley, since that is what would be considered as the mass.

Now, switching back to a more linear type example, we an see that the inertia is again a critical factor.
Let's use your ruler example again.

You take your pebble and move it closer to the fixed end of the ruler, and the resonant frequency will increase, even though the mass of the system and the stiffness of the ruler are still the same.

Back to our rotational example:
By the same token, I can use a cross drilled pulley with the material concentrated near the outer edge and it will have a different moment of inertia than a pulley of the same mass but with the material concentrated closer to the center. When you couple these pullies to a spring (like the crankshaft) the natural frequency of the two systems will be different, even though the mass is the same. It is actually the inertia of the system with respect to your constrained points that is the critical factor.

If you do not understand this, then I guess there is at least one more of us who needs to do a little research.

I do appreciate your explanation of the pulley though, as it does indicate that it could potentially have been tuned from the factory to counteract vibration in the crankshaft. The NVH argument still holds some water, because the rubber damper between the two pulley portions would help filter out some of the power steering vibrations, but overall it does seem like a pretty weak argument, since as you mentioned, the other accessories are coupled to the rigidly mounted pulley.

I meant no offense with the above, but it did seem like you were quick to make some snide remarks about the rest of us and so I had to come out to defend my honor. (Like when Homer decided to duel everyone in town - "I demand stisfaction"... )

Peace,
D'oh!

SizongZ

iTrader: (1)

So you are saying there is no resonant frequency in a spinning wheel????

From what I remember for something to create resonant frequency it needs to be excited for instance a tuning fork. But since we are talking about a pulley it needs to spin. Well to get it to spin it needs some type of force to get it to move, like torque, since we are again talking about pulleys. If you look at Newtons 2nd law of rotation it takes angular acceleration and moment of inertia to create some type of torque.
Point being that the pulley is not going to make any type of resonant frequency when not in motion and it's going to take some type of inertia to get it to move..... thus creating some resonant frequency.

And isn't sound also part of resonant frequency. Like the tuning fork I mentioned? Tuning fork vibrates enough to create a specific sound?

And I didn't just say that it only make more noise.... it also vibrates more and you kinda left out the vibrating part.

N74DV

no snide remarks intended to anyone but one member who knows who he is... his assumptions and remarks were unfounded speculative.

D'oh, your remarks make sense and fall within the range of discussion. I had not factored in moment of inertia in determining a systems resonant frequency.

Still.... considering this, I find it unlikely that the reasons UR pulleys have the holes in the locations they do is due to data received under extensive testing to determine the optimal damping frequncy for the pulley.... sorry, but I don't buy it..

what I do buy is UR put some pretty holes in a finely turned hunk of 2024 aluminum and call it a lightened/underdrive pulley.... they do that with no regard to the actual use and operation of the stock pulley.

that's my issue.

N74DV

I'm not trying to be mean... but maybe you ought to hold off on the posts until you can actually bring something to the table that makes sense... What exactly was your last argument supposed to do?? I'm lost?

SizongZ

iTrader: (1)

ok... now I'm confused with your two posts.... hahahaha

but anyways about your remark about UR pulleys.. like I mentioned before I've always heard good things about UR's pulleys. Never had I heard anything wrong with them until max posted his dilemma with them. And even now max is running test to see if it is the pulley. He just found that he found problems with his N20 setup which actually maybe the problem. If he still has problems with the pulleys after he fixes his N20 problem then I will go get my mechanical engineer friends and look into it more myself.

joust75

iTrader: (1)

I am skeptical that the lack of this tiny rubber ring on the pulley can make or break a motor. If it unbalanced the crank I think performance would suffer. Instead dynos show power increases all across the power band!
Butt dynos show significant power increases as well.

All the same, this talk has got me worried. I am holding off a UR purchase till I know more!