Nissan 370Z Forum - the crank shaft its harmonic balance?

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the crank shaft its harmonic balance?

Im thinking in get the pulley for the Z...but I want to know if Its the crank shaft harmonic balance????

Please use the search feature

50% think it's internally balanced, 50% think that if you replace the OEM crank pulley you'll fúck something up...

Personally, I know Mike at NST personally, lol

And I run the 20% under drive pulley without an alternator pulley with no issues, I think it's an amazing mod

It's strange that we can't get a straight answer on this. Wouldn't one of the shops on the forum know definitively exactly how it's balanced? Particularly the one that sells the pulleys?

Quote:

Originally Posted by dP3NGU1N (Post 2119530)

It's strange that we can't get a straight answer on this. Wouldn't one of the shops on the forum know definitively exactly how it's balanced? Particularly the one that sells the pulleys?

The guys selling pulleys sell THOUSDANDS and ALL say the engines are internally balanced... IIRC Mike@NST says that the Harmonics thing is BS, that it would make a difference if our cars were F1 cars spinning at 18k RPM, not 8K
And Mike is a smart guy

It's like wheel spacers, fúck ups come from bad installs... My pulley has been on for... 8k miles, just checked it whole it was on the lift, no issues I can see!

dont know why u would risk damaging your engine by throwing off its harmonics to pick up 3 hp...

Its a harmonic DAMPER, it does not balance the engine. Yes it is damaging to remove it. That's why almost every single car has one.

Is there a harmonic damper on the engine?

I searched the FSM for "harmonic", "balance", and "damp" with no harmonic damper found. Scanning through the pics in the engine sections, all I could find is a crank pulley.

Looking at my engine, the crank pulley doesn't look like it's attached to a damper, but it's difficult to see without pulling the fans (and maybe the radiator) plus I wouldn't be surprised if a modern damper doesn't look like what I'm used to seeing.

I wonder what nissan would haw to say about this. Maybe they'll have the real answer?

The crank pulley is a harmonic damper it has a vibration absorbing material ring in it.

Quote:

Originally Posted by 7419sundat (Post 2119890)

The crank pulley is a harmonic damper it has a vibration absorbing material ring in it.

Thanks.

I had an NST Pulley set installed @ 8k, I'm almost to 43k right now, zero problems. :tup:

Quote:

Originally Posted by DEpointfive0 (Post 2119535)

^^ THIS. I did a lot of research outside of this forum prior to installing mine and came up with the exact same info that Mike at NST posted on his pulley review thread. Go read that thread, it's extremely logical and informative. I've had my pulley on for ~7000-8000 miles with no problems. It's a cheap mod, it gives you more than 3hp, it helps smooth out your acceleration and makes your motor more responsive.

Sent from my iPizzle using magic and new-fangled science stuff

Quote:

Originally Posted by Huck (Post 2119900)

^^ THIS. I did a lot of research outside of this forum prior to installing mine and came up with the exact same info that Mike at NST posted on his pulley review thread. Go read that thread, it's extremely logical and informative. I've had my pulley on for ~7000-8000 miles with no problems. It's a cheap mod, it gives you more than 3hp, it helps smooth out your acceleration and makes your motor more responsive.

This is why I installed it, a minute HP gain is just a plus.

Thanks for your answers! Its becajse I have pucharsed the stillen pulley (80% more lightweight than OEM ) and I just want to be sure that its safe before install it.....or sell it

Compare it to an air filter. Yeah you can run your engine without one and get a little more power and better response but your engine won't last as long...

Quote:

Originally Posted by 7419sundat (Post 2120007)

Compare it to an air filter. Yeah you can run your engine without one and get a little more power and better response but your engine won't last as long...

I think your point doesn't hold it's weight, but...
Whatever you say brother, no one is forcing you to install one.

I have yet to see anyone scientifically and empirically show that with an aftermarket pulley your engine won't last as long.

I've done a little research on this site and a few others in the last few minutes and have come to the conclusion, that, on most modern 4- and 6-cylinder engines, the harmonic damper is just not as important as it was on older engines (especially older V8s).
I would put using a non-damped crank pulley in the same class as using the 7AT for minor deceleration - it's not the best thing to do as far as longevity goes, but it's not all that bad, either. For a lot of ppl the small loss in longevity is more than made up for by the gain in fun.
For a DD that seldom gets near the redline, I'd be comfortable running without a damper. For an engine that will see a lot of high RPM use, I'd want some kind of damper on there.
YMMV.

That damper piece people think dampens vibration is a rubber gasket...that's it. It's made out of iron and heavy, not to magically remove non-existent super dangerous vibrations that emanate from our engine. It's the same reason they made the fluwheel a dual mass, to smooth things out, but it also saps engine response (and power). There aren't a lot of newer vehicles or engine designs that require an external damping mechanism. It's just a pulley. Even the stock piece is called a crank pulley. But alas, I'm wasting my breath to half the forum :)

It is such a polarizing issue, I have a set of NST pulleys and I'm still trying to decide whether I should install them. I did see pics of one forum member who had his NST pulley shatter (wish I could remember who), it's what made me not rush into installing mine.

Probably just gonna talk to the mechanic about it.

Quote:

Originally Posted by lemon-fresh (Post 2120148)

It is such a polarizing issue, I have a set of NST pulleys and I'm still trying to decide I want to install them. I did see pics of one forum member who had his NST pulley shatter (wish I could remember who), it's what made me not rush into installing mine.

Probably just gonna talk to the mechanic about it.

As mentioned before, the stigma of pulleys comes from improper installs, not defective parts. Just like with spacers or extended studs or anything else...

I've had my pulleys on for almost 40k, no problems, hell not even any excess oil burn. :tup:

Anyone here with the stillen pulley installed?

ya i got a stillen crank pulley,its been on for 2 summers,so far no problems,still only making a little over 300whp but am interested to see when i go forced induction if any changes occur cuz of it,at stock power pulley works great

Quote:

Originally Posted by SS_Firehawk (Post 2120144)

So are you leaving yours on after you shell out all that money for your twin SC kit? What do the guys at Gtm recommend?

Quote:

Originally Posted by lemon-fresh (Post 2120148)

I know the member personally who had the shattered crank, hell, I uploaded the pics, LOL
It was shitty install/crankshaft was bad

After the OEM pulley was put back on, it wobbled and even the cast iron one shattered

Oh, if you don't install them, I'll lowball you for your kit, lol

Quote:

Originally Posted by vitinvictor1 (Post 2120192)

Anyone here with the stillen pulley installed?

I do, it's great

Quote:

Originally Posted by 7419sundat (Post 2120263)

So are you leaving yours on after you shell out all that money for your twin SC kit? What do the guys at Gtm recommend?

No, it needs to be removed because it will underdrive the superchargers. I'm sure it can be compensated for using smaller pulley's, but then it starts adding guesswork and would not be representative of the kit's performance. I am debating whether I want to move to a billet aluminum stock sized crank pulley. It's heavier duty than the NST's and Stillen unit, most likely because it's marketed for being usable on supercharged cars as well. I would be hesitant to use my NST pulley with two superchargers tugging at it.

Quote:

Originally Posted by DEpointfive0 (Post 2120359)

I know the member personally who had the shattered crank, hell, I uploaded the pics, LOL
It was shitty install/crankshaft was bad

After the OEM pulley was put back on, it wobbled and even the cast iron one shattered

Oh, if you don't install them, I'll lowball you for your kit, lol

I do, it's great

Will definitely keep that in mind.

This is always a fun discussion here. There's plenty of other threads covering the topic, unfortunately they're all mostly full of folks without the requisite background parroting things they've heard, either from friends or vendors.

Quote:

Originally Posted by DEpointfive0 (Post 2120013)

And you likely never will--it's not worth someone's time to prove they aren't worth it.

For me, I'd feel a lot more comfortable if the vendors published a harmonic analysis to demonstrate that their replacement was kosher.

Quote:

Originally Posted by SS_Firehawk (Post 2120144)

The stock pulley changes the resonance frequency of the assembly, which means it is, by definition, a harmonic absorber(damper). The important question is not what it is, but whether it matters.

wstar had some good commentary on this last time, so I won't waste my breath. you'll notice the discussion in the below post explaining that we are not discussing balancing through the use of an asymmetric pulley, but rather the manipulation of the crankshaft resonance frequency.

Quote:

Originally Posted by wstar (Post 1341417)

Well, there's a lot of confusion on this issue about vibrations, dampening, and external vs internal balancing. I can't settle the matter for our engine, but I can clear a few things up to put the debate more on-point: Yes, our engine is "internally balanced", and that has virtually nothing to do with the debate about the pulleys.

An externally balanced engine means there's actually an asymmetrical counterweight system on the pulley, which balances against the otherwise-imbalanced crankshaft. You will definitely destroy an engine if you were to slap a random symmetrical pulley onto such an engine. Because our engine is internally balanced, there's no specific need for a balancing component on the pulley. The pulley itself is expected to have neutral balance (even weight distribution).

Even with an internally-balanced design like ours, the stock pulley includes a (neutrally-balanced) dampening ring to reduce vibrations. The debate is about whether replacing the stock pulley (poorly machined, crappy metal, with a dampener) with an aftermarket one (much lighter, machined to better tolerances, no dampener) is going to cause long term damage due to increased vibration.

On the "stock" side of the debate is the idea that the stock dampener serves to quiet important harmonic vibrations at specific RPMs, and that without it the engine will slowly tear itself apart (slowly wear out crankshaft bearings at the very least). On the "aftermarket" side of the debate is the idea that the (a) whatever vibrations the stock pulley dampens are relatively trivial and mostly about reducing engine noise heard by the user, and won't cause engine damage, and (b) the more-precisely machined aftermarket pulley is better-balanced to begin with.

There's little doubt that as you push an engine further beyond its design boundaries, you need to be more precise about balance and vibrational issues in general. The tricky question is whether our engine in basically-stock form needs that NVH ring for long-term health or not.

I don't have the time/data/desire to crunch the numbers myself to determine how much it matters to replace the pulley with something else, nor do I have a vested interest in figuring it out. The fact that several folks have put a good number of miles down with these pulleys indicates that the pulleys probably don't change anything terribly dangerous. I do know that if I was to spend my hard-earned dollars on a part, I'd prefer to see a resonance analysis done by the manufacturer before I slapped it on my $30K+ car.

the only problems you are going to have are if it is installed incorrectly. Removing a little rubber ring is not going to damage/destroy your engine, that's just stupid.

Those links are detailing the replacement a traditional rubber dampener or viscous. What needs to be proven is if our stock crank pulley dampens anything having to do with dangerous frequencies. I find little merit in the rubber gasket quelling any vibration at all, it's too small. The only difference I see is one is iron, the others are billet (some may be cast) aluminum.

There is already a thread on this whole topic, this should just be merged with that one. Waste of forum space IMO, there are no revelations here. Even the links are the same.

School yourself guys.. For those of u thinking external harmonic balancers reducing crank deflection is a myth, go do some researching on other forums. It won't take long to find case after case of lw pullies causing premature engine failure. In addition, what happens when u mate 2 different metals with 2 differente melting/annealing points... They will fuse. Again, look around and its not hard to find cases of this happening. Why anyone would put something so potentially catastrophic on an engine to gain 3hp is beyond me

Quote:

Originally Posted by edub370 (Post 2121308)

Naaaaa! Just take it off and detonate that engine!

Quote:

Originally Posted by SS_Firehawk (Post 2121299)

Are you kidding?? The first article specifically talks about how solid crank pulleys are bad. The second article covers every single detail in harmonics and even shows how you test for it. TORSIOGRAPH
Maybe you need to actually read them, or find better data than that proving it wrong...

Quote:

Originally Posted by 7419sundat (Post 2121555)

Maybe you should have read the original thread, and if we have a harmonic balancer, damper, dampened pulley, whatever name you want to give it, wouldn't you see one on the car? Look at the crank pulley, remove the damn thing and look at it, there is nothing about it that dampens harmonics. It keeps the motor from dropping revs too fast, just like the stock flywheel in an attempt to keep drivability in tact.

Data is in the numbers. Name or show one, just a single VQ37VHR motor that had catastrophic failure that was absolutely, without a fraction of a doubt caused by an aftermarket crank pulley that was installed correctly. Do you really think I would come into a debate and not do my homework on why you argue against light weight pulleys? Only a fool debates without research. Show me concrete evidence. BTW, I've read both links before you posted them a while ago. There is no talk of an undampened crank pulley with the exception of low RPM V8's.

I reckon your the one that needs to do some more reading before you blast my posts. This isn't the 90's anymore, engine's evolve.

Your posts deserved to blasted to keep from spreading this "I don't believe this rubber ring can do anything".

Quote:

Originally Posted by 7419sundat (Post 2121618)

Your posts deserved to blasted to keep from spreading this "I don't believe this rubber ring can do anything".

You haven't seen the size of it to fully understand. It will rot out well before the engine breaks. Is the motor going to explode when that happens? I'm pretty sure it won't. I'll be surprised if it lasts 15k miles before it rots.

Wel maybe I'm off the mileage a bit, but you get the idea.

It didn't on my 74 Z. The outside spun and I had to get a new one albeit almost 40 years later.

Just to clarify for what that rubber ring is for, it's to balance the pulley it's self. I wouldn't doubt it's to assist N/V/H as well, but we all know our engine is not the silkiest around.

Kyle @ Stillen asked Nissan engineers about it on an old thread

"This is a harmonic dampener of sorts, on that point you're exactly right. But it's not to balance the engine, it's to balance the pulley ITSELF."

Okay so what you're saying is damaging harmonics and torsion don't affect the rotating assembly at all, and if it did then auto manufacturers have not developed a solution for it so therefore no need to worry.
And they balance a metal pulley with a rubber ring?
This is what you're trying to convince us of?