the crank shaft its harmonic balance?

DEpointfive0 · 01-19-2013, 01:40 PM

Quote:

Originally Posted by 7419sundat

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.

SouthArk370Z · 01-19-2013, 02:20 PM

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.

lemon-fresh · 01-19-2013, 04:35 PM

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.

XwChriswX · 01-19-2013, 04:36 PM

Quote:

Originally Posted by lemon-fresh

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.

SS_Firehawk · 01-19-2013, 04:32 PM

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

7419sundat · 01-19-2013, 06:11 PM

Quote:

Originally Posted by SS_Firehawk

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

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?

SS_Firehawk · 01-19-2013, 07:48 PM

Quote:

Originally Posted by 7419sundat

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.

Red__Zed · 01-19-2013, 09:35 PM

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

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.

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

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

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

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.

reldas · 01-20-2013, 10:06 AM

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.

7419sundat · 01-20-2013, 10:56 AM

Here's some interesting literature... ATI - The Dangers of Power Pulleys & Understanding the Harmonic Damper

7419sundat · 01-20-2013, 11:14 AM

http://www.bhjdynamics.com/downloads...amper_Info.pdf

SS_Firehawk · 01-20-2013, 03:48 PM

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.

7419sundat · 01-20-2013, 07:09 PM

Quote:

Originally Posted by SS_Firehawk

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.

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...

SS_Firehawk · 01-20-2013, 07:43 PM

Quote:

Originally Posted by 7419sundat

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...

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.

edub370 · 01-20-2013, 03:53 PM

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

01-19-2013, 02:20 PM	#2 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	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. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

01-19-2013, 04:32 PM	#5 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	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 XwChriswX and DEpointfive0 like this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

01-20-2013, 10:06 AM	#9 (permalink)
reldas Base Member Join Date: Aug 2011 Location: Sydney Posts: 144 Drives: 09 Nissan 370z auto Rep Power: 14	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. vitinvictor1 likes this.

01-20-2013, 03:48 PM	#12 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	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. XwChriswX likes this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

01-20-2013, 03:53 PM	#15 (permalink)
edub370 A True Z Fanatic Join Date: May 2011 Location: KCMO Posts: 3,458 Drives: 09 370z S/T 6MT Rep Power: 21	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 UFreefer likes this. __________________ 09 370Z ST 6MT//Injen CAI//Greddy CBE//TP//TSW's//Swifts//Stillen lip//Whiteline sways 326whp/268tq

01-19-2013, 04:35 PM	#3 (permalink)
lemon-fresh Enthusiast Member Join Date: Mar 2012 Location: Calgary Age: 40 Posts: 471 Drives: 09 370z Rep Power: 14	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.

01-20-2013, 10:56 AM	#10 (permalink)
7419sundat Base Member Join Date: Aug 2011 Location: colorado Posts: 145 Drives: 09 370z Gtm TT 2 Rep Power: 14	Here's some interesting literature... ATI - The Dangers of Power Pulleys & Understanding the Harmonic Damper

01-20-2013, 11:14 AM	#11 (permalink)
7419sundat Base Member Join Date: Aug 2011 Location: colorado Posts: 145 Drives: 09 370z Gtm TT 2 Rep Power: 14	http://www.bhjdynamics.com/downloads...amper_Info.pdf

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