Destroying the dogma: lightweight crankpulleys

[i3igpete]

http://www.scribd.com/doc/17767722/Vibration-dec-0508

a short and concise presentation.

-a torsional damper (OEM crankpulley) is not the same as a isolator (rubber engine mount)
-engine balance (centrifugal/reciprocating loads that add up to engine vibration) is not the same as a crank twist

[txq45]

Recently torn down a engine that had the lightweight under drive pulley...After inspecting the main caps and crank it was determined that the crankshaft had been walking, everything was balanced on the bottom.. The engine was a VG30DET.. We rebuilt the engine and installed a ATI racing damper.. a little heavier but gives the engine a longer life...

[Ultimate]

Good post, I liked it on 3stech too.

[Trab]

Does anybody know where i can find one to replace my old lightweight pulley? The thing worries me....

[Intropy]

Now if only we had some good products available. :(

[Trab]

Im trying to find my stocker, im in the middle of putting my third engine together and i dont want to use this same pulley again, i have a old IPO one and it looks and feels really cheapo.

[Unknownvr4]

So, would having a lightweight flywheel on the other side yet again (in theory since you now have less weight on one side) unbalance the crank?

[marshallh]

So, would having a lightweight flywheel on the other side yet again (in theory since you now have less weight on one side) unbalance the crank?

http://img251.imageshack.us/img251/2287/96817383.png

From what I understand the torsional damper (rubber ring) in the OEM pulley is to prevent vibrations shown in the picture from building up.

Imagine you are playing guitar, and then someone lays a towel over the strings. You hear very little sound because the strings then hardly vibrate beyond the initial wave, because the towel is a damper.

It doesn't take very much material to prevent resonation from building up. That is what the rubber ring does.

Again, this kind of buildup occurs mostly at constant engine speeds (cruising, etc), but still happens to an extent under all conditions.

Pete if any of this needs fixing let me know, this is how I currently understand it.

[tachyon]

http://www.scribd.com/doc/17767722/Vibration-dec-0508

a short and concise presentation.

-a torsional damper (OEM crankpulley) is not the same as a isolator (rubber engine mount)
-engine balance (centrifugal/reciprocating loads that add up to engine vibration) is not the same as a crank twist


OMG... the first "underdrive vs. OEM" crank pulley post! The new forum is now official!!

Thanks, Pete. But IDK that this will end the debate any time soon. ;)

Oh, and for the record... I've always been on the side of OEM harmonic dampers.

[mb7050]

Shit I just installed my 3sx lightweight crankpulley to replace the OEM one(which was by the way in perfect condition) now I come here and see this FUCXK

[Tackhammer]

I have the only dampened underdrive pulley in existence.................. Let the bidding war begin

[green-lantern]

Now if only we had some good products available. :(

There is a good lightweight dampener out there but the problem is it's like 800 bucks or something.

[Tackhammer]

Just so you know what your bidding on.............

http://i742.photobucket.com/albums/xx66/TopGearEngineering/MVC-001S.jpg

http://i646.photobucket.com/albums/uu190/thebatmovile/picsgifs/heehee-1.gif

[Ninja Performance]

I will only run and recommend OEM dampners on higher HP (500+) cars.
That is all that I will run on my car.

Wish Fluidampner made one for us :(

-Chris

[mb7050]

^^how much is the starting bid ??:D

[Tackhammer]

One Million Dollars :p

[EvanH]

How about seeing what fluidampr would charge for a group buy????? I wish there were ones better than stock. Though I just bought a new OEM one.

[ChargerX3]

Glad to see this thread copied over from the "other site". Once again x2 for fluidampr.

[Vince86]

Maybe thats why i get a drip once in a while from my crank seal... its brand new too. fml

[MaxClass]

I have one of the 3SX aluminum standard sized pulleys.

Does this mean that I should stay with the factory dampener on my 500hp build instead of the 3SX one?

[Trab]

Maxclass, i think that you should sell me your stocker. lol Nah if i was you i would reuse my stock one.

[green-lantern]

Just so you know what your bidding on.............

http://i742.photobucket.com/albums/xx66/TopGearEngineering/MVC-001S.jpg

http://i646.photobucket.com/albums/uu190/thebatmovile/picsgifs/heehee-1.gif


yeah that's it. :p

[Tackhammer]

That one is/was made by Fischer
I was a dealer back in the day and tried to do a group buy @ $350 and was quickly laughed out of my own thread
I said screw it, got one for myself, and never mentioned it again

[i3igpete]

http://img251.imageshack.us/img251/2287/96817383.png
Again, this kind of buildup occurs mostly at constant engine speeds (cruising, etc), but still happens to an extent under all conditions.


This picture here is a bit misleading. the vibration shown here is a bending mode, which is usually the 3rd or 4th natural frequency (very high Hz), and is basically impossible to tune out. This is fine since each vibration mode has progressively less excitation.

One thing to note that these papers don't mention is that resonance builds up quickly. From steady state unloaded crank it only takes 5-6 engine cycles for the crank to reach vibrational convergence. at 6000 RPM that works out to be just 0.05-0.06 seconds. The problem is that in reality, the crank is already vibrating quite a bit at 5800 and 5900 rpm.

The string analogy is good, but a better analogy for those with a musical background is a brass instrument. the vibration gradually gets drops off at slightly higher or lower RPMs - it's not an on/off switch. for a given overtone, although you may be playing the right fingering on the trumpet, you may be flat or sharp due to your lip buzz frequency.

[TonyM]

How about seeing what fluidampr would charge for a group buy????? I wish there were ones better than stock. Though I just bought a new OEM one.

I had contacted ATI about making one but another member at 3Si had already been doing the same for some time prior. I let it go at that point and he hasn't posted any updates since. It really shouldn't be too difficult for ATI to reproduce a streetable damper for the 6G7X as they've done speciality one-offs for drag cars in the past.

Expect pricing for something like this to be at least $750 plus the machine work to have the hub pressed on to you crankshaft. It's not a cheap mod but would be beneficial for the big dollar builds where you have thousands wrapped up in the bottom end.

[bluemax_1]

Well, if the article is correct that viscous type dampers are better than the elastomeric dampers (and elastomeric dampers optimally need tuning with the elastomer durometer etc.) who's going to approach Fluidampr about making a pulley for us? Especially since it appears the ATI thing stalled out and is dead in the water.


Max

[EvanH]

One of the big guys. Sponsors?

[RL7]

The belts are rubber. Don't they have some dampening ability? The rubber strip in the oem pulley isn't much larger. I'm currently using a lightweight pulley, but that's only because my oem ones were chipped. I also saw pics of oem pulleys that came apart at the rubber and it didn't look like a fun thing to have happen. Those failed oem pulles were undoubtedly very old though.

[DanF]

Nelson had ATI make some Super Dampers for his engines. Of course that's hardly an affordable solution.

[i3igpete]

in a word, no. consider the thickness of the rubber ring and the shear surface area - overall, it is very stiff because it's tuned to match a vibrating piece of steel. then consider a length of timing belt or accessory belt - a very long piece of rubber with very small cross sectional area. it is so soft that it is basically ignored by the vibrational torques in the crank - typically 4-6 times that of the output torque (thats 1200-2000+ ft-lbs of twist that the journals see)

[RL7]

I figured the effect of the belts would be negligible, was just wondering. I'm thinking if you go back to the guitar analogy, it would be like putting a piece of paper on the strings rather than a towel. Just out of curiosity- is there ANY modern engine that comes from the factory without some sort of harmonic balancer?

[Hard AttacK]

Fuuuuuuuuuuuuuuuuuuuu

[Trab]

O well i got me a stocker coming YAH

[J. Fast]

Very interesting article. I would have to question wether problems with dampener failures are also stemming from an out of balance counterweight on the other end of the crankshaft, the flywheel. My interpretation of the article is the the harmonic resonance thru the crankshaft can be reduced if you have a properly weighted and balanced flywheel. So what happens if the flywheel is cut and not properly balanced or you install a clutch that slowly strips away flywheel material causing an uneven wear pattern on the flywheel?

The second thing I also noticed is the crankthrow points of defection are also suspect as they have seperate modulus if different friction producing materials are utilized at each pivot point and each adjoining point. When engines get old they shed bearing and ring material aswell and if the material being utilized is not uniform it's possible to also increase the resonance. Page 22 illustrates the stress analysis on the crankthrow pivoting locations. Depending on the frictional coefficients and usable life of the material the harmonics in an engine can also change the deflection rate which affects balance.

If you're flywheel is weighted and balanced properly, your engine is properly balanced and has clamping surfaces with the same modulus, and you're within radial and lateral runout specs I would disagree that a harmonic balancer is necessary. If all moving parts are held to tight to weight and balance specifications and you prevent vibration stackup a solid is probably fine.

30K miles with around 700 ft/lb at the crankshaft on an Unorthodox and no harmonic problemos here.

One other thing I noticed in the article was resonance and harmonic waves on the drivetrain. Kinda had me thinking about problems with exploding drivetrain parts. The lower the harmonic resonance in a tortional rotating assembly, the less damage you cause.


Really cool article Pete,

Jeremy

[i3igpete]

Very interesting article. I would have to question wether problems with dampener failures are also stemming from an out of balance counterweight on the other end of the crankshaft, the flywheel. My interpretation of the article is the the harmonic resonance thru the crankshaft can be reduced if you have a properly weighted and balanced flywheel. So what happens if the flywheel is cut and not properly balanced or you install a clutch that slowly strips away flywheel material causing an uneven wear pattern on the flywheel?

The second thing I also noticed is the crankthrow points of defection are also suspect as they have seperate modulus if different friction producing materials are utilized at each pivot point and each adjoining point. When engines get old they shed bearing and ring material aswell and if the material being utilized is not uniform it's possible to also increase the resonance. Page 22 illustrates the stress analysis on the crankthrow pivoting locations. Depending on the frictional coefficients and usable life of the material the harmonics in an engine can also change the deflection rate which affects balance.

If you're flywheel is weighted and balanced properly, your engine is properly balanced and has clamping surfaces with the same modulus, and you're within radial and lateral runout specs I would disagree that a harmonic balancer is necessary. If all moving parts are held to tight to weight and balance specifications and you prevent vibration stackup a solid is probably fine.


what you have to remember is that once the clutch is engaged any balance issues from the flywheel disappear, since you are also now supported by the transmission bearings. similarly, recall that lateral runout causes euler bending forces and radial runout causes centrifugal forces - not the same as torsional. excessive runout in an engine with a torsional damper will still grenade.

you are correct that as bearings age, they affect friction. in industry this is modelled as absolute damping - think of it as a damping term applied to the journal that is a function of engine speed. however, the mechanics of how the crank damper is tuned does not change. recall that any forces on a frequency domain system are called forcing functions - they don't change the system itself, but rather the right hand side of the ODE*. that means that the tuning of the damper does not change with age of the bearings/friction.


*ordinary differential equation:
http://upload.wikimedia.org/math/5/5/c/55c1ba834865d8d0050f85f65a88deb4.png

[J. Fast]

you are correct that as bearings age, they affect friction. in industry this is modelled as absolute damping - think of it as a damping term applied to the journal that is a function of engine speed. however, the mechanics of how the crank damper is tuned does not change. recall that any forces on a frequency domain system are called forcing functions - they don't change the system itself, but rather the right hand side of the ODE*. that means that the tuning of the damper does not change with age of the bearings/friction.
I understand the tuning of the dampener will not change. However if your engine is designed with low resonant frequencies and the vibration ampitudes are low then there is no reason for dampening it.

Another example the article never really addressed is over-tuning and under-tuning a dampener which has to do with shifting the amplitude vs. frequency curve position in the rpm range (page 40). You can add weight or take it away from the balancer and can shift the peak amplitude vs. frequency position to an area that a vehicle will rarely operate in.

Jeremy

[i3igpete]

actually, what is more common for motorsport applications where no crank damper is used is to stiffen the crankshaft as high as possible. this increases the natural frequency sufficiently high that the max rpm (and thus firing frequency) aren't high enough to excite it. for example, the sports prototype crank i'm working on right now has severely underbalanced counterweights. This reduces the inertia, and thus increases the first natural frequency.

they have sacrificed in-throw balance in order to not need a crank damper. i should mention here that in-throw balance is not the same as the summed balance - summed balance is what you feel and remains the same because it only depends on engine configuration.. in throw balance is the balance between two given journals.

[UTRacerX9]

30K miles with around 700 ft/lb at the crankshaft on an Unorthodox and no harmonic problemos here.

Jeremy

I've got nearly 50k miles on my engine using lightweight flywheels and crank pulleys... no problems. I had an Unorthodox on there for 40k of it, but I got tired of my headlights flickering when at idle sometimes, so I put a 3SX stock sized one on about 10k ago. I've had a UR flywheel for that same time period also.

Honestly, I still can't believe people argue about this, it comes down to personal preference. I prefer having a lighter rotating assembly, and sticking with a td04 based turbo, running a max of 18-19 psi. Far more people have blown up their engines due to overboost conditions than have ever screwed up an engine due to ditching the harmonic balancer.

[92RT-TT]

After the things I've read I dont think I'd ever put a lightweight crank pulley on.

[Vince86]

I've got nearly 50k miles on my engine using lightweight flywheels and crank pulleys... no problems. I had an Unorthodox on there for 40k of it, but I got tired of my headlights flickering when at idle sometimes, so I put a 3SX stock sized one on about 10k ago. I've had a UR flywheel for that same time period also.

Honestly, I still can't believe people argue about this, it comes down to personal preference. I prefer having a lighter rotating assembly, and sticking with a td04 based turbo, running a max of 18-19 psi. Far more people have blown up their engines due to overboost conditions than have ever screwed up an engine due to ditching the harmonic balancer.

Amen.

[Trab]

Im sure that even more people have blown up there engines due to not having oil... But that doesnt really prove anything...

[Atrosity]

This is the reasons why I won't change out my crank pulley. I won't even change out my driveshaft just because it is pointless.

[Ninja Performance]

I've got nearly 50k miles on my engine using lightweight flywheels and crank pulleys... no problems. I had an Unorthodox on there for 40k of it, but I got tired of my headlights flickering when at idle sometimes, so I put a 3SX stock sized one on about 10k ago. I've had a UR flywheel for that same time period also.

Honestly, I still can't believe people argue about this, it comes down to personal preference. I prefer having a lighter rotating assembly, and sticking with a td04 based turbo, running a max of 18-19 psi. Far more people have blown up their engines due to overboost conditions than have ever screwed up an engine due to ditching the harmonic balancer.

Sounds like your setup is "low power", which I don' t have a problem with using a non OEM pulley. Once you are over 500-600AWHP, I would highly recommend it.

-Chris

[UTRacerX9]

The power of the car has little to do with it. I've been running 13T's for years, and they put out decent power, I've got a 19T sitting in a box waiting to be installed because I wanted to do a 13/19T combo. My goal has always been 11.7 or thereabouts, so no need to go with a td05 setup.

My car still spins to a 7k redline, and if harmonic balancing is what we are debating here, it makes little difference how much peak power an engine can put out, what matters is whether the engine is balanced or not. For 50k miles, I for one have had no problems, and I don't baby my car when I drive it. I suspect most people who have had an engine failure and blamed it on a crank pulley would have lost their engine with the stock pulley too, for whatever reason.

[i3igpete]

The power of the car has little to do with it.

My car still spins to a 7k redline, and if harmonic balancing is what we are debating here, it makes little difference how much peak power an engine can put out, what matters is whether the engine is balanced or not.

no, power has EVERYTHING to do with it. harmonic balance is twist of the crankshaft. twist is torque - power depends on torque and RPM. if you'd read what i wrote before, typical vibration torque (TWIST) can be 4 or more times the brake torque. 500 ft lbs going out the clutch = 2000+ ft lbs of torque at the journal.

balance is centrifugal force. centrifugal force depends on counter weight.

they are two completely different things.

saying "my car is fine" is one thing. but please don't mix up concepts - it's very misleading to owners that don't know any better. centrifugal force and torque are two very clear, very different things.

[bluemax_1]

What I personally wonder about is how much difference it would have made to the high HP cars running undamped pulleys, as to when they begin developing cracks in the journals. I recall reading about those cars a few years back when there were a lot more people saying, "undamped pulleys are fine" before a few of us began bringing up the difference between balanced and damped.

Heck, IIRC, more than a couple of owners didn't even realize their journals were cracked till they did a preventive teardown and magnafluxed the crank. Of course, I think there was at least one that found out when they broke the crank.


Max

[J. Fast]

no, power has EVERYTHING to do with it. harmonic balance is twist of the crankshaft. twist is torque - power depends on torque and RPM. if you'd read what i wrote before, typical vibration torque (TWIST) can be 4 or more times the brake torque. 500 ft lbs going out the clutch = 2000+ ft lbs of torque at the journal.


To an extent, but not entirely. As the article summarized... it has very little to do with power, but the design and relationship between the pistons, rods, crank, and material coefficients. If you change the mass or frictional coefficients of any these items in an engine you will change the natural frequency of an engine. It would be an absolute miracle to see a 6g72 engine with Pauter rods, Wiseco pistons, and and custom fit bi-metal or tri-metal bearings, produce the same natural frequency on the same crank, it's just not going to happen. The crank is still going to twist and you will experience torsional vibration but the natural frequncy must and will change.

If you modify your engine from stock, an oem dampener serves no purpose, the natural frequency of your engine will be different then stock so what purpose does a stock dampener even serve? Since the stock balancer is designed with a specific vibration frequency in mind, with a modifeid engine you are just as well off without one. (until fluidampr makes us one :) )
From the lips of Jack Kane (RET) Race Engine Technology, SAE, AAMI Design Development Engineering:


" One aftermarket device, the Fluidampr™, is an example of a damper. It dissipates energy by transforming it into heat by shearing action in a high viscosity fluid. Some race car people seem to like it, but it is banned from the top levels of NASCAR racing, because with extended use at high levels of energy dissipation, the polymers in the shearing fluid become rearranged and the fluid then settles off-center when the engine is stopped. Next time it is run, the nose of the crank is horribly out of balance, and there's a short run from there to cranksaft failure.

...modifications to an original engine design which affect crankshaft stiffness and / or system MMOI (stroke, counterweights, bobweight {therefore counterweight} mass, clutch and flywheel MMOI, etc) will change the system resonant frequency. In order to determine the correct solution for a particular engine combination, the engine designer must a) do the measurements to determine the critical frequencies in your application and (b) and design or obtain an absorber tuned for the correct order or frequency, as fits with the application.

For any application which operates at high power and a relatively constant speed for long periods (unlike a race engine which typically cycles up and down quite rapidly and only has to live a few hours), it is critical that the major orders of crankshaft torsional vibration be attenuated.

Whatever device is used to absorb crankshaft internal torsional vibrations, it has an effect (usually small) on the excitation produced at the loaded end of the crankshaft around resonance. That device, together with the Mass Moment of Inertia of the devices attached to the output flange of the crankshaft, will affect not only the value of the crankshaft resonant frequency, but also will influence the longitudinal location of the torsional node on the crankshaft.

The fact that a crankshaft is running through a wider RPM band and doing so rather quickly suggests that the crankshaft doesn't spend much time at any critical frequency. The bigger issue with crankshaft torsionals in a high performance engine is the level of excitation into the valvetrain, which detracts from the accuracy of valve motion.


Jeremy

[MaxClass]

So you are saying that once you go forged pistons [mine are Wiseco’s] and other mod’s you have actually changed the frequency of the whole system? That makes sense to me.

Then if the stock pulley is designed for the stock frequency system and you change it then you have a whole new ballgame. I had the machine shop balance the works with aluminum pulley and flywheel I plan to run so it should be better than using the WAG approach. If not I would appreciate any additional input on this subject from anyone knowledgable on this stuff.

It’s not a matter of life or death, it’s more important than that.

It also sounds, if I’m getting any of this, like how strong the frequencies are are also dependent upon the amount of power directed into the system at any one time. Seems like cruising along at 2500 rpm’s pulling vacuum should not induce a lot of frequency problems until you get on it, then the twisting really begins as the rpm’s go up and additional frequencies are encountered.

I find this a fascinating discussion. Something like what you would find on 3STech.

Is this compatible with "String Theory"? Michio Kaku didn't mention this in any of his books.

[pos-vr4]

Think about your common "power pulleys." They may add some power by slowing down all of your accessories, but they will hurt your engine life and your power at some RPM ranges. Power Pulleys are not the right way to make power. In the long run power pulleys will yield failures in your engine and components on your car. That stands true for Imports and American cars. Read more about the Dangers of Power Pulleys on ATI's web site, www.atiracing.com.






I found this expert out of an ATI article from last year

IMO neither an OE pulley or a power pulley is BEST for a big power 3s application, but a New OE pulley would be the prefered way to go with what we have to work with.

[J. Fast]

So you are saying that once you go forged pistons [mine are Wiseco’s] and other mod’s you have actually changed the frequency of the whole system? That makes sense to me.

Then if the stock pulley is designed for the stock frequency system and you change it then you have a whole new ballgame. I had the machine shop balance the works with aluminum pulley and flywheel I plan to run so it should be better than using the WAG approach. If not I would appreciate any additional input on this subject from anyone knowledgable on this stuff.

It’s not a matter of life or death, it’s more important than that.

It also sounds, if I’m getting any of this, like how strong the frequencies are are also dependent upon the amount of power directed into the system at any one time. Seems like cruising along at 2500 rpm’s pulling vacuum should not induce a lot of frequency problems until you get on it, then the twisting really begins as the rpm’s go up and additional frequencies are encountered.

I find this a fascinating discussion. Something like what you would find on 3STech.

Is this compatible with "String Theory"? Michio Kaku didn't mention this in any of his books.

I think the most important thing to remember is every engine is different. As soon as you change the weight or composition of one component tied to the crank, the natural frequency will change aswell as the 3rd order or 4th order frequency being discussed. Therefore a dampener will only work if designed for each unique engine. Just don't go driving around at a constant 5000 rpm's for a 1/2 hour. Run through the gears.

Jeremy

[MK_94_3000GT]

I have the only dampened underdrive pulley in existence.................. Let the bidding war begin

False, I have one too :p

[i3igpete]

To an extent, but not entirely. As the article summarized... it has very little to do with power, but the design and relationship between the pistons, rods, crank, and material coefficients. If you change the mass or frictional coefficients of any these items in an engine you will change the natural frequency of an engine.

If you modify your engine from stock, an oem dampener serves no purpose, the natural frequency of your engine will be different then stock so what purpose does a stock dampener even serve? Since the stock balancer is designed with a specific vibration frequency in mind, with a modifeid engine you are just as well off without one. (until fluidampr makes us one :) )



you have a valid point - changing the mass/inertia of the system does change the natural frequency, and yes, this needs to be tuned for. i never said it didn't and the presentation mentions it as well. I can post the tuning methodology from my own notes well. you are incorrect that a slightly mis-tuned damper does "nothing". it still works, just not as perfectly as it should - see the page on undertuned or overtuned dampers.

however, the power output of the crank is directly related to the stress imposed on the system; it is the forcing function. UTracerX was saying that the power did not matter. It does because as you increase power things you could "get away with" before, no longer work. again, you are not changing the system, but you are changing the loads and therefore the corresponding stress. recall from your vibrations class that when designing a damper, you are changing the free vibrations of the system (the eigenmodes, which have unitless vibration amplitudes). the forced response (the real, measurable response) depends on the free system and the loads applied to it.

edit:
while looking thru my notes, i see that i have points on how to tune a fluid damper. i'll post this as well.

[J. Fast]

i see that i have points on how to tune a fluid damper. i'll post this as well. Love to see the notes, any chance you can post any info on possible variations of destructive htz ranges with differing rod and piston weights on our crankshafts? I can send you some info on my wrist pins, rod bolts, rod, and piston weights / composition, etc.

Jeremy

Edit: hell everyone should throw some info in there and run some different scenario... how cool would that be.

[UTRacerX9]

UTracerX was saying that the power did not matter.

No, what I said was...


The power of the car has little to do with it.
My car still spins to a 7k redline, and if harmonic balancing is what we are debating here, it makes little difference how much peak power an engine can put out, what matters is whether the engine is balanced or not.

I'll take the reduced stress on the engine from less rotational weight than worry about a dampener that was originally designed for a 9b, heavy flywheel car.

[i3igpete]

here's the thing though, on an engine, rotational weight has no effect on the crankshaft unless you mean centrifugal (unbalanced) loads. a heavy flywheel and a light flywheel are the same thing unless it is unbalanced (and makes centrifugal force).

again, torque and unbalanced force are two different things. one is a twist, the other a shove. Both act on the crankshaft in different ways.

Jeremy,
the notes on the fluidampr are page 5.

Another fun point is that people don't realize that it's possible to tune a crank with a solid pulley (page 2). Though it's nowhere near as good as with an elastomer, there is a more subtle kind of takeaway point: a crankshaft with a solid welded steel pulley would actually protect your engine better than a aluminum pulley.

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[UTRacerX9]

I'll admit I'm no engineer here, but I damn sure can tell that having a light flywheel and my old stock heavy one did indeed affect the operation of the crankshaft! The stock flywheel allowed the engine to slowly return to idle after being revved. With the UR one, my rpms drop like a rock. It takes more energy, (and thus more work) for my crankshaft to turn the heavier flywheel, and the same principle would hold true for the crank pulley, it just is not felt nearly as much.

Here's my non-engineer example. Say I have a toothpick. I stick a piece of round cheese on the end of it. I turn the toothpick with my fingers and the cheese rolls back and forth. Take the same toothpick (crankshaft) and stick it to a heavy rock. I turn it, and it takes a lot more force to move it, in fact, I may break it.

As I stated originally, it comes down to personal preference. I KNOW my engine spins to redline faster than a comparable turbo car with a stock flywheel and pulley. My engine has to work less to turn. Now, am I possibly doing some harm to the engine by not having a harmonic dampener? Sure, that's why they are there. But my point is that I've never seen ANYTHING proving how much damage it may be doing vs the benefits of having a lighter drivetrain. And in my case at least, we're talking 50k miles with upgraded turbos, the underdrive pulley and the UR flywheel. If it's made it that far (now having 91k on it) with no issues, that to me says that it is not doing enough damage (if any) to warrant removing it.

[i3igpete]

Actually, your toothpick in cheese is a good example. let me expand on it and explain how a torsional damper works.

Imagine that the cheese wheel is your flywheel, transmission, and vehicle body. for all intents and purposes it is - the time scale between a torsional vibration (~10 vibrations per engine cycle), and the number of cycles per second (6000rpm = 100 engine cycles per second), means that reducing the weight of the flywheel is relatively insignificant. The crankshaft vibrates so many times per second that reducing the drivetrain inertia or vehicle body has no effect on the vibration of the crankshaft. the time scale is completely different - a crank vibration is a snapshot compared to a run down the drag strip.

now, let take a look at cheese wheel example in a different way. say you apply the torque to that tooth pick until it snaps. what if there was a cheese wheel on the other side of the toothpick? if you grab the toothpick in the middle now, it will probably take more torque to break, right? That is how a solid (heavy) disk tunes a crankshaft. It adds inertia to the front end of the crankshaft, so that both ends are stuck into a cheese wheel. torques get absorbed in two directions, meaning that the total twist in the toothpick is less. however, the total output torque going out the clutch is the same, because the cheese wheel pulley is a dead end. there's nowhere for it to go.

Now, I'm not saying that a damper is always needed in every situation. I can think of plenty of normal applications where the crankshaft is relatively stiff/strong compared to it's output torque. Small engines like harley engines or small NA engine cars like civics can get along just fine without one. We have a relatively large crank. Lightweight pulleys are fine for SOHC and NA/DOHC applications on our cars, because they don't have as much torque pulsing through the crank. as brake horsepower goes up, so does the output torque thru the clutch, and so does the vibrational torques in the crank.

[UTRacerX9]

I see what you're saying. The vibration of the crankshaft though, to me is somewhat inconsequential. You just said yourself that reducing the weight of the flywheel is relatively insignificant, so why then do you make the argument that having a lighter pulley is significant and bad for the engine? You can't have it both ways...

For your second paragraph, I also see what you you are getting at, and agree. However, by lightening both the front wheel of cheese, AND the rear, total twist should remain somewhat in proportion. (In fact, the flywheel I have is supposed to be about 40% of the weight of the stocker from what I remember, and the 3SX pulley was about 33% the weight of stock I think.) So... still not seeing why a lighter pulley is a bad thing.

[i3igpete]

here's the thing though, you "can't" reduce the rear wheel of cheese because that is the transmission, driveshaft, and vehicle moving thru the air. no matter how light you can get the car, drag force is always there, making that rear cheese wheel grow bigger and bigger as you speed up. it will never go away.

[UTRacerX9]

Good point... Hmm. We need a thumbs up smiley...

[Polygon]

This has been a very good read. I've never been a fan of light weight pulleys. I don't see the point in such a risk for the marginal benefits.

Now, I have to ask, can we still get the OEM harmonic dampener beyond buying them used?

[jba3]

This is all quite above my head, so hopefully I can ask a simple question. I have an underdrive pulley on my car. I've had it for about 35k, and IIRC from the receipts, it was installed about 40k before I bought the car. It's currently at 135k miles. I also have a lightweight flywheel (I think). Does that mean it's somewhat "balanced"? I am running the stock 9Bs with the normal bolt-ons, at 14psi. I have not had any issues (replaced a starter and alternator) in those 35k miles.

When I pull the motor for the 120k service, should I go with an OEM one instead, or is the underdrive acceptable since I have the lightweight flywheel as well?

[J. Fast]

Just so happens I came acorss a harmoic balancing issue today and figured I post up.

This is a stock harmonic balancer and timing sprocket for an EVO.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Colorado3s/Photo_092110_005.jpg
http://i788.photobucket.com/albums/yy163/JFastMotorsports/Colorado3s/Photo_092110_008.jpg


This is the same stock harmonic balancer for an Evo on a modified engine.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Colorado3s/Photo_092110_004.jpg
http://i788.photobucket.com/albums/yy163/JFastMotorsports/Colorado3s/Photo_092110_006.jpg

The two side by side...

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Colorado3s/Photo_092110_009.jpg

You can see where the harmoic frequency resonated thru the crankshaft and caused the sprocket to dig into the harmonic dampener.

A stock harmonic damper will not protect your engine. The natural frequency is on a different Hz rating with different weight on the crankpins. If you have a modified engine make sure you doublecheck your stackup and dynamic balance. This is a perfect example of why a stock dampener should not be used in conjunction with a modified engine...

Jeremy

Jeremy

[pos-vr4]

well, thats to say if the 6g72 had a better option we could. as it is the OE damper only neutralizes a very small range anyway, and after a change of internals its range of operation is even smaller.

What do you know about the "modified" Evo engine?? was it rebalanced after the internals were changed?

[i3igpete]

modified in what way? this would only be a valid comparison if both sprocket/pulleys were out of engines with the same power output, but different reciprocating assemblies. if the power has been upped in the "modified" engine, this is not a valid comparison. the increase in journal torques would WAYYYY overshadow the slight under/overtuning of the pulley.

[J. Fast]

modified in what way? this would only be a valid comparison if both sprocket/pulleys were out of engines with the same power output, but different reciprocating assemblies. if the power has been upped in the "modified" engine, this is not a valid comparison. the increase in journal torques would WAYYYY overshadow the slight under/overtuning of the pulley.

Both vehicles are stock ecu, stock everything including stock compression 8.8:1. The only difference between the two is Wiseco pistons, Eagle rods, TOGA main and rod bearings, and Arias wrist pins. Not that it pertains to the discussion but the dampener that's dog shiet is also owned by a 20 yr old... so who -knews'.

Jeremy

[pos-vr4]

Both vehicles are stock ecu, stock everything including stock compression 8.8:1. The only difference between the two is Wiseco pistons, Eagle rods, TOGA main and rod bearings, and Arias wrist pins. Not that it pertains to the discussion but the dampener that's dog shiet is also owned by a 20 yr old... so who -knews'.

Jeremy

Did both engines still have the balance shafts? if the modded car had them deleted that is the kind of harmonic damage one would expect to see.
The change of internal parts would require a rebalance of the lower end.

That IS a big difference in rotating mass for sure. On my 3.1 that i just had balanced had a total bob weight of 780 grams lighter than a OE engine, that is almost 2 lbs difference over a stock engine at 7 k rpm that is tons of out of balance mass.

[i3igpete]

balance shafts do act on the crank harmonic but not in the way you'd expect. they affect the harmonic balance due to their rotational inertia but their main purpose, to cancel engine vibration with centrifugal forces, does not actually affect harmonics of the crank. removing them would make a HUGE difference since they act as high-inertia crank hubs.

[Trab]

The damaged one probably wasn't tightened properly.

Hmmm, my lightweight one looked just like the one pictured above with the crank cog groves in it.

[SkortchGT]

i've always thought it was not a good idea to replace your stock pulley with an aftermarket undampened pulley. horsepower gain is minimal, just not worth it, especially when a crank is absolutely meant to have a dampener on it.

[J. Fast]

I'm suspicious as to wether or not the greater intent of the OEM crank dampener was to extend the life of the bearings. I would throw a educated guess out there and say bearing longevity had something to do with mitsu's dampener design. I'm still not convinced an undampened pulley in a short crank V-6 revving under 7500rpms on a balanced engine is a problem.

Jeremy

[BoostMONSTER]

I'm suspicious as to wether or not the greater intent of the OEM crank dampener was to extend the life of the bearings. I would throw a educated guess out there and say bearing longevity had something to do with mitsu's dampener design. I'm still not convinced an undampened pulley in a short crank V-6 revving under 7500rpms on a balanced engine is a problem.

Jeremy

thats good thought they have been making UD pullies for years and no one blames them for there engine issues its probly soo minimal if any damage to the crank or engine that it doesnt even matter because something else always breaks first i highly doubt that a dampener less pulley will ever do anything drastic to your engine although if it does have negitve affects to the engine that it only will reduce the life of perhaps as u said the bearings

[wraith]

My take is the total opposite of above. I think if the carmaker went to the lengths they did to get the last bit of HP from the engine giving it that two path intake and DOHC setup just to get an extra 22hp more then typical motors of its day, an extra 5 by eliminating an expensive part substituting a simple pulley would have been a no brainer. I am sure testing had shown them that the motor was suffering from a deleterious amount of harmonics and they slapped something on there to keep those levels in check. I would not risk it myself

[mb7050]

thats good thought they have been making UD pullies for years and no one blames them for there engine issues its probly soo minimal if any damage to the crank or engine that it doesnt even matter because something else always breaks first i highly doubt that a dampener less pulley will ever do anything drastic to your engine although if it does have negitve affects to the engine that it only will reduce the life of perhaps as u said the bearings

What I was thinking too first but see these posts from evoforums .





Originally Posted by GTREVO View Post
I have been an early user of underdrive pulleys for many years now but only learnt about the detrimental effects of harmonics in the 4G63 engine not too long ago.

Try replacing bearings every single race like I do and you will know that the problem lies more than just tolerances and balancing. Have been building 2.0 on the DSM's for years now and the inherent bearing problems but thank god I nitrided my cranks ( thus am able to save cranks even with worn out mains) and 2.3 strokers in my Evo 6 which kills absolutely every single mains running only 6 to 7 passes on a single event. And both makes over 700WHP. Both have not run harmonic balancers and without balance shafts. And yes, the engine DOES make a little more vibration without the balance shafts. Funny thing is that while the main bearings are worn out badly, the conrod bearings remain perfect, almost untouched....

Have recently completed a race on the stroker and will remove the main bearings shortly to compare previously on which I have ran no dampener and this time with the dampener. This will at least confirm some how on the effects of the dampener.

Am only relating my experiences with the harmonics that are killing the engine and I don't think Mitsubishi would be putting one on if it didn't need one...

If I recall in one of many early forums some long time ago, even Bushur runs the stock dampener and doesn't use pulleys....
Read more at http://forums.evolutionm.net/evo-engine-turbo-drivetrain/465494-lightweight-crank-pulleys.html





Originally Posted by GTREVO View Post
Sorry for my late reply on my findings with my motor. Took it apart yesterday and the results are indeed very interesting. After running at over 8000 rpms on this stroker 2.3 motor and at 35 psi making 750 WHP/656 ft/ib WTQ, the bearings were in good reasonable condition and take note, this motor was run WITH a brand new stock Mitsubishi harmonic damper, crank pulley. I swear what I saw was surprising on what I revved the motor to ( 8500 rpm at times on the track). To add to the topic of balance shafts, this motor was built without balance shafts at all. The motor has seen done 40 dyno pulls and 10 full on passes down the track at the drags..

On my earlier post, I mentioned that the mains were worn right down to metal at a lower power level ( 670 WHP) and at less rpms at the track. This was on a brand new rebuilt motor with only 7 passes down the track and about 30 dyno pulls.

The above findings I found was on the same motor except that I replaced a set of brand new Clevites on it and the new Mitsubishi crank pulley and I was all ready to replace it again yesterday but hey there you go guys.... there is no dispute that the damper is there for a reason and for a very good reason in fact.... no more aluminium pulleys for me...
Read more at http://forums.evolutionm.net/evo-engine-turbo-drivetrain/465494-lightweight-crank-pulleys.html




Originally Posted by GTREVO View Post
The engine was pulled apart and I can say that my mixture was perfect since there was ZERO detonation and the pistons and combustion chamber was in perfect condition. I was running the 37R with this and there was no tune difference except that it was maybe .2 of an A/F leaner with the C16.

It's all in the crank damper. I have been using the aluminium underdrive pulleys for the last 10 years and I never had an engine failure with it but it now explains why I have less life span in my motors especially big power and boost is concerned.

It was Carmela from Jackson's that warned me against using a pulley. I took her word and there we go...the difference is obvious especially in a 2.3 stroker.
Read more at http://forums.evolutionm.net/evo-engine-turbo-drivetrain/465494-lightweight-crank-pulleys.html




Originally Posted by GTREVO View Post
Apparently the aftermarket dampers work at all rpms whereas the factory piece is more ' tuned ' at a higher rpm. This is what I was told and I have recently purchased a Fluidamper for my Evo and it is an awesome looking piece, bit heavy though but what the heck, it saves my motor...

There you go guys, guess most of us found out the hard way...even myself..
Read more at http://forums.evolutionm.net/evo-engine-turbo-drivetrain/465494-lightweight-crank-pulleys.html




Originally Posted by GTREVO View Post
Well, after building and playing around with DSM and Evo motor for years now, hate to say this but...I am still learning something new everyday...

Hope my findings will help lots more people out there by keeping their harmonic balancers instead of pulleys...
Read more at http://forums.evolutionm.net/evo-engine-turbo-drivetrain/465494-lightweight-crank-pulleys.html


http://en.wikipedia.org/wiki/Harmonic_balancer

http://www.fluidampr.com/HOWITWORKS.htm

http://www.bhjdynamics.com/downloads/pdf/tech/BHJDynamics_Damper_Info.pdf

[VR4Drive92]

J Fast...

that's not at all why they have crank dampers...

it is there for torsional vibrations... not bearings.

You are dead wrong if you think an undamped crank is a good thing.

[DanF]

Mitch - is that you? Nice post :)

[J. Fast]

J Fast...

that's not at all why they have crank dampers...

it is there for torsional vibrations... not bearings.

You are dead wrong if you think an undamped crank is a good thing.

An undampened crankshaft is fine. The damage only stems from holding a specific rpm and frequency as clearly modeled by the study. Just as the article proves... An undampened crankshaft is fine if you are outside the limits of the 2nd and 3rd order frequency's.

mb7050's post falls pretty much inline with my thought process, the dampeners function is directly tied to bearing wear.

If I make it to 60K on my balancer would it would be a miracle? I serously doubt it as I'm only 15K away fron 60K on this setup and I don't suspect I'll be having any issues.

And what does comparing the charateristics of an inline 4 cylinder crankshaft have to do with that of a v-6? Only proves what my post on the dampener did... Those cars are weak and are always breaking shit. I know because I'm the only one on my race team that doesn't own one... there's 8 on my team. And the only one that has never busted a part or been towed home.

Jeremy

[mb7050]

And what does comparing the charateristics of an inline 4 cylinder crankshaft have to do with that of a v-6?

Jeremy

I knew someone would say this. I was just pointing out that some people do blame ud pulleys...

[GTwizard]

I have been pushing this for so long. All manufactures install them on engines for John Q public for a reason. It needs to be there for normal driving aplications. No matter what the firering order is. I have had an under drive for years and never installed it, As the car was used as a dailey driver and would see periods of sustaind speeds in traffic. But now that I drive the car just for the sole purpose of beating the living day lights out of it, it never sees any RPM at any time long eneough to set up the hermonics needed to cause an issue. Light weight and under drives are for race and other unlawfull activies only. I don't think I even need a tach at this point, It never stops bouncing from side to side. LOL.

[i3igpete]

Don, as I mentioned before, it only needs to stay at the same RPM for ~.05 seconds for the harmonics to fully develop. Even during a 1st gear pull, a crank develops harmonics as the tach sweeps up, just as bad.

[mb7050]

I cant find my stock pulley anywhere where can I buy one if there is no aftermakets available ?
nvrmind
http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=24704

Have anyone contacted fluidamper about making one for our engine I would buy one in a hard beat. group buy maybe, how many would be intrested if the price is right ??

[hotGTO]

I cant find my stock pulley anywhere where can I buy one if there is no aftermakets available ?
nvrmind
http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=24704

Have anyone contacted fluidamper about making one for our engine I would buy one in a hard beat. group buy maybe, how many would be intrested if the price is right ??

You can buy the OEM through Cherry Hill Mitsubishi ... I think I paid like $180
https://www.mitsparts.com/oempartscat.html

And I am glad that some guys with REAL engine building knowledge are posting up the importance of the harmonic balancer! Thanks guys, some of us who know they are important don't have the background to debate the issue!

[mb7050]

Have anyone contacted fluidamper about making one for our engine??

I didnt think it would be that expensive damn.

"The only dampers we carry for the Mitsubishi engine is the EVO 8&9, and the 4G63/T. Attached in PDF customer prints for both these dampers. I am not aware of your engine specs, however, I have had engine builders and machinists modify existing Fluidamprs to fit their application. Due to the amount of engineering and manufacturing in a low production custom application it would not be feasible for a customer to go this route. It may cost upwards of $5000 or more for a custom damper. We do log all requests for dampers we do not produce. If we decide to manufacture this damper you will be contacted by email."

someday they may make a fluidamper for our engine if there is enough interest.

[bluemax_1]

What do the Evo dampers look like? Maybe we could mod them to work?


Max

[mb7050]

here

http://viewer.zoho.com/docs/hCT2d

http://viewer.zoho.com/docs/aCSbZ

http://viewer.zoho.com/docs/vCRdS

or

https://docs.google.com/fileview?id=0BznVddpgdjpMMjg3NWEwZDctOGU0Yi00OTEyL WE0ODYtMDlhZGExYWI5NDE5&hl=en

https://docs.google.com/fileview?id=0BznVddpgdjpMMjVjYjFlNTgtMmI2MC00NGRjL WI1OTktNmRlNTcwN2VjMjJi&hl=en

https://docs.google.com/fileview?id=0BznVddpgdjpMOTQ5NTcwZmEtOTRiYy00MDg1L WIwZWEtYWIwZGJmM2ZhNmE0&hl=en

[mb7050]

http://rossperformanceparts.com/product_range.html

hmm they have few products for 6g72 ... Anyone know are these dampers any good ?

[J. Fast]

From what's been proven from the information provided in the thread. They must be tuned for the natural frequency of each individual engine. Unless everyone in the discussion has the exact same crankpin weights and friction coefficients as their dampener was designed for then it will do you no good.

Their disclaimer...
"Ross Heavy Duty harmonic balancers / crank pulley dampers use the genuine cast iron centres and outer rings which are after being chemically degreased and steel grit blasted, are then assembled and held together with the unique ross tuffbond process.

...ROSS harmonic balancers / crank pulley dampers are specifically designed for direct replacement of... standard production type harmonic balancers."

Plain and simple... they're not a performance upgrade, however, they are a reman'd stock replacement.

Illustration... http://rossperformanceparts.com/heavy_duty_harmonic_balancers.html

Jeremy

[mb7050]

i was thinking maybe the STREET PERFORMER SERIES or even METAL JACKET Harmonic Balancer...



STREET PERFORMER SERIES
Reconditioned Harmonic Balancers / Crank Pulley Dampers

Fit For The Hardest Cornering

ROSS TUFFBOND Street Performer Series Reconditioned Harmonic Balancers / Crank Pulley Dampers are manufactured for over 100 engine types and offer excellent upgrade in reliability and dampening performance for standard or street performance engines.

All Street Performer Series Harmonic Balancers / Crank Pulley Dampers are unconditionally guaranteed against failure for unlimited kilometres up to 12 months from purchase. Street Performer Series Harmonic Balancers / Crank Pulley Dampers sare sold on the exchange basis with deposit charged until core return. Street Performer Series Harmonic Balancers / Crank Pulley Dampers have an attractive finish with easy-to-read ROSS TUFFBOND timing markings and logos.

http://rossperformanceparts.com/imgs/balpics/trip250sp.jpg





METAL JACKET Harmonic Balancers / Crank Pulley Dampers

A World First In Balancer / Damper Design !! Encased Dampener Within Balancers

Introducing a revolutionary development in torsional dampening technology. Utilising the ROSS Tuffbond original elastrometric bonding process to produce the ROSS Metaljacket® series harmonic balancers / crank pulley dampers.

Metaljacket Harmonic Balancers/Crank Dampers designed and manufactured by ROSS.

Metaljacket use the highest spec. 6000 series alloys along with aerospace 7075 hard anodised crankshaft hubs.

Metaljacket is designed to be used on race machines that are driven by enthusiasts on the street, strip,circuit or on the water.

The accessary drive pulley ratios are standard unless requested.

These are the worlds best used by world champions.

* 360 timing marks at 1° intervals
* Adjustable timing disc, for TDC accuracy
* Precision CNC machined 40 Tonne tensile alloy steel hub and vibration dampening ring
* Dampening ring and hub permanently bonded together on TWO axis by our exclusive Tuffbond elastrometric bonding process, ensuring maximum harmful vibrations are absorbed.
* balancer is anodized for durability and appearance
* Absorbs more damaging torsional harmonic vibrations
* Quicker engine acceleration
* Increases engine life
* Lifetime warranty, even for racing use - a world first!
* Never requires maintenance or rebuilding - ever!
* Rated to 1500 HP
* Encapsulated MetaL Jacket® design exceeds AN DRA and SF1 i8.1(USA) requirements
* Fits standard or modified engines
* Affordably priced

http://rossperformanceparts.com/imgs/balpics/mj_exp.jpg
http://rossperformanceparts.com/imgs/balpics/mj_bot.jpg


and for someone looking for a damper for their custom built there is.


MJ RACE Harmonic Balancers / Crank Pulley Dampers

For Circuit & Drag Racing

These are made for racing purposes, and are usually custom designed for top end race engine builders, off the shelf this Harmonic balancer will not always run std pulley belt location.

MJRace balancers/dampers are made from the highest grades of materials that don’t break.

For Naturally aspirated and turbo engines the crank hubs are made from 7075 aerospace alloy.

But in the case of supercharged engines 4340 alloy steel is used for the crank hubs.

The accessory drive pulley ratios are mostly between 10% and 25% underdrive.

This prevents engine overheating , alternator and power steering failures due to overspeed.

These harmonic balancers / crank pulley dampers are made to suit ANDRA requirements and meets sfi rules If your engine regularly sees RPM between 10% and 20% more than standard and you are racing on the track doing multi lap events, using fuel cuts and rev limiters in the programming of your engine, as well as rapid accelleration and decelleration then you will need a race series balancer / damper.

If you are running RB Nissan the balancer / damper has no provision for A/C belt The accessory drive pulleys are mostly underdriven and in some models up to 20%. (Consult catalogue).

Race Series Harmonic Balancers / Crank Pulley Dampers are bonded balancers created for circuit and drag racing applications. Much of the range is instock while customised Harmonic Balancers / Crank Pulley Dampers can also be manufactured to suit individual needs and specifications. The race series may not suit original OEM pulley setups.
http://rossperformanceparts.com/imgs/infopic-race.jpg

[hotGTO]

Ross Performance Metal Jacket:

Mitsubishi.............RB725HD............HEAVY DUTY Harmonic Balancer / Crank Pulley Damper...........6G72 3.0L Pajero & Triton

Would this work on a 3s 6G72??

[mb7050]

From what's been proven from the information provided in the thread. They must be tuned for the natural frequency of each individual engine.
your right but look what they say at fluidamper

"The viscous silicone fluid allows the inertia ring to
shear the harmonic vibration from the engine, regardless of any performance enhancements that have been
made to the engine. This is possible because the Fluidampr is frequency insensitive, able to self tune to the
exact frequency bandwidth of the engine harmonics at any given range."


"SILICONE FLUID IS THE BEST
DAMPING MEDIA AVAILABLE. OTHER
DAMPERS ABSORB VIBRATIONS
THROUGH RUBBER OR MECHANICAL
METHODS THAT HAVE TO BE TUNED
TO EACH FREQUENCY. ONLY
FLUIDAMPR WITH ITS SILICONE
TECHNOLOGY CAN EFFECTIVELY
CONTROL TORSIONAL VIBRATIONS AT
ALL FREQUENCIES.
INERTIA RING"

[J. Fast]

Well make up your mind about which one you want. Do you want a customized dampener or a fluid dampener? You could probably rebuild your engine two times for what it would cost for either of those gems :39: I'z be rollin with the one I has.

Jeremy

[hotGTO]

I like factory replacement for the money....

[i3igpete]

Jeremy, if you revisit my notes here:
http://www.3sgto.org/showthread.php?63-Destroying-the-dogma-lightweight-crankpulleys&p=8199&viewfull=1#post8199

you'll see that damping (and hence, friction coefficients) have no consideration on crankshaft characteristics. The only terms are inertia (I/J) and stiffness (K). damping (C) does not make an appearance, except as a damper tuning parameter.

[bluemax_1]

So Pete, any leads on who might be willing to make a decent 3/S damper for something in the $700 or less range? $5k is a wee bit steep.


Max

P.S. don't know about the pulley sizes for the Magna and Montero 6G72's, but I wouldn't bother with the Ross 6G72 dampers as they are simply remanned dampers. Might as well get (or try to find, I guess) the factory damper.

[mb7050]

my friend just purchased fluidamp for his evo for 270$ , I´m jealous.

if they are going to make fluiddampr for our cars it should be somewhere around 250-400$ (thats what they cost for most cars) I truly hope they do.

have anyone contacted ati ?

[mb7050]

I'z be rollin with the one I has.

Jeremy
oem damper ?

[bluemax_1]

my friend just purchased fluidamp for his evo for 270$ , I´m jealous.

if they are going to make fluiddampr for our cars it should be somewhere around 250-400$ (thats what they cost for most cars) I truly hope they do.

have anyone contacted ati ?

The difference in price is due to the fact that one of them is an existing platform, i.e. they're willing to set up the tooling to produce dampers in the proper dimensions knowing that they can continue to sell them for a decent timeframe as the platform is still being produced. With our damn cars, we're talking about a dead platform. No more of these cars are being produced, i.e. there is a limited number of potential owners who might buy these, = small production run = not worth their time to build one specifically to our dimensions = if we want them, they'll charge us an arm, a leg, and a testicle to take the time design and build a small run of units for the small number of folks who would bother, and the price WILL be high because they want to recoup their design and build time AND make a decent profit out of it from a (relatively) very small batch of product.

A couple of folks were talking to ATI about getting some made, but then one guy claimed he had started the talks with ATI about getting them made first, so the 2nd guy backed off saying, "OK, if this is your baby, I'll let you handle it" and then pfffttt... NOTHING came out of it. I don't give a SHIT who the hell gets credit for having them made, I JUST WANT THEM MADE.


Max

[hotGTO]

For the guys looking for the factory replacement, they are right here... Brand new dealer part for @ $200 from Cherry Hill Mitsubishi
https://www.partswebsite.com/cherryhilltriplex/?i=2&model=1590&make=141&year=1991&section=10&catid=10012&subcatid=20037&partid=62097&type=parts&image=E715040&imagecallout=35

[i3igpete]

Max unfortunately i don't have any contacts with aftermarket damper co's... I usually deal with OEM suppliers :(

[mb7050]

A couple of folks were talking to ATI about getting some made, but then one guy claimed he had started the talks with ATI about getting them made first, so the 2nd guy backed off saying, "OK, if this is your baby, I'll let you handle it" and then pfffttt... NOTHING came out of it. .





Max

thats ridiculous . I contacted ati yesterday will see what they say, hope the price is something less then an arm, a leg, and a testicle :) ...

[mb7050]

Just to let you know this is what I got from ati

"We have built custom dampers for that engine pricing cost starts off at 750.00"

"Just let me know I will send you out an invoice number and we will take a 250.00 engineering fee to get the ball rolling. The fee is non refundable and will be applied to the purchase of the damper. "



hmm. tempting need some time to think...

anyone know other companies that can make quality dampers ?

[GTwizard]

Don, as I mentioned before, it only needs to stay at the same RPM for ~.05 seconds for the harmonics to fully develop. Even during a 1st gear pull, a crank develops harmonics as the tach sweeps up, just as bad.

You are correct, But, Once an engine is loaded with drive trane resistence the chances of devistating hormonics begin to dwindle. I would never run a non dampener on a street car for sure. But for my race car I wish to have an under drive and getting a fluid damper in our configuration is close to nill. Been doing this 30 years and never lost a crank while racing. I also run a cast crank that is a lot more forgiving than what I would call a hard crank. Cast will flex rather than brake. I am also NA wich helped with the softer crank Choice. I have many times removed non-dampeners from customers cars as the risk is just to high and do not wish to risk them loosing a crank. I would never recomend a non-dampener to any one. But for me, and what I am doing with the car and the RPM range in wich I play. My biggest risk is under no load, between gears while shifting. But for me, and for now, I roll the dice. I have seen iceman_ii split 2 cranks and each time he was not running a damper and was not pushing the car at the time it broke. He now runs a dampener. LOL. I am more afraid of snapping a rod than bustin crank. Once I go 12.5 to 1s I may run a forged crank and will most likely build my own fluid damper with an under drive set up. This is a great thread as I have seen so many other say the damper have no place on our cars and that is just wrong. Just because I have lost my mind as have choicen to run with out, is no reason any one else should. In most all cases it is not a good idea to run with out a dampener.

[hotGTO]

I have a lightweight crank pully that was installed by a previous owner and I want to swap in a factory dampener, it's still 30k away from the next maintenance... Is it any easier to change it out if I'm not doing a whole service or am I stuck with all the same amount of labor just for the pulley?

[mb7050]

fisher consepts they dont make pulleys anymore ?

http://www.3si.org/forum/f25/custom-fisher-racing-pulley-195882/

http://www.3si.org/forum/f42/harmonic-dampener-revisited-175900/

[DrkZide]

Screw it, I'm keeping my Lightweight UDP











or drop in an LS1 :P

[mb7050]

Screw it, I'm keeping my Lightweight UDP


,until the bearing spins :D

I also contacted pitroadm will see what they offer...

[pos-vr4]

this
I Dont´t want oem pulley for my engine
I Don't want an underdrive pulley
I Don't want a pulley w/o a harmonic damper
I Don't care if the pulley is heavier or lighter.
I want superior damping for my engine !

I am not going to hit autobahn with the undampened pulley that I currently have.


to work properly it WILL have to be heavier, that is a good thing. this is the most cost effective option: http://www.bhjdynamics.com/

[Chris@Rvengeperformance]

lol this discussion will not die no matter what.

6 years and 2 cars later (162K one one , 155K on my tt, original engines in both) I'm still running a UDP and without worry.

They have a place for lowish power cars and you BPU guys can quit worrying.

[mb7050]

it depends I drive at autobahn every once in a while 150mph + constantly for hours.. my older 1995 3000gt spun bearing and that was shortly after i installed non dampned pulley not saying it caused it but....

[Chris@Rvengeperformance]

lol not going to argue with you, I'm sure driving 150 MPH constantly had nothing to do with engine failure on a 10+ year old car.

[DrkZide]

What about a TT LS1? Drop that sucker on a Corvette drive train and you're gold. No more insufficient aftermarket woes

[mb7050]

lol not going to argue with you, I'm sure driving 150 MPH constantly had nothing to do with engine failure on a 10+ year old car.

no need to argue about anything . actually that car was 9 years old back then and 70k miles on the clock (2004) not that it matters anyway I´m still not saying UDP pulley caused it . :)

[hotGTO]

Why would a manufacturer waste the money and sacrifice the hp on a part like that if it made zero difference. There is no explanation except that it is needed to serve it's purpose. Why would they still be using them in new motors today if they are not needed?

[Chris@Rvengeperformance]

who said they make no difference?

To me personally, for the power output I'm shooting for, the risk of the stock pulley seperating outweighs any risk of an UDP causing an issue. I've seen plenty of engines wiped out by the stock pulley seperating and so far no concrete failures caused by a solid pulley.

If you want to replace the stock pulley every 5 years or so then go right ahead, meanwhile I'll be thousands of miles down the road still running my original solid like I have been forever.

Just don't pretend like your engine is going to magically going to fall apart using a part that has been proven to work for over a decade and scare all of these guys with UDPs to run to the nearest mechanic to get them replaced. Some of the biggest names in our market have used them extremely successfully for YEARS.

[mb7050]

this
I Dont´t want oem pulley for my engine
I Don't want an underdrive pulley
I Don't want a pulley w/o a harmonic damper
I Don't care if the pulley is heavier or lighter.
I want superior damping for my engine !

I am not going to hit autobahn with the undampened pulley that I currently have.

[Hammer]

well, thats to say if the 6g72 had a better option we could. as it is the OE damper only neutralizes a very small range anyway, and after a change of internals its range of operation is even smaller.

What do you know about the "modified" Evo engine?? was it rebalanced after the internals were changed?

I can add in aircraft harmonic dampners are considered too heavy and not used. What they do instead is placard a warning "Do not operate this engine in this range usually like 1,800-1,900 RPM for any length of time." That would be identified as the specific range where damage can be done to the engine. Now it is possible that some of the people that never have had a problem using underdrive light weight pullys have just by luck managed to stay outside of the danger zone for our engine. It would be nice to know what RPM range is considered dangerous to operate in. Of course like has already been said it will be different if you change out some of the rotating parts. But for the stock engine with stock parts we should be able to find out the dangerous RPM zone of operation. Because most engines use these and in auto world are considered needed then I would guess the dnagerous RPM zone is probably one that we use quite frequently. Maybe like cruising at 65 MPH in high gear on the highway. Just guessing out loud.

[J. Fast]

No one is denying the fact that all multicylinder cars experience low torque vibration and high torque vibration (one at low RPM and one at high RPM). Quite plainly you can almost hear the difference in the engine putt's when you approach harmonic problem areas. If you want to conduct a little test you can drive towards a 2% grade hill and approach it doing 50mph in the highest gear (5th or 6th depending on your model). Without changing gears floor it about 100ft into the climb. There will be a specific speed and rpm range where your car starts to resonate sound and vibrate. It will start to vibrate the rearview mirror like crazy and will even change the tone of the exhaust and maybe make a few things rattle. Well, if you hear that sound... that's what your dampener is designed for absorbing. If you drive your car like that without switching gears... you need a harmonic dampener (and a driving lesson). I personally drive my vehicle in the heart of my gears and don't go storming up steep grades doing 65mph in 6th gear or 65mph in 2nd gear. Again, roll thru the gears.

Jeremy

[DrkZide]

I have solid motor mounts so that vibration is pretty apparent. It was the same when I had the stock dampener vs the UDP. I also get that vibration in first when I start driving the car.

[i3igpete]

Without changing gears floor it about 100ft into the climb. There will be a specific speed and rpm range where your car starts to resonate sound and vibrate. It will start to vibrate the rearview mirror like crazy and will even change the tone of the exhaust and maybe make a few things rattle. Well, if you hear that sound... that's what your dampener is designed for absorbing

Incorrect, that low rpm vibration is NOT crankshaft torsionals. It's the natural frequency of your engine/transmission and the mounting system. This is tuned separately and the paper in the OP mentions it briefly on page 6. These are typically in the frequency region if you can feel a rumbling sensation - you can't feel vibration of the crank twisting because it is too high of a frequency.

I also deal with engine mount dynamics in my work. Here is a typical analysis of mounting system natural vibration.

http://i129.photobucket.com/albums/p239/i3igpete/private/mountfreq.png

[J. Fast]

I'm assuming those are graphs of 360 degree crank rototations (60 degree each maybe)?


i3igpete

...low rpm vibration is NOT crankshaft torsionals. It's the natural frequency of your engine/transmission and the mounting system.

Out of curiosity, how many natural frequencies are there in an engine?

Jeremy

[i3igpete]

if you recall from vibration analysis, mode shapes are unitless. all they have is frequency (listed at the top of each mode shape as i've presented) and direction (X,Y,Z,Xrot,Yrot,Zrot). the rotational speed of the crankshaft doesn't factor into the natural frequency, only the force-response.

[hotGTO]

@i3igpete:

Are you saying the low RPM frequency, ie: accelerating from a low speed in 4th gear instead of downshifting to 3rd causing a low resonating vibration, is not bad for the engine in the way the high RPM vibrations are?

[i3igpete]

yes, they are two different things. one is your engine mounts getting beat up, the other is your crankshaft twisting.

[bluemax_1]

@i3igpete:

Are you saying the low RPM frequency, ie: accelerating from a low speed in 4th gear instead of downshifting to 3rd causing a low resonating vibration, is not bad for the engine in the way the high RPM vibrations are?


yes, they are two different things. one is your engine mounts getting beat up, the other is your crankshaft twisting.
I just thought I'd clarify this for any noobs reading who might get the wrong impression:

What Pete is saying is that they are 2 different things, the crankshaft's resonant frequency causing the twisting of the crankshaft that can't really be felt by the occupants of the vehicle (rubber mounts are great at attenuating higher frequencies) vs. the engine assembly hitting a resonant frequency that makes the whole assembly vibrate, which can be felt in the car.

That said though, lugging the engine in a gear that's too low can be a different kind of bad for the engine. Doing this can trigger detonation (low rpm, high load) which can be all kinds of bad, but a different bad from what the harmonic damper protects the engine from.


Max

[hotGTO]

I just thought I'd clarify this for any noobs reading who might get the wrong impression:

What Pete is saying is that they are 2 different things, the crankshaft's resonant frequency causing the twisting of the crankshaft that can't really be felt by the occupants of the vehicle (rubber mounts are great at attenuating higher frequencies) vs. the engine assembly hitting a resonant frequency that makes the whole assembly vibrate, which can be felt in the car.

That said though, lugging the engine in a gear that's too low can be a different kind of bad for the engine. Doing this can trigger detonation (low rpm, high load) which can be all kinds of bad, but a different bad from what the harmonic damper protects the engine from.


Max

I didn't figure either was good, but it's good to know the difference between what "vibration" is causing a specific kind of damage and how it relates to your driving habits and/or maintenance routines and/or parts choices... so any time you guys who are "in the know" can translate it to us admitted hobbyists, it helps us know the science behind what we are talking about, and what we see hear and feel when we drive, and helps us make informed choices. So Thanks!

[mb7050]

So what do you think of this damper ?
I have heard nothing but good things about these dampers in racing applications in fact they're proven on some of the fastest Aussie cars around perhaps fastest GTR's/RB's and 1fz´s, 2jz´s anywhere in the world !
some people prefer this over ati .
http://img10.imageshack.us/img10/8407/dsc0181sd.jpg



METAL JACKET Harmonic Balancers / Crank Pulley Dampers

A World First In Balancer / Damper Design !! Encased Dampener Within Balancers

Introducing a revolutionary development in torsional dampening technology. Utilising the ROSS Tuffbond original elastrometric bonding process to produce the ROSS Metaljacket® series harmonic balancers / crank pulley dampers.

Metaljacket Harmonic Balancers/Crank Dampers designed and manufactured by ROSS.

Metaljacket use the highest spec. 6000 series alloys along with aerospace 7075 hard anodised crankshaft hubs.

Metaljacket is designed to be used on race machines that are driven by enthusiasts on the street, strip,circuit or on the water.

The accessary drive pulley ratios are standard unless requested.

These are the worlds best used by world champions.

* 360 timing marks at 1° intervals
* Adjustable timing disc, for TDC accuracy
* Precision CNC machined 40 Tonne tensile alloy steel hub and vibration dampening ring
* Dampening ring and hub permanently bonded together on TWO axis by our exclusive Tuffbond elastrometric bonding process, ensuring maximum harmful vibrations are absorbed.
* balancer is anodized for durability and appearance
* Absorbs more damaging torsional harmonic vibrations
* Quicker engine acceleration
* Increases engine life
* Lifetime warranty, even for racing use - a world first!
* Never requires maintenance or rebuilding - ever!
* Rated to 1500 HP
* Encapsulated MetaL Jacket® design exceeds AN DRA and SF1 i8.1(USA) requirements
* Fits standard or modified engines
* Affordably priced

So

"We can make a batch of dampeners to suit the 6G72.

We would need a sample.



Your price for 1 6G72 metal jacket dampener would be $614.25aud +
tooling & freight
x 2 dampener $583.53aud per dampener + tooling & freight
x 3 dampener $552.82aud per dampener + tooling & freight
x 4 dampener $522.22aud per dampener + tooling & freight
x 5 dampener $491.40aud per dampener + tooling & freight"


so it would be 484.5 USD if 5 or more people would buy but remember shipping from Australia might be pretty pricey ... not a bad price at all remember this damper costs up to 600 USD for most applications !

I actually prefer this damper over ATI mainly because it doesnt need maintenance or rebuilding - ever and lifetime warranty ...

[mb7050]

http://www.youtube.com/watch?v=2M7HPUKiPO8

[hotGTO]

It's beyond me how anyone could throw 10-20 grand into building a 600+ horsepower 3s but skimp on the damper and not be willing to pay a few hundred to help protect the investment. As soon as I get anywhere near 500 hp (maybe another year) I will be in looking for one, but I will have to make do with oem until I can afford that.

[bluemax_1]

mb7050,

that's a pretty decent price for an aftermarket damper. It appears that it's an elastomeric damper that is non-tunable though. One of the things about the ATI dampers is that they build them to general specs and builders can then have the damper dyno tuned specifically for THEIR engine (if they choose to). To dyno tune them, they make pulls on the dyno with equipment measuring the vibration frequencies and they then change the elastomer rings between different compounds (and they might be able to change the mass of the inertia ring too).


Max

[mb7050]

Fluidampr and most of the dampers from Japan for 6g72 are non-tunable + they cost up to 2k.

I was thinking that Fluidampr is the best IMO. there is no best between these dampers until actual testing is done ...
Fluidampr can go bad its not that superior as advertised, Silicon does have a life span. And unfortunately It doesn't have a way to check the fluid to ensure it isn't going bad so you never know !
http://www.metaldyne.com/metaldyne/sections/engine/prod_SP_silicone_testing.aspx
http://130.15.85.212/proceedings/proceedings_WorldCongress/WorldCongress07/articles/sessions/papers/A746.pdf


kinda unbiased test but ...
ATI vs Fluidampr
http://www.fluidampr.com/FACTS.htm

when they make a custom damper they need to know at least

they need the oem damper
the snout of the crank in three different parts
stroke of crank
weight of crank
weight of flywheel
max rpm
max power

more values , better outcome.

http://www.atiracing.com/pdf/custom-damper-form.pdf

it should be pretty good right out of the box.

http://www.atiracing.com/products/dampers/testing/index.htm
yeah but VERY expensive and i think in most cases unnecessary.

[mb7050]

It's beyond me how anyone could throw 10-20 grand into building a 600+ horsepower 3s but skimp on the damper and not be willing to pay a few hundred to help protect the investment. As soon as I get anywhere near 500 hp (maybe another year) I will be in looking for one, but I will have to make do with oem until I can afford that.

Its beyond me too . I think its ofter "overlooked" hell its just a crank pulley some say but poeple spend huge amount of $$$$$ on exhausts, intake manifolds, intakes, etc. and none of them are nearly as important as something like a crank damper. Crank damper not only could help gain some HP but also protect your engine the BEST it can.

[bluemax_1]

The Fluidampr link (granted, it IS a manufacturer site and therefore potentially biased) appears to confirm what Pete's paper indicates, that a viscous damper attenuates better at a wider range of frequencies.

I don't know about other manufacturers, but ATI dampers ARE tunable, and the tuning is done in a similar manner to how the Fluidampr testing was done. They do a dyno pull with the equipment taking measurements, figure out which order harmonics are potentially the most damaging, then they use elastomers of different durometer to dampen those frequencies specifically in the engine that the damper is mounted on.

Pete can correct me on this, but IIRC, that is how ALL OEM elastomeric dampers are tuned. They have the spec engine (which all production engines will be built to, using the same parts etc.), which they run on a dyno with a basic damper and measure the harmonics to see where the most destructive vibrations are, tune the damper to attenuate the worst harmonics and then all the engines which are built identically, are fitted with the tuned dampers which are also built identically.

Unfortunately (for us), changes in components seem to affect the vibrations. The specs requested by Ross, seem to be general enough to be related mostly to fitment and general size of the inertial mass for the given engine. The specs are not specific enough to fine tune the damper. Different crankshafts (nitrided vs not), OEM rods and pistons vs forged aftermarket etc. These all appear to make a tangible difference.

With the ATI unit, you have a 'ballpark' damper. It's built to attenuate in the general ballpark of the engine's harmonics. If you choose to, (and folks looking for max longevity esp. at high hp would be ideal candidates) you can have the damper tuned specifically to attenuate YOUR engine's worst harmonics.

With the Fluidampr unit, because it's a viscous type damper, it attenuates all frequencies better than an elastomeric damper, so aside from deciding on how much inertial mass we can get away with based on dimensional constraints, there is no further tuning of the damper required.

With the Ross damper (which appears to be elastomeric), it appears we would get a ballpark damper that is non-tunable. In addition, I'm curious about their 'lifetime warranty'. A harmonic balancer/damper works by converting the vibrations to heat within the elastomer or the viscous media. As a result, the medium of conversion tends to degrade over time (like our damn harmonic balancers rubber rings deteriorating and allowing the external inertia ring to separate and fly off god knows where). With ATI, the elastomers are basically oversized rubber O-rings that mount internally to the damper and can be tuned via swapping the rubber rings for a different durometer. The ATI damper can also be rebuilt/refreshed after X amount of mileage by replacing these rubber O-rings.

Rubber will degrade over time just from exposure to air, humidity, oils, chemicals, sunlight, heat and cold etc. The rubber in a harmonic balancer will wear out faster from usage. For example, if you bought 2 OEM dampers and mounted one on your car and left the other sitting on a shelf, the one on the car would wear out faster not just due to exposure to the elements, but because in the very act of doing its job, it is being heat cycled. Makes me wonder how they can offer a lifetime warranty on the Ross dampers, unless they simply mean "when the rubber breaks down, we'll rebuild it for free".


Max

[mb7050]

I would too like to know more about this : Introducing a revolutionary development in torsional dampening technology. Utilising the ROSS Tuffbond original elastrometric bonding process .

If you want to know more about the lifetime warranty you could of course just ask them ;).


http://www.gtr.co.uk/forum/132765-ati-street-crank-damper-2.html

http://www.supraforums.com.au/forum/archive/index.php?t-59701.html

[i3igpete]

Pete can correct me on this, but IIRC, that is how ALL OEM elastomeric dampers are tuned. They have the spec engine (which all production engines will be built to, using the same parts etc.), which they run on a dyno with a basic damper and measure the harmonics to see where the most destructive vibrations are, tune the damper to attenuate the worst harmonics and then all the engines which are built identically, are fitted with the tuned dampers which are also built identically.


yup. the stiffness of crankshafts aren't generally changable unless you have a massive undercutting for the journals or pins.

you can affect the inertia of the crank by massively knife-edging the crank or using titanium rods, but in general, removal of mass for balance purposes or switching to a different brand of steel rods generally doesn't affect the natural frequency of the crank assembly all that much.

[mb7050]

I am intrested to buy one ROSS damper for 484.5 $ since the ati will cost me up to 1000 $ + it needs rebuilding every once in a while but where could I find 4 more people to buy this damper any ideas ?

[hotGTO]

I am intrested to buy one ROSS damper for 484.5 $ since the ati will cost me up to 1000 $ + it needs rebuilding every once in a while but where could I find 4 more people to buy this damper any ideas ?

Not till beginning of next year sometime after my raise...

[VR-4 0wnz j00]

I just got a 3SX lightweight pulley to replace my great condition OEM pulley. Well see how it goes.

[mb7050]

3SX lightweight pulley

I use it as a nice book weight, works wonders

[mb7050]

Nelson had ATI make some Super Dampers for his engines. Of course that's hardly an affordable solution.

I´m fairly certain Nelson bought his damper from A.J Berge when he switched to a V8 class and sold all of his stuff to Nelson).


is designed to compete with the top cars of the category. that means 6.5-sec ET's and 210+ mph.http://www.urbanracer.com/gallery/articles/sema/2004/lv/0055.jpg
http://www.urbanracer.com/gallery/articles/sema/2004/lv/0057.jpg
http://img64.imageshack.us/img64/1894/84004145.jpg
http://img402.imageshack.us/img402/8135/37237126.jpg
http://img687.imageshack.us/img687/69/94469679.jpg
http://img507.imageshack.us/img507/3674/62845754.jpg

[CoopKill]

I am intrested to buy one ROSS damper for 484.5 $ since the ati will cost me up to 1000 $ + it needs rebuilding every once in a while but where could I find 4 more people to buy this damper any ideas ?

Possible in a few months when ready... (other craps on the list before this)

[green-lantern]

http://img507.imageshack.us/img507/3674/62845754.jpg

WOW! giggity giggity fap fap fap!


I am interested in a good dampener. I've never been a fan of the stock one after it falling apart on me so I'm still running a 3sx one.