fuild dampner vs ati dampner

C

chance cobb

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May 28, 2010
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well like the title states who uses which one and and thing bad to say about the other? An engine builder told me today that a fuild dampener will destroy a crank. He was all one sided for ati . Is this guy on crack or does he know something?
 
there are a couple crank manufacturers out there that wont warranttee a crank if it has seen a fluid dampner
there is a ton of debate out there on the internet about the pros and cons of various crank dampner types
 
Some reading for you........

First post is from ATI.
Hello,

Innovators West damper is not viscous, like you are thinking. That damper has Clutches and some sort of clutch fluild inside of it. But not a silicone fluild. I have only ever had one here at ATI and it was for a racer, with an I-6 Jeep motor, who was having the spacing set up the same for one of our dampers since he was not getting the results he wanted with theirs. Namely timing belts breaking every weekend.

Over the past 15+ years there has been only one company that has had no trouble, no recalls, no design changes, and no bankrupcy problems, that is ATI. Fisher, Innovators West, TCI, and Fluidampr all have done atleat one of those things. That should tell you someting about our product and how it works.

Not all diesel engines come with viscous dampers anymore. Cummins for example has atleast 2 dampers that are elastomer. As people are tuning up their duelles and work trucks, the need for better dampers has happened. That is why I have the Cummins dampers here.

Also in the tractor pulling world, the engine builders are looking to ATI to fit them with a damper that works. Southern Illinois Crankshaft is a good example. Mike builds some very large, very awesome motors. How about a 230lbs crankshaft that starts life as billet, for a 600Ci inline 6? We make an 8in damper for him with an oversized inertia weight. He has bought 20 in the last 2 years for his engines.

I will not tell you that Silicone filled dampers do not work. But I do know for a fact that when you get above a "stock" RPM, they stop doing their job. 5,500 to 5,800 is it for fluid. I have no problem telling people who stay at or below those RPM's to use a Stock damper or silicone filled damper.

Example, GM's 572 Crate Motors. The peak RPM on those engines is 6,000 for the little motor and 6,800 for the big one. Look at the damper on those engines, 8 in standard damper from ATI's shelf with a white face decal. Not a fluid damper for those "low" rpm engines.

Last thing to think about. Why does Fluidampr not have a 2 piece damper and hub setup like ATI's. Answer, they can not get the bolts to stay in the damper and hold it together. Why? Because the damper does not function above 5,800 rpm. Bolts backing out is a common sign of harmonics.

JCBJr

jcbuncc


Second post......
Heavier will always do a better job at dampening harmonics than light. Harmonic energy is diffused into the damper and mass plays a part. Light will accelerate quicker than heavy, so there is a trade-off point.

I've participated in some damper torsional testing and have also been present during tests conducted by a retired engineer from an OEM supplier who at that time was working as a freelance consultant.

One general conclusion from both sessions and many parts/designs tested is the elastometer damper performs best in an automotive engine that is sweeping upward in RPM over a broad range. Usually there are 3 resonant peaks during the sweep and the rubber band dampers do the best job in this situation.

Other non-elastometer designs didn't repeat (viscous fluid-temperature sensitivity) or flat did not work (friction-clutches and ball bearings). In one case the damper (single band elastometer) blew itself apart because that vendor shipped a part that was too light to do it's job.

Having said all of that, I will recommend ATI because their parts are completely serviceable and more easily tuned for a specific application. You can call them directly and let them know what all of your parts weigh plus your intended range of operation for the engine to see whether you need something different than their off the shelf part. Chances are the one on the shelf at the speed shop would work just fine though.

Worth mentioning, both test sessions evaluated Romac dampers. ATI was deemed to be the better of the two but in one test on a particular engine configuration the Romac was better than ATI below ~5000 RPM.

Third ..........from GUY TRIPP........
8,000+ rpm circle track gassers.
I used to build Competitive racing engines on the West Coast. Nascar Winston West, Southwest Tour, Late Model etc. And some drag stuff.

I had a customer with one of my engines fail about 5 races into the season. The initial inspection revealed what appeared to be a broken rod bolt. The rod bearings looked good, but the mains were terrible. Interesting as these were Carrillo rods with Carr rod bolts. The rod bolts were $300.00 a set at the time and were considered indestructible.

We built a new motor and transfered all of his accessories over from the old one. Clutch, dry sump pump, dampener, pulleys, carb, dist etc. While running it on the dyno we noticed it was down about 20 hp from where it should be.

Checking the filters revealed some bearing material. We tore it down and confirmed our suspicions:

#1 main perfect except for one little shiny area
#2 main worn into the copper
#3 main perfect except for one little shiny area
#4 main worn into the copper
#5 main perfect except for one little shiny area

All the rod bearings had that little shiny area in them just like the mains.

We checked rechecked and checked everything again. It all checked out without any explanation as to what was causing the worn bearings. I called one of my friends who worked in the engine shop at one of the top teams in Winston Cup and asked for his opinion. He said it sounded like some sort of harmonic was going through the motor and causing the problem. He asked about the balance job as we used to over balance the cranks back then by approx. 2%. Same as Cup.

He then asked if I we were running a Fluidampener by any chance. Then went on to explain all the trouble they had in Cup with them.

I took the crank over to the balance machine as we did our balancing in house and verified the balance. Then bolted on the flywheel and verified balance, then bolted on the Fluidampener and again verified balance. Everything checked out. I figured that if the viscous fluid had hardened I would see an out of balance condition.

I called Fluidampener and asked if I could send it back to have it analyzed. The said sure and that they would replace it free of charge. I asked if I would be provided with a copy of the lab report. The said no, they would replace the part and that was it.

This bothered me as I was looking for answers not just replacement parts. As an engine builder I need a way to qualify new and used parts (during rebuild) before I install them into a $20,000- $35,000 motor.

I reassembled the engine and this time used an ATI dampner. The engine ran perfect and my 20 hp was back. I ran it through some extensive endurance cycles which brought the boss out of his office wanting to know if I was actually trying to break it this time. I responded "Yes". "Better to break it here than out on the race track." It took the abuse without any problems.

Next I dropped the pan on the dyno and inspected all the bearings. Everything was perfect.

Only one thing left to do. Re-install the Fluidampener and see if it causes a problem. This caused the boss to leave for the rest of the day mumbling something about getting a couple of drinks on the way home and how I was out of my mind.

I ran two really quick easy tests to 7,000 rpm and everything looked good. A little down on power but no bearing material in the filters. I then ran two quick tests to 7,500 and checked the filters and low and behold, bearing material. A quick drop of the dry sump pan to inspect the bearings revealed the same pattern we had seen before with every other main bearing wearing out. Obviously some harmonic frequencies were causing the crankshaft to move around like a limp noodle, and eventually caused the rod bolt to break in the first motor.

End Test.

Interesting to note that the Fluidampener was fine for about five 200 lap races and probably an equal amount of practice. Yet without a way to inspect or determine what went wrong or even distinguish between a good one or a bad one how can we continue to use this company's product?

Next, we had a customer that had a perfectly fine running engine decide to install a Fluidampener because his buddies read it was supposed to be the next greatest thing to sliced bread. He brought the thing in with a hole in the side of it, madder than a Hornet. We pulled his work order and showed him where we had installed an ATI and now the motor had a Fluidampener. We then predicted what the motor would look like inside and proceeded to disassemble it in front of him. He wrote a big check and walked out mumbling something about suing Fluidampener.

Over the years I have had many a racer call me looking for answers to his main bearing problems or broken crank problems that cropped up seemingly out of the blue, and in 99% of the cases a Fluidampner was to blame.

You guys do what you want. I'm just offering my experiences. Whether you use my advice or buy into the marketing hype printed on somebody's web site is up to you.

As for me, if it ain't broke don't fix it. Until ATI comes up with a Dmax unit, I'll run stock thank you.
 
I have run both in the last 25 years of engine development and both do their job. There is always several ways to get to the same conclusions. I have run well over 10,000 rpms on my competition eliminator engines and the Odd fire Chevy Splayed V6 and it is a rattle trap . Both balancers held up with little or no wear on the crank or bearings. We inspected the engines every 30 to 40 runs.
There are people that will argue to the death either way , but the fact is many Pro NASCAR teams run both as well.
I ran a ATI on the engine I did for the DR Performance truck and you could hear the difference in the ringing from the gear train.
I currently run Fluidamper on my Duramax engines. I have seen them hold up as well
 
Been running a fluidamper for years. After beating on this engine for over a year 1000hp+ 2400ftlbs+ the bearings look like new. Have no idea why I'd change it out.

C13C1958-43C1-48DC-A2ED-6D0C13541039-612-0000021DDA0AE0BE.jpg
 
Joesixpack said:
Been running a fluidamper for years. After beating on this engine for over a year 1000hp+ 2400ftlbs+ the bearings look like new. Have no idea why I'd change it out.

C13C1958-43C1-48DC-A2ED-6D0C13541039-612-0000021DDA0AE0BE.jpg
Click to expand...

Joe a little coating on those bearings with give you a little safety measure.
Polydyn has extra clearance coating bearings in stock for the Cummins for a competitive price with non-coated bearings
 
here is the fluidamper on my Dmax program

IMAG1179.jpg



when I built this cummins I used a ATI .


100_0014-2.jpg
 
im curious about the Cummins marine part number damnper vs the stock. Not knowing what the "marine viscous" dampner is built to, but is it safer to run the the marine viscous in a automotive application above stock rpm?
 
not to mention there was a scattered run of CR common rail engines that had rod failures due to rod bolts. but seemed to be isloated to a certain year(s), both automotive and industrial.
 
I think not.............

COMP461 said:

There are people that will argue to the death either way , but the fact is many Pro NASCAR teams run both as well.
Click to expand...

I would like to see one team in Nascar/Cup that uses a Fluidampner. I have done tech work for alot of races and I have NEVER seen one.

When NASCAR lines up a 40+ car fi eld to start a 500 mile race, at
Atlanta for instance, each car will record about 3.3 million cycles
on the engine. That’s a total of 132 million engine cycles for the
hours of practice and competition for 40 cars. For comparison,
if you have ever watched the in-car monitors on TV, each car
comes off the corners at about 5000 to 5500 RPM. They then
accelerate down the straight away to 9500 - 9800 RPM and lift for
Turn One, exit at Turn Two and then do the same thing down the
back stretch. That’s the equivalent of 2 extremely hard 1/4 mile
runs per lap. Multiply that by 500 laps or 1000 1/4 mile passes
x 40 cars = 40,000 1/4 mile passes in 3 hours. Breakage is
usually confi ned to a valve spring, valve or rocker arm. Crankshaft
breakage is extremely rare.
Every engine is equipped with an
ATI Super Damper
. That’s correct; it’s the only damper that you
will fi nd in this or any other NASCAR race.
Direct quote from ATI literature.

Now saying that, under about 7k rpm Fluidampner CAN be better sometimes, but SCAT cranks, for instance, specifically says DO NOT use a Fluidampner with their CAST cranks.
 
Last edited:
by Matty169s description of bearings - and having looked at five sets in three motors, all with the same little shiney spots - one might begin to wonder.
We have never hit the copper - but we do get wierd shiney spots - in areas that would not be what I call load related, and it is consistantly the same areas - especially on the rods
now we never see over 5100 rpm but do run a Fluid damper
Maybe there is an ATI in my future
who sells them and how much?
or anyone got a used one layin around i could buy to try
interesting
 
Every engine is equipped with an
ATI Super Damper
. That’s correct; it’s the only damper that you
will fi nd in this or any other NASCAR race.
Click to expand...

Thats easy and does NOT relate to a better product at all.....Its called SPONSORSHIP!

Fluidampr has no reason to give away their parts to people who already have enough money to buy their own.Thats a HUGE check to stroke if you want your decal on the side of ANY Cup series.NASCAR mandates what parts you use and what decals get placed on the car and where.

Fluidampr hands down is the better product.
 
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