Abdullah

i will get a 398 LT1 stroker kit ( 0.040" pistons) for my Z from combination motorsports and i 'm willing to use an aftermarket dampner just to be on the safe side. now, from what i know the fluidDamper dampner will work better than ATI from Idle to 7000 rpm above that ATI is better, also as i was told that ATI will not work except from 4000 rpm and up where fluiddamper will work from idle and up. so i 'm leaning toward the fluiddamper. since the custom cam from Nutek for this 398 LT1 kit has 237/244 @ 0.050" 112lsa 108 CL .582"/.592" with 1.6 rockers and it might not go over 7000 rpm since it is a stroker not a 355 or 350 i mean stock stroke, isn't that right? so what Experts would recommend? thanks.

Injuneer

You're going to get two groups of people answering this.... one that loves Fluidampr, and one that hates them. Seems to be no middle ground. The shop that built my engine doesn't like the Fluidampr and recommends the ATI - that's what I run. I know George Baxter and Madman both used the ATI on their LT1's. But then I see Warren Johnson endorsing Fluidampr.... so it appears to be a matter of flipping a coin.

There are vibration displacement vs. rpm curves on the Fluidampr website, comparing it with the ATI.... I don't think it clearly indicates what is stated in your post above.

Fluidampr Tech

ATI Tech

quicksilver97ta

FWIW, the LT4 dampner is a dual mass unit for higher rpms. Also FWIW, jegs now offers an SFI apprv'd dampner. Both options are cheaper than Fluidampner. I wish Fluidampner would offer an LT1 Street dampner.

badass383

Fluid damper offers anything you want for the street. I own one from Jegs. I wish I got the ATI. I just learned something you won't find out any where else. The Fluid damper uses super thick silicon and it takes several minutes to warm up.

What does this mean? Well if you want to put it on your daily driver, plan on 5 minute warm ups before you go anywhere. If you don't on cool or cold days, you gona shake your teeth out. Not very good for the mains. My car is not a daily driver so I guess I'll be ok.

Food for thought.

Injuneer

I know they make a "Fluidampr" for the LT1, but they do not show a "Streetdampr" for the LT1, at least they do not list one on their website.

As far as the warm-up, here's Fluidampr's take on that:

badass383

I guess I would put out the propaganda if I made something like that too but my brother in law has one on his 68 Camaro and I have one also and he lives in up state NY. His dental bills are higher than mine in VA. LOL

Don't waste your money.

Injuneer

Its entriely possible to produce a visco-elastic fluid that has the property of maintaining a uniform viscosity over an extremely wide range of temperatures.... its even possible to produce one that has an inverse viscosity, rising with temperature.... that's what they used in the "viscous drive" engine cooling fans 40 years ago.... .

Mindgame

I agree, it's a coin flip. You'll see just as many guys using ATI as you will Fluidamper. WJ is a good example and I can guarantee he wouldn't use one without doing a ton of testing first.

The complaints I've heard one way or the other are usually based on broken crank snouts but I've seen alot of broken crank-snout motors that had signs of other problems when torn down. One in particular (judging by a mic reading of the snout diameter), had the incorrect press fit tolerance for the dampener. So you have to wonder how much of that goes on and whether or not people are really adhering to the manufacturer's specs. Lots of variables and lots of blame when something goes wrong.
Each are excellent dampeners in my opinion..... same with BHJ, althought I don't believe they make an LT unit yet.

-Mindgame

WMcD

Is a Fllluidamper or ATI worth the cost? I run my 350 LT1 to 6500 almost every weekend at the track with the stock damper. For a stock displacement with stock crank, rods and pistons do you feel the cost of an aftermarket damper is justified by either being good insurance or hp increase if any.

Abdullah

so Mindgame, what is the press fit tolarance for the LT1 fluiddamper dampner? how about the ATI one?

what is the diameter of the snout of the LT1 stock crank? how about others like eagle 3.875" forged 4340 crank which i'm using in the 398 kit? what about Callies racemaster 3.875" crank? well, looks like these cranks have thier specific snout regardless of the stroke. thanks.

quicksilver97ta

I wonder who manufactures the new Jegs brand or if they actually make it themselves.

Mindgame

Fluidampr, .0005-.0015 press fit. Don't remember on ATI.... should be real close to the same.

Of course we're talking in general here, as I was mentioning problems I've seen that were blamed on the dampener...... not necessarily LT1 specific.
On LTs you have the hub, on older small blocks, the crank snout and obviously that tolerance should be right on but you'd have to check to make sure. Stuff sometimes gets by QC.

-Mindgame

arnie

Fluidamper specs call out 1.245-1.246" dia.

what is the diameter of the snout of the LT1 stock crank? how about others like eagle 3.875" forged 4340 crank which i'm using in the 398 kit?.....

You can figure on the oem snout to be just a bit more press than a keyed eagle. Figure on 1.246" for the eagle (don't know what their tolerance is) and about 1.2466-7". (again, unaware of the range) for oem LT1. HTH.

carnutz

the machine shop i use doesn't like the fluid damper cuz they say they are "heavy". The ATI is lighter, less weight to spin. just like putting a aluminum drive shaft in less mass the quicker it spinns up. They of course ballance everything, but they like the ATI better, lighter rotating assy........ you figgre it out.

arnie

Interesting comment. Ask the guy at the machine shop what the weight/size (mass) is of a high rpm HD gm dampner compared to one for a 'grocery getter'. Let him figure it out.