ATI vs Fluidampr
 

So as I am piecing together my long block I have come to the damper decision point --

I see a lot of people seem to use the ATI, have heard some give and take about the supermiata unit (seems fixed weight, idk about that), and have also heard good things about the fluidampr however mostly from outside of the miata world

build includes rods, pistons, bearings, and a boundary oil pump;

from what I have gathered, having BE and a damper is generally overkill for the 350whp I would like, which is just my style - I like bulletproof and smooth,
and from what I see, people like the ATI because it is press fit rather than the fluidampr still using the 4 bolts (is this correct?)

I personally am leaning towards fluidampr because it is about 120 less expensive and seems a little easier to install/uninstall and will still add a degree of protection over stock, particularly when coupled with the BE pump

100% street car

Am I wrong? I'm not terribly concerned with pressing something on if necessary and it is really that much better of a product (though I have heard the fluidampr is actually a more finished looking with things laser engraved rather than stickered on), I do however like the simplicity of the bolts and the cheaper price. I would like to save a little money where I can on this build, and this seemed like a middle-of-the-road solution -- Thoughts?

I'm running the ATI and boundary with less then 300hp. It is more for reliability. Rumor has it that the fluiddamper had longevity issues because of the orings leaking.

There have been complaints that it is difficult to install the ATI because of the attached gear but that is only because of not knowing the proper procedure. It is no more difficult to install and has been a good product for me.

Interesting what Leo stated about fluidampr's leaking internally. I went with fluidampr on my car for one big reason, you don't have to press them on and off. I've seen some ATI dampers get seriously stuck on the crank with the interference fit, and I didn't want to have to mess with that, particularly because the motor was already in my car.

Other selling points for the fluidampr for me were that they don't need rebuilds, and I can install it without re-timing the car (small plus, but it did make the install quicker and easier, particularly when I had to pull it off again shortly after installing to change a failed trigger wheel).

Also understanding how a damper such as a fluidamer works, compared to an elastomer design. A fluidampr "should" balance at varying RPMS and frequencies better, where as the ATIs elastomer design is (similarly to a stock damper) tuned for certain RPMs and scenarios. Also in my research I saw some comparisons in vibration dampening between the two, and it appeared that fluidamper was as good, or even superior, to the ATI in sub 7,000 RPM applications, where after 7k rpm the ATI was clearly superior.

In my mind on a BP motor that only revs to 7200 at the most, this would be just as good or better than the ATI. Particularly for a car on the track spending most of its time between 5-7k rpm.
https://cimg6.ibsrv.net/gimg/www.mia...71fb61bb8.jpeg

But for me, it was mostly a convenience thing, and I'm sure both of these dampers, as well as the supermiata one, are vastly superior to the OEM one, especially a worn out 100+k miles one. I in no way am saying fluidamper is actually better than the ATI or others, because I have no idea, these are just the factors that swayed me in my recent purchase decision.

This is not actually correct. I thought the same when I bought my fluidampr, and when I got it I was surprised to see that I did have to remove the crank bolt to install it. The newer fluidampr revision does in fact have a key-way for the crank, is held on by the main crank bolt and not the 4 tiny weak-ass bolts that hold on the stock unit. It slides on after the stock timing belt cog, and is sandwiched on with the main crank bolt. It's a very stout design, and I'm happy they revised it.

The light press fit is for a reason. The supermiata is the same as the fluidampr and maybe they will chime in on why they are not selling them anymore. I don't believe either design can be optimized for more then one frequency. Also the closer the frequency is to the natural or an order of the natural frequency of the crank the higher the loading. So it makes sense to target that then a broad range.

This is actually super interesting to me, and the first "real" data I have seen like this (not that i can confirm sources or procedure) but this is really interesting and I guess I kind of have to think how high I want to spin it (which depends on if I go with BP05 I have or find a BP4W)

the crossover here seems to be right around 6200, which is certainly in the meat of the BP's power... but what really "concerns" me is the delta angle thereafter, it really seems the ATI significantly outperforms the fluidampr quickly, and the difference is really big around 7700; which, albiet, may be higher than I end up spinning it, but there is still the damping benefits anywhere beyond 6200

I was really leaning towards the Fluidampr, but now im not sure; I dont want to spend the extra money but...
Answers always lead to more questions.

However I will say, it seems fairly clear that any of these would be beneficial to add to the build :ugh2:

When I read that graph, I see the crossover right around 6,850 or so, at 6360 the fluiddamper is still well outperforming the ATI. For me, with stock head and a properly sized turbo, I see no need to spin it beyond 7200 or so, so the spike doesn't concern me as much.

FWIW those tests were done on a honda B series, not sure how that translates to our BP motors.

I can tell you the fluidampr on my car was a noticable upgrade in vibrations, particularly towards redline. I was getting fluctuations through my oil pressure gauge right around 6800 with the OE damper, and with the fluidampr those are gone.

Long story short, I'm sure any of these dampers are far better than the OE.

If it was a honda b series then it would be somewhat relevant since the architecture is similar. The bottom paragraph says something about a 58 chevy or something.

Ah, good eye. I found it on a honda forum, where they were discussing using the damper on b series motors. Maybe it says chevy SS, I.E. LS platform? Not sure.

A v8 with a equal number of main bearings, double rod throws and longer overall length will have a lower resonant/natural frequency. I'm not sure how that would effect the outcome.

I went with Fluid because of the company's far reaching aspects of industry. I would imagine their r&d department is far more comprehensive. Comparing the engine in the chart to a built bp motor is a stretch for me. Harmonics are different.

What about trigger wheel options between ATI and Fluidamper? It seems 36-2 or 4 are the preferred options with MegaSquirt.

ATI:
FM 36-2 trigger wheel
Fab9 4, 12, 36-2, 60-2

Fluidamper:
Fab9 4, 12, 36-2, 60-2

Any other options, especially for Fluidamper? I would chose FM over Fab9 any day based on other people's experiences.

I'm using a Fluidampr with the stock VVT trigger wheel, fits/works fine.

Funny you ask. I initially ran a fab9 36-2 on my fluidampr:

https://cimg6.ibsrv.net/gimg/www.mia...3d2afbecaf.jpg

I would never run that trigger wheel, or any with a similar design again (break-away tabs to fit both OE sized trigger wheel and ATI sized).

I switched to an FM 36-2, that was bolt-on, and works perfectly.

With the fluidampr the stock trigger wheel bolts right on, thus any aftermarket trigger wheel designed with the stock mounting in mind will work. Tons of options.