I have done a little research on the balancer or dampener setup on the subies. I have always thought viscous was better until recently when looking at ati info. Marketing always is questionable. I did buy the ati product but haven't used it yet. We will be using one soon on a 257 sti.

What I discovered while installing the ati was the difference in the 2.0 and the 2.5 stock dampeners. The 2.5 (all 2.5) na or otherwise use a three piece stock damper and the 2.0 is a two piece. I think this means subie is trying to control harmonics for heavier internals. The fact that the na motors also have the three piece balancer probably is because of the internal weight of the pistons and rods.

After looking at the ati info I want to control the harmonics at the front of the crank as much as possible especially at the oil pump.

I wonder how many guys use the wrx or two piece dampener on the hybrid builds with the 2.5 block and how many think the small light one piece pulleys are trick?

Oh yeah, I have a new perrin light weight and a knockoff light weight pulley set for sale if anybody is interested.

Charliew

I use the STI damper on my hybrid.
There are some lengthy debates by more than enough noteworthy members of nasioc about one piece lightweight pulleys that will persuade you either way. I'm not even going to touch that topic.
I read a lot of the discussions on corner carvers concerning dampers and, keep in mind these are mostly V8 guys (concentrated crowd of Mustang owners), they pretty much all agreed that ATI was superior to everyone else. It could be that ATI spent quite a bit more time/money developing a damper for that particular application than anybody else (a few members were actually part of the R&D team). So who knows if that carries over to other makes/models, but I sincerely hope the R&D team for Subarus had some highly knowledgeable members on board as well.
Since Fluidampr and ATI have both released dampers for our cars, time will tell which is best (or more highly regarded).

I emailed fluiddamper a couple of weeks ago and asked and they said they wouldn't have anything till the summer. Ati has already made me three and sent them. ATI's web page shows a better job of controling harmonics than a fluid dampener. Harmonics are the worst at the front of the crank, thats where the oil pump is. I use fluid damper on my sbc's and thought they were great. I think I made a good choice with ATI. I think they weigh 3.8 lbs. I have some lightweight aluminium pulleys for sale to anyone that wants to run them.

Charliew

fyi on the new imprezas the swapped pulleys between the turbos and NAs. there is no reasoning behind using either one and subaru claims they are not dampeners but rather just a crank pulley.

fyi on the new imprezas the swapped pulleys between the turbos and NAs. there is no reasoning behind using either one and subaru claims they are not dampeners but rather just a crank pulley.


Subaru does claim this BUT look at a stock one. It has all the components that are part of a damper. Hub, elastomer ring and a weighted mass outer ring.

As I said in the first post. The sti has two weighted rings with elastomer rubber inbetween them both. The wrx (2.0) has only one weighted ring. They are dampeners and are different from each other, one with a single ring for the 2.0 and another with two rings for the 2.5 with one ring on the outside like the 2.0 and one added on the inside where the crank bolt goes. I'm not familiar with the new imprezzas as in 07-08. If they are 2.5 I said all 2.5's that I am aware of use the two weighted rings whether they are na or turboed.

Charliew

My ATI damper just arrived... hopefully I will have some time to install it this weekend. I plan on logging some runs before & after. If my theory appears to be correct, I'll make a thread with my results and open myself up to be flamed for believing that lw crank pulleys w/o dampers are bad news. ;)

http://chrono.firex.org/images/ati.jpg
http://chrono.firex.org/images/ati2.jpg
http://chrono.firex.org/images/ati3.jpg

Sorry to bring this back from the dead but did you find anything out?

Ive been looking into getting one of these for my car and there isnt much out the to base off of.

I've been running it for a few months now. Nothing terribly noticeable but it's nice to have peace of mind during high rpms There were some differences in knock sensor readings but not enough to draw any real conclusions as I have a pretty noisy motor to begin with.

We got three about 1/25/08 and put one on wittmer 25's sti that we were assembling and I think we did the right thing. It's got to be an improvement over stock. The outside diameter is slightly larger than stock. It's wierd, the timing marks are not in the right place they say until the motor goes to about 2500 rpms the first time. I like the fact that they are rebuildable forever. My hope is that it will also smooth out the oil pumps flow by stopping crank flexing at all rpms and not as the stock one is designed to just be smooth at one or two different levels.

Charliew

Hi, I´m new here. I just bought the ATI damper and find the installation instruction a little confusing to me, did you guys have to hone the damper to fit properly or did it just slide in with some effort? I find it is a little too tight to fit easily on the crankshaft. I´d appreciate your comments.

It was tight on our motor also. I checked the ID and it was the correct interference fit so we put it on. The perrin I bought and installed on a wrx motor was also a interference fit. It was hard to remove also. I used neversieze to install the one we put on wittmer 25's sti. I know it's not as loose as the stock dampener but it needs to fit tight to work properly.

Thanks for the information charliew, I´ll give it a try with some antisieze then.

Does anyone know the weight difference between the 2.0 and 2.5 dampers? I'm in the process of building a hybrid and would like to use my old one but I don't want to cut corners that will cause future problems with my new engine