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Old 02-17-2009, 06:21 PM   #51
06HAWKMAN
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IMO the pulley doesnt give enough gains to warrant the engine life decrease and worry.
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Old 03-21-2009, 06:12 PM   #52
mongolloid
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So I have a new pulley ready to install. I was looking at the stock pulley turn with the engine on, and I noticed the bolt didn't look like it was rotating perfectly. Is that natural?
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Old 03-22-2009, 04:09 AM   #53
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Any imperfection on a rotating source will make it appear to be out of balance, this goes for a pulley or the bolt. Optic out of balance will cause no harm except to your brain if you think about it too much.
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Old 05-27-2009, 12:29 AM   #54
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how come no one could give me a straight answer if ps pulley could be removed on 02 bugeyes?
need answer!!! some says it can be removed some say not. cannot find answer anywhere on google! don't want to waste money on puller if pulley cannot be removed. bought unorthodox kit from spo motor and he thought that all ps pulley could be removed on subies. we're both researching the issue. and if the unorthodox ps pulley will bolt on?
http://spomotorsports.com/AddToCart....tomerID=237525
http://www.gfb.com.au/index.php?pare...ub_option=2001
http://fastwrx.com/gobithpipuki.html
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Old 05-27-2009, 11:02 AM   #55
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There is an excellent write-up on this, I believe on the Group A website or on IWSTI. Basically, somewhere in '02-03 subaru started using PS pulleys that bolt on. Early cars got press-on pulleys. The pulley is NOT replaceable if you have the press-on pulley. Mine is like this. It just looks like the end of a metal shaft, no bolt head. The transition was not distinct, so you have to look at your car to tell. Subaru then used two different teeth patterns on the removable pulleys. Some are "fine" and some are "coarse". There's some chance that a certain color pulley will be a certain tooth profile, but the only way to tell for sure is to take your pulley off. Later cars generally have used the fine tooth pitch, which is what my '08 sti has.

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Old 06-04-2009, 12:39 AM   #56
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Quote:
Originally Posted by unclemat View Post
Is there an engineer who looked at the stock crank pulley and can definitely tell whether it's a dampener or not?
I'm not an engineer but I am educated, familiar with physics and basic engineering principles, and worked in an automotive machine shop building racing engines for awhile.

If the stock pulley has a rubber insert in it, then it is a damper, plain and simple. You don't have to be an engineer to realize that if there was no need to dampen vibrations there would be no need for the extra manufacturing complexity of building a pulley with a rubber insert in it.

What vibrations is this pulley supposed to dampen? I dunno, I'm not a Subaru engineer, but the technical document posted earlier gives us a clue and I can relate what I know about harmonic dampers (or dampeners) based on my experiences with American V8 engines.

Every time a cylinder fires there is stress imparted to the crankshaft through the piston & rod. This stress bends and twists the crank a little bit. As the cylinder pressure rapidly falls off, the crank, being made of an elastic material, unbends. There is actually a very minute oscillation that takes place, just like a car spring with no shock to dampen it's vibrations. This bending/twisting happens several thousand times a minute at higher RPMs creating harmonic vibrations in the crankshaft. On old American V8s the factories installed a heavy chunk of steel with a rubber insert and a thick metal ring around the outside of it to both dampen and absorb these harmonic vibrations.

As the dampers or balancers aged and the rubber insert wore out it wasn't uncommon for that outer ring to slip with relation to the inner ring, causing at least two problems. First, the outer ring might no longer be concentric with the centerline of the crank, setting up it's own stresses on the crank as it spins. Second, the rubber and outer ring are no longer doing their job of absorbing the vibrations imparted to the crank by the cylinders firing. On old Pontiac V8s with cast iron crankshafts this often led to the crank cracking right behind the #2 main bearing. It's interesting to note that in the late '70s when V8 power was being choked by emissions regulations and lack of technological innovation that the low performance versions of Pontiac's 400 ci. V8 (165-180 HP from 6.6 liters!?!?!) got nothing more than a solid hub on the end of the crank, not a harmonic dampener as in years past. Apparently the engineers figured these pathetically low powered engines couldn't stress the cranks enough to hurt them any more.

The Subaru engine is obviously a very different design, and maybe the crank is way over-engineered for the application (sort of like those Pontiac cranks in the late '70s) but that crank is still getting twisted and bent by the power pulses from the cylinders. A piston ICE is a piston ICE and the same basic principles apply to all of them regardless of design. Perhaps the layout of the engine is such and the materials of the crank are such (good forged steel is much better at resisting fatigue from repeated torsional forces than cast iron, and maybe the boxer engine layout stresses the crank less than a V8 layout) that it isn't really much of an issue with these engines. Again, I dunno. What I do know is the engineers had some reason for designing the stock pulley the way they did and since I need my car to be more or less bulletproof reliable and last as long as possible (I have a 6 yr. loan on it...) this is one mod I won't bother with as the small gains in performance aren't worth the **possible** decrease in longevity to me. I'll stick to increasing airflow through the engine and reducing wheel weight to gain performance secure in the fact that even if this is the most harmless mod you can make and I'm leaving 10Hp on the table that there will always be someone faster than me anyway, and I have a reliable and still fun to drive DD.

There's my opinion, worth all you paid for it. Do what thou wilt.

Last edited by Chainsaw_Willie; 06-04-2009 at 02:45 AM.
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Old 06-04-2009, 11:22 AM   #57
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I would hate to beat a dead horse, but even some vendors are listing pulleys as "possibly decreasing engine lifespan" over a harmonic dampener/lack thereof:
http://fastwrx.com/bilalcranpul.html

No consensus yet, it seems....
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Old 06-04-2009, 12:01 PM   #58
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There is a consensus, but the tin foil hat people just don't want to believe it as they'd rather be argumentative based on theory and zero facts vs. the 1000s of us who have had pulleys and no problems. This is America and you can argue and e-thug this issue all day though, so have fun with that.

<-------turned 100,000 miles the other day on a lightweight pulley
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Old 06-16-2009, 07:10 PM   #59
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i had an unorthodox racing set on my old gsr, long since stolen, for about 60,000 miles with no issues whatsoever, other than a nice hp gain across the whole powerband. i knew all the guys there, and they all ran them on their cars as well.
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Old 07-27-2010, 05:17 PM   #60
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reviving an old thread here but can anyone that has/had a pulley post up how long they have had it on their cars for.
I'm looking into getting a light weight one simply due to the fact that my oem one i think is gone. (engine vibrates on accels and decels, you can search my thread in 2.0L powertrain "engine/Chasis vibration") I have narrowed it down to the crank pulley. so i called subaru and the oem part costs 230$ and a light weight one shipped to my door is around 160$. Hense why I think I want to purchase a light weight pulley.

so if people reading can put up their numbers with their lightweight pulleys i want to see if there are long term effects. (the intial thread began in 03' i think)
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Old 07-27-2010, 05:27 PM   #61
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I've had one on my car for about 4 years now and haven't had a single issue with it. Had to change the belts couple of months ago, but that was due to age and heat cycles..
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Old 08-26-2010, 04:18 AM   #62
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Curious, has the design of the pulley/dampener changed over the years? I noticed about 1989, but I'm interested in 2002-10
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Old 09-20-2010, 04:09 PM   #63
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I have a unorthodox underdriven pulley. Been on my '02 Legacy for 7 years now. No prbs, and I definitely noticed a little extra throttle response when I put it on. I think the blue makes it go faster too
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Old 01-10-2011, 11:51 AM   #64
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Another thing to consider here is the crank is also attached to an even larger chunk of rotational mass, the flywheel.

Assuming the crank is well-restrained within the case by the main bearings, the vibration at either end of the crank should be minimal, since the crank is nearly symmetrical with regards to its geometrical shape and loading pattern. Personally, I see no problem with running a lightened crank pulley and plan on running one in my FSXT.
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Old 01-10-2011, 12:04 PM   #65
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Unabomber does it again!
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Old 01-10-2011, 12:11 PM   #66
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I have been running a LW/UD crank Alt & PS pulley kit since 03 on my 02 with out any ill effects......and thats at 391whp out to 7k rpm weekly. Also price is very overrated, meaning the cheep ebay kits are fine as long as they are a one piece pulley stay away from the bolt together power steering pulley
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Old 01-13-2011, 09:50 AM   #67
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awesomeee
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Old 01-27-2011, 11:00 AM   #68
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I have a Vishnu Underdriven Pulley on my 2.5i, I notice that theres a few issues with voltages and lights dimming and etc.

If I switch to Perrin LW pulley, would it show any improvement or else?

Is there any certain difference between a UD and LW pulley? Performance wise.
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Old 01-27-2011, 12:27 PM   #69
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UD pulleys in theory would net you like 1 more HP, but for most the electrical wonkiness and pain in the ass sized belts make them not worth it. You elec issues will go away and the -1 HP you won't feel.
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Old 02-03-2011, 09:19 PM   #70
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I had the old Perrin LW pulley (before the "star" pattern) on my '02 WRX and didn't have any electrical problems. Noticed some decent acceleration gains- overall HP, not sure. Once I paired it with a LW flywheel, I had better acceleration again, but trying to coast in gear was not going to happen. There wasn't enough rotational mass, so it created a huge engine brake. Not a problem, really, but was a bit awkward at first since I hadn't thought about it beforehand. Easy fix, put it in neutral. ha ha
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Old 02-22-2011, 03:04 PM   #71
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Subarus do not have harmonic balancers, they have metal pulleys. Replace it with a lighter version and you will have no negative afteraffects. Replace your pulleys with underdriven units and you may have voltage issues. But you will not shorten engine life with a lighter pulley or increase the chance of harmonic vibration damage as you would with a vehicle that comes with a harmonic balancer (V8 for example).
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Old 04-11-2011, 06:33 PM   #72
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I figure I share this:

http://www.atiracing.com/products/da...dam-subaru.htm

The only crank pulley I seen for sale that is SFI 18.1 Safety Certifications (bold claim to make because if it is the opposite, they could have a class action lawsuit on their hands).

Why don't other companies say that about their pulleys or submit their pulleys in to get the SFI 18.1 certification? This is an honest and curious question. I never thought about changing out my pulley, but it sounds interesting to do. My only worry is not enough rotational mass to maintain engine idle when coming to a light while the AC is on.
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Old 04-11-2011, 07:44 PM   #73
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I have had my non SFI 18.1 pulley for 135,000 miles now. Now you ask yourself why we need this certification and get back to us.
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Old 04-12-2011, 10:44 AM   #74
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Quote:
Originally Posted by Unabomber View Post
I have had my non SFI 18.1 pulley for 135,000 miles now. Now you ask yourself why we need this certification and get back to us.
Actually that is all part of my question.

I figure if my question can be answered (and can be referenced), then I will jump on-board.

A buddy of mine has the pulley from the link provided, on his 2010 STI. Lighter, doesn't stall the engine when coming to a stop or when the AC is on, and revs much more quickly than the stock pulley, all without any added engine vibration versus the stock.

So that is why I posted my question. If someone can answer it, I am going to get the ATI Racing pulley. If not, I'll just move along.
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Old 04-12-2011, 11:33 AM   #75
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Because SFI 18.1 certification costs $XX,XXX and that cost will be passed along to you, hence a Perrin Pulley is like $110ish and the ATI one is like $400ish. Feel free to buy what you like, but there is no issue with a "cheap" pulley.

I'm also not cozy with their terminology. "exceed SFI 18.1 specs" is how they put it. Well, EVERY part that exceeds a spec will by itself "exceed" the specification. No need for marketing double speak. They are listed on http://www.sfifoundation.com/ so they are legit though.
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