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Old 10-15-2003, 02:53 PM   #1
AMG Eater
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Default Perrin Crank Pulley...worth it?

I have heard good and not so good reasons to do this mod. Is it a worthwhile mod?
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Old 10-15-2003, 02:57 PM   #2
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Perrin claims it to cause no problems...therefore i ordered mine!
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Old 10-15-2003, 02:58 PM   #3
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i was also thinking about getting a perrin crank pully and the AEM pullys?
bump
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Old 10-15-2003, 10:40 PM   #4
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No harmonic dampener = I wouldn't order it. If it does cause issues, people aren't going to see them for quite a while.

-st
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Old 10-16-2003, 12:29 AM   #5
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There's a whole discussion about this product here .

The harmonic damper was also mentioned in this link. The point seemed to be the lighter the pulley (5.x lbs vs 1.2 lbs) the less of a need for a harmonic damper. I'm not an expert so i can't tell you if this is a perfectly correct logic but this claim along with the manufacturers claim of not wearing anything out was enough to convice me to try it out...

Last edited by GT2RS; 10-16-2003 at 12:35 AM.
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Old 10-16-2003, 02:06 AM   #6
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Default Re: Perrin Crank Pulley...worth it?

Quote:
Originally posted by AMG Eater
I have heard good and not so good reasons to do this mod. Is it a worthwhile mod?
Yes.
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Old 10-17-2003, 01:58 PM   #7
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FYI, I had one of these on my WRX and no problems. The STI also has an ADDITIONAL weight bolted inside the WRX pulley, so they must have put it there for a reason. I wouldn't be surprised if this mod would lose at least 6lbs off the crank. It's a shame that I didn't take mine off b4 I traded the WRX.
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Old 10-18-2003, 12:10 PM   #8
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Old 10-18-2003, 11:06 PM   #9
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Not a good mod. The only naturally balanced engines (that are common) are inline 6 cylinders and V-12s, all other engines are not naturally balanced and require proper balancing and or dampening aids.

Before I do any mod, I ask myself why Subaru didn't design it that way from the factory; because I trust their engineers. Why didn't Subaru add 30+ whp by replacing the exhaust with catless straight pipe? The reason of course is because they could not legally do that. Why didn't Subaru give the WRX 15 extra HP by porting and polishing the throttle body, heads, and turbo? Obviously that would be too expensive on an economy car.

When I ask myself why Subaru wouldn't gain an easy 5-10 whp by using a lighter pulley I can't come up with a satisfactory answer, so that tells me the Subaru's engineers think it's a bad idea. I also think it's a bad idea...
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Old 10-18-2003, 11:21 PM   #10
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Contacted Perrinperformance and here's what they have to say...

Quote:
The argument that the reduced weight and removal of the rubber ring will destroy the front main bearing is wrong! The rubber ring between the two halves of the stock pulley is to make up for mfr. differences. Two cheap cast pieces pressed together with rubber allows for additional slop in both. If Subaru chose to install a pulley like ours would add significant cost to the engine and is not cost effective for a production piece. The rubber ring is NOT a harmonic balancer! You should go to your car and let it idle. Raise the hood and note how the belts will track side to side and up and down. This is a result of the much less than precise pulley found from the factory. This causes undue stress and wear not only on the pulleys but on the belts and accessories as well. Installation of our pulley will result in smooth, true, and long lasting belt wear and accessory lifespan is increased. Plus, throttle response, HP and torque are all increased dramatically for such an inexpensive painless part.

Crank bearings, and rod bearings are much more prone to premature wearout from increasing boost than from installation of a precision made billet pulley. This should not be a concern.
Sounds good to me!
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Old 10-20-2003, 02:23 AM   #11
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Quote:
Originally posted by Corn-Picker
Not a good mod. The only naturally balanced engines (that are common) are inline 6 cylinders and V-12s, all other engines are not naturally balanced and require proper balancing and or dampening aids.

Before I do any mod, I ask myself why Subaru didn't design it that way from the factory; because I trust their engineers. Why didn't Subaru add 30+ whp by replacing the exhaust with catless straight pipe? The reason of course is because they could not legally do that. Why didn't Subaru give the WRX 15 extra HP by porting and polishing the throttle body, heads, and turbo? Obviously that would be too expensive on an economy car.

When I ask myself why Subaru wouldn't gain an easy 5-10 whp by using a lighter pulley I can't come up with a satisfactory answer, so that tells me the Subaru's engineers think it's a bad idea. I also think it's a bad idea...
Perhaps the answer to the issue that challenges you lies in the economic cost...after all, it is not a satisfactory answer to say that Subaru did not install a stereo to save weight. THey did not give us a stereo so that they could price the car in a certain targeted price range. Making small modifications to gain only slight performance enhancement is not usually something they consider when first releasing a new car. My guess is that when the competition adds some HP to their car, Subaru will go looking for those smaller modifications that might be more costily buy yield more HP.

I do not argue that the pulley may be harmful or safe for the engine. The fact is that I do not know and I came to this thread for answers. I just wanted to voice my two cents about your flawed logic, specifically:

Quote:
When I ask myself why Subaru wouldn't gain an easy 5-10 whp by using a lighter pulley I can't come up with a satisfactory answer, so that tells me the Subaru's engineers think it's a bad idea. I also think it's a bad idea... [/b]
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Old 10-20-2003, 03:38 AM   #12
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Harmonic balancers are on engines for a crucial purpose. To damp out potentially destructive torsional vibrations and/or resonant harmonics, not because a pulley is attached. These can be either fatique failures over time or catastrophic sympathetic vibration failure.

If you've experienced destructive crank vibration then you know what grenading an engine truly means. Generally I understand a four cyl is not as subject to this as a six or eight because of crank length. This exists in some general aviation aircraft also flat fours and sixes to the degree that operation at certain intermediate RPM between idle and redline is prohibited.

An inner metal ring and and outer metal ring separated by a rubber ring IS a harmonic balancer if attached to a crankshaft. No other reason for its existence. Whether the STI's balancer is well made or could be improved upon is something I have not looked into, but be sure if you're replacing a harmonic balancer with something which is not one, that the supplier is easy to find in case issues arise.

BTW, what does a factory replacement engine cost anyway?
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Old 10-20-2003, 10:26 AM   #13
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I did more search trying to see for myself that the aftremarket lightened crank pulley really does damage to our boxer engines. I found nothing to prove that and instead i came across this post by Subaru Rep. He said...

Quote:
According to the tech guys at SOA the boxer engine balances itself WITHOUT the aid of ANY form of dampener.

The pistons counter-balance the engine.
This is also helped by the fact that the crank uses 5 main bearings just like most other engines do except that our crank is about 1/2 the size of thiers so its able to withstand around 10 tons of preasure at any given point.

The main reason for a dampener is to help prevent crank walk and since the engine does not have to fight gravity in its running cycle there is no crank walk and hence no need for a dampening system.
I also found some posts by manufacturers (Vishnu, Unorthodox racing, etc...) discussing these lightened pulleys and they all back up what is said above. It was basically pointed out that stock crank pulley for Subaru is plainly just a crank pulley...not a Harmonic Balancer as also pointed out by SOA itself!
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Old 10-20-2003, 11:45 AM   #14
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Quote:
Originally posted by GT2RS
I did more search trying to see for myself that the aftremarket lightened crank pulley really does damage to our boxer engines. I found nothing to prove that and instead i came across this post by Subaru Rep. He said...

Subaru is afraid to admit that their engines are not balanced at all RPMs, as inline 6's and V-12s are as I previously mentioned; due to their two-fold axis of symmetry. The "not balanced across all RPMs" is why the boxer engines cause a noticeable wobble at low RPMs.

You quoted a Subaru Rep, someone who just repeated a few blurbs about the "perfect balance of the boxer 4" he learned from his yearly week of Subaru training, or something he quoted from a brochure he had laying nearby.

Quote:
Originally posted by GT2RS

I also found some posts by manufacturers (Vishnu, Unorthodox racing, etc...) discussing these lightened pulleys and they all back up what is said above. It was basically pointed out that stock crank pulley for Subaru is plainly just a crank pulley...not a Harmonic Balancer as also pointed out by SOA itself!
These are people who are trying to sell you something. These guys speak out of their asses on many subjects. I've seen Shiv of Vishnu Performance write articles about the ideal gas law and thermodynamics (dating back to the tapered exhaust debate) that were full of inaccuracies (calling them inaccuracies may be too kind).

There are much safer ways to make 5 whp. ICouldaBeenAV8 also raises some very good points in his post about what a proper balancer/dampener's job is and what happens when it's not there.
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Old 10-20-2003, 12:58 PM   #15
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Quote:
Subaru is afraid to admit that their engines are not balanced at all RPMs
That's great! I guess i have to return my subaru now!

Quote:
You quoted a Subaru Rep, someone who just repeated a few blurbs about the "perfect balance of the boxer 4" he learned from his yearly week of Subaru training, or something he quoted from a brochure he had laying nearby.
Not stated by Subaru Rep...by SOA Technician! I guess their wrong too.
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Old 10-20-2003, 01:10 PM   #16
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GT2RS would you please post a URL to the source of the quote from the Subaru tech. Also is this person an SoA employee or just a tech working for a Subie dealership (not SoA employed).

I'm going to give it a go as my next planned mod...

- Janq
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Old 10-20-2003, 02:04 PM   #17
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Tech is from SOA. If you search for "Crank Pulley" and "SOA" the link sould show up. I think it has like 4 pages on it. I'm contacting SOA right now too so if you want you could just wait for that...

Believe me i wouldn't want anything bad on my car either but nothing seems to prove to me yet that a lightened crank pulley will have any harmful effect on the boxer engine! Besides i haven't seen anyone with a subaru post yet blaming the pulley for any engine failure.
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Old 10-20-2003, 02:56 PM   #18
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Quote:
Originally posted by GT2RS
Tech is from SOA. If you search for "Crank Pulley" and "SOA" the link sould show up. I think it has like 4 pages on it. I'm contacting SOA right now too so if you want you could just wait for that...

Believe me i wouldn't want anything bad on my car either but nothing seems to prove to me yet that a lightened crank pulley will have any harmful effect on the boxer engine! Besides i haven't seen anyone with a subaru post yet blaming the pulley for any engine failure.
Thanks!

Readers, for Internet/NASIOC results against the above keywords go here; http://search.msn.com/results.aspx?s...y%22+%22SOA%22

I'll await the results of your contact with SoA.
BTW, just ask if the crank pulley is a pulley of if its truely a balancer. If you ask about it being okay to replace with a non-OEM part they'll tell you no by default.

- Janq
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Old 10-21-2003, 01:02 AM   #19
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This is real easy. I haven't looked at an STI engine crankshaft end to determine if a harmonic balancer is present and don't know enough to say definitively. If there is just a pulley and no harmonic balancer then I would say you could change to any kind of pulley and maybe be better for it if it is lighter or runs truer or just looks better.

But, if there is a inner metal center separated from an outer metal ring by some sort of rubbery material you are the proud possessor of a harmonic balancer on your STI. That means someone at Subaru deemed it necessary no matter what someone else in or out of the company says.

What that also means is that unless your're engaging in short duration racing (dragracing), you need to make sure the replacement gizmo is a harmonic balancer or you may be shocked at the results..
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Old 10-21-2003, 01:06 AM   #20
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OOPs! The previous post was actually from "ICouldaBeenAV8". Nivek, my kid, commandeered my computer and naturally did'nt change back after logging on.
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Old 10-22-2003, 10:24 AM   #21
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Quote:
Originally posted by Nivek-CA
I do not argue that the pulley may be harmful or safe for the engine. The fact is that I do not know and I came to this thread for answers. I just wanted to voice my two cents about your flawed logic, specifically:
Nivek, I don't see where corn-picker's logic is flawed. All you did is point out there could be an economic reason as well.

Unlike the stereo, using a lighter pulley is not an economic choice. It would cost Subaru nothing. There is no emissions concern. There is no safety concern. So that leaves reliability reasons, no performace gain, or driveability loss, etc as reasons not to use a lighter pulley with no dampener. These are things that us, the owners, are concerned about unlike cost, comfort, and maybe emissions.

-BrianK
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Old 10-23-2003, 04:00 AM   #22
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Quote:
Originally posted by briank
Nivek, I don't see where corn-picker's logic is flawed. All you did is point out there could be an economic reason as well.

Unlike the stereo, using a lighter pulley is not an economic choice. It would cost Subaru nothing. There is no emissions concern. There is no safety concern. So that leaves reliability reasons, no performace gain, or driveability loss, etc as reasons not to use a lighter pulley with no dampener. These are things that us, the owners, are concerned about unlike cost, comfort, and maybe emissions.

-BrianK
Let me take a shot in the dark and say economies of scale.
Could it be the balancer on the STi is the same as the 2.0L?

If so and I were Mr. Subaru I'd say use the same one too as its one less item that needs to be manufactured & stored special to the STi, which maximizes my profit through reduction of cost to build per unit.

If not and its different I'd say its there for a purpose that some engineer somewhere feels is important. I mena these are the same guys that spec'd out the car to include the weight of the driver so as to provide balance when the car is laden (!).
Its not likely they'd skip over such an item knowing the car will rev faster with a lightweight unit.

Even still in the end its unlikely we'll see any eveidence of problems with this mod for many miles down the road. For most of us that item is moot as we'll have moved on to bigger & better and no doubt will have sold the STi for the latest new toy in a year or three.

Myself I'm willing to take the risk and bet that all will be fine.
The mod is number three on my list of 'To Do' items for my STi.
Besides folks are running turbo backs, plugging in UTEC's, running higher boost , bigger turbo's and all manner of power gain mods that will stress the engine a lot more than this relatively lightweight (pun intended) mod. I just don't see it as that big a deal especially on an inline four. If it were a domestic V8 I might not feel the same.

- Janq
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Old 10-23-2003, 04:08 AM   #23
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how does the zero sports one compare tot he perrin one?
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Old 10-23-2003, 04:57 AM   #24
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I love it, talk about improved throttle response
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Old 10-23-2003, 02:16 PM   #25
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I finally got an answer directly from Subaru of America...I asked them if the crank pulley for the WRX and the STi is used as a harmonic damper/balancer. Here's the reply...

Quote:
Hello F. Flores:

Thank you for your patience as I checked with our Technical Services
Department regarding your message below. They advised that the crank pulley
is a pulley and nothing else. It is not used as a harmonic damper/balancer.

Thanks for the opportunity to be of assistance. If you need any future
assistance, please feel free to contact us again.

Best wishes,

John J. Mergen
Subaru of America, Inc.
I think this topic can now end!
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