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Discussion Starter · #1 · (Edited)
Ok so I searched- here and I-club. The war is raging over whether a lightened crank (edit:) ) Pulley is hazardous to our engine.
I would like to hear some of the heavy hitters on this board hash out their views cause my Perrin just came in and I'm really swayed right now to sell it.
Put me at ease people!! I want my sube to last 100k no more- no less.

thanks

Rick
 

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Discussion Starter · #5 ·
So with the argumenst AGAINST aftermarket pullies- which would be the most harmfull just lightened or lightened/underdriven?
I just got the Perrin which is just lightened.


thanks


Rick
 

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That's where the argument resides. If the stock pulley really is indeed a harmonic balancer, then that would mean that even if you just replaced it with a equal weight UD pulley, it would still be off since it isn't balanced with the crank. If you look at some stock pulleys, you'll see that some material has been taken off. The assumption is that it was done to balance the pulley with the crank.

If the stock pulley is not a harmonic balancer, then you can do whatever you want. The only downside to the UD pulley is that it can cause your lights to dim in certain circumstances, i.e. powerful stereo system drawing lots of current from the alternator.

Of course there are other arguments, such as Shiv's, which is to say that having a balanced pulley on the crankshaft doesn't really matter if the engine is not running high RPM's on a consistent basis, i.e. like a racecar. Since the WRX engine'd torque curve drops off after 5500rpm, the reasoning is that there wouldn't be enough torque to actually do any damage. At least that's the way I understand it based on what he posted.

The other thing you have to keep in mind is that I'm sure a lot of people have put pulleys on their cars and knowing the rules of the internet, we all know that most people don't complain when something works, but if it doesn't, they'll complain like there's no tomorrow. Taking that into account, I've only seen a few posts regarding problematic idling with a pulley. This can probably be accounted for by the fact that not all cars are exactly the same. For these few people, their engines don't like the pulley. But think about everyone else that's running it without any problems.

Just like everything posted on the internet, you have to take it with a grain of salt and use your own reasoning and judgement.

Calvin
 

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Woah there! This thread started out by asking about a lightened CRANK. Now we are discussing lightened PULLIES. Big difference guys. In Pace-speak at least, the crank is what your conrods are connected to and is what converts up-down motion into circular motion.
:eek:

The initial question kinda threw me for a loop (a lightened crankshaft.. wow!?)

I guess it's pretty obvious now that you were referring to replacement pullies... sorry if my initial response caused some confusion. I actually have no experience whatsoever with lightened pullies of any sort, crank or otherwise. I was under the impression it was a pretty safe mod on the EJ20 which is inherently quite a balanced motor. From reading that thread it is apparently not such a cut-and-dried issue.

I guess my approach would be to try them for yourself and see what happens.

-Pace
 

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Hey Pace,

I think that Rick was referring to the crank pulley the entire time, but he didn't outright state it. The only way I knew what he was talking about is because I've been keeping up with that post he referred to. :)

Calvin
 

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That's a very interesting thread (the nested one). The only observation I had beyond what was mentioned was that one guy said that after addition of the pulley triggered the knock sensor, the running of race gas temporarily 'cured' the problem. How would this really be so unless actual knock was occurring. The general consensus in that thread however is that the lack of harmoning dampening is what is erroneously triggering the knock sensor. Unless of course the knock sensor was being triggered due to a combination of minor detonation plus the engine harmonics. Removal of the minor det by running race gas might then move the overall noise below the knock sensor threshold.

After reading that, I would definitely be a little hesitant to run one for an extended period although I might still experiment. I personally know Larry (hotrod) who has a very strong engineering background. I would tend to accept his diagnosis over the word of the tuner that contributed to that thread (and who is the manufacturer of the culprit crank pulley). No offense intended to said tuner.

-Pace
 

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cnk said:
Hey Pace,

I think that Rick was referring to the crank pulley the entire time, but he didn't outright state it. The only way I knew what he was talking about is because I've been keeping up with that post he referred to. :)

Calvin
Absolutely. I realized that when I started reading down and you guys all responded with reference to the pulleys...

Just a simple obfuscation of terminology is all. "No big deal."

-Pace
 

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Discussion Starter · #11 ·
Oops - forgot a word (pulley), I was thinking faster than I was typing I guess.

Sorry guys.

I'm kinda torn on this one- I guess I should have read up before I ordered.


thanks for your help


Rick
 

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In your position, I'd probably feel the same way. Thing is it really is a small horsepower gain, and while it's pretty good bang for the buck I think there are less questionable ways to gain the same amount of horsepower (an uppipe, for example). Even if you don't have the knock-sensor problem, it seems plausible that damage could result over an extended period of time.

-Pace
 

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Discussion Starter · #13 ·
Since I dont think I've ever listed it- Here goes.
I got the car 3 months ago. I cant stop modding!
Pace- I hold you and Jim somewhat responsible.

03 Platinum Silver 5 spd
TXS Uppipe/Stealth back exhaust (to the axyl)
Prodrive axyl back w/kartboy hangers
Samco Radiator/intercooler hoses/Intake inlet pipe
Resonator intake Mod
ITG filter
Kartboy Short Shifter w/bushings
Autometer Boost/EGT gauges
Platinum Tint
Zerosport Intake pipe
Dead pedal /frontplate/wastegate cover from Autospeed Performance
Autospeed shifter trim
MOMO Race airleather knob
Lightened Perrin crank Pulley-- Bought, might not be installed
I even bought one of those STI keys!

Chip, colder spark plugs- soon
Rims tires- spring
Racing suspension summer

Then I'm DONE!!!

Rick
 

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Before you read GFB's take on it I will mention that I have been having problems with my knock sensor acting up. After what was mentioned I wonder if my pulleys may have somthing to do with it. Makes me wonder if that may be the problem.

When using a GFB Power Up Pulley Kit, is there any problem with the removal of the harmonic balancer?

Since the crank pulley in our Power-Up Pulley Kit replaces the factory harmonic balancer, people often express concern for the effect that this will have. It is important to understand the task of a harmonic balancer and why they are fitted to explain the effects of fitting a lightweight pulley.

What is a harmonic balancer?.....

A better name for a harmonic balancer would be "torsional dampener" since its main task is to absorb the rotational pulses inflicted on the crankshaft by the pistons. Most often it is incorporated into the crank pulley by attaching the outer belt drive ring to the inner by means of vulcanized rubber. At the right RPM, it is possible for a resonant frequency to be set up torsionally on the crankshaft. Resonant frequency occurs when the pulses of the engine correspond with the natural frequency of the crankshaft and it ancillary components. However, since factory pulleys are often comparatively heavy (reasons for this are described later) it is actually the large mass (and therefore inertia) of the factory harmonic balancer and flywheel that will help to excite this natural frequency. So by dramatically reducing the weight and inertia of the crank pulley, the natural frequency of the crankshaft is shifted and its ability to self-excite is greatly reduced. So in fact it is the harmonic balancer's own weight that necessitates the dampening, and since the weight of a GFB crank pulley is typically about 20% of the factory component it cannot supply an exciting force significant enough to damage the crankshaft.

An opinion often expressed is "if the manufacturer put it there, it must be there for a reason". However, if you look at it from the car manufacturer's point of view, casting pulleys from steel is very cheap and easy, because they can be produced in large numbers and there is no waste (as opposed to machining them from billet). But because the resulting pulley weighs significantly more than one made from aluminium alloy, it requires dampening.

Manufacturers will always build cars (even high performance cars) to suit the widest possible selection of driving scenarios and drivers, which means there are always compromises. The weight of the flywheel and pulley also affect how fast the revs drop between gear shifts, and a production car is designed to only allow the revs to drop fast enough for average shifts. If you hurry the shift the revs will be too high for the next gear, resulting in a sharp jerk as the momentum of the engine transmits through the drivetrain. Reducing the engines' inertia with a lightweight pulley kit allows faster and smoother shifting.

When looking at high performance engines such as those found in Honda VTEC equipped cars and the S2000, it is obvious that manufacturers do understand the benefits of reducing engine inertia, and have utilized lightweight pulleys to help the power output and responsiveness without the use of a harmonic balancer.

However, this is not the case for all engines, many of them do require the use of the harmonic balancer to prevent failure. Skylines with the RB20, 25 and 26 are a good example of this, which is why we don't make a pulley kit for them. The pulley kits we do make are for engines that do not rely on the balancer to any significant degree.
 

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Discussion Starter · #16 ·
My tuner (who will remain nameless- wouldnt want him to get bombarded with e-mails) is calling bull * on the whole "lightened pulley are evil" debate.
Said he has never seen a problem-
I guess the best answer to this problem would come from an Australian or Japanese tuner who have been doing these upgrades for years and years.
I'm going to wait a few weeks on the Perrin pulley until we get some more people to chime in.

thanks guys!
 

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Discussion Starter · #17 ·
Jeff Perrin's response.

Rick, first thanks for purchasing the pulley. As for the harmonic balancing thing, It is true that some cars need a harmonic balancer( mainly big old V8's and some newer imports) But as for the Subaru and most other high performance smaller engines, they don't need them. Aftermarket companies have been making pulleys for Subaru for years now and have had no ill effects on the water pump or bearing life, or the oil pump.
In the past cars have had problems with these going bad, but the Subaru drives the water pump from the timing belt. The oil pump is driven off the cranks nose and has the oil running through it which is a dampener in it self.
Another thing to make you feel better is look at how many years the Japanese tuners have been putting crank pulleys WRX's (since 95). You would think by now that if there were any problems, they would have been the first to know.
Hope this makes you feel better, I know on iclub some people were complaining about Vishnu's pulley causing check engine lights and making the car run funny. I think his pulley or anyone else's pulley is not the cause of this, it was just a coincidence.
Anyway, I hope this wasn't too much info, talk to you soon.
Best Regards
Jeff Perrin
Product Engineer
Perrin Subaru Performance
 

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I appreciate that many if not all of these tuners are likely far more knowledgable than guys like me on subjects such as this. However, the 'it's a coincidence' spin just doesn't sit well with me.

- Fit the pulley. Get a CEL.
- Refit the OEM. No CEL.
- Fit the pulley. Get a CEL.
- Refit the OEM. No CEL.

In all the cases of the Vishnu pulley related CEL reports, that pattern was present. That's not what I would call a coincidence. (Put my hand in the fire. It get's burnt. Put it under cold water. Feels better.)

I also don't buy the whole thing about the rubber dampener only being needed to damp the resonance created by the wheel it is fitted to. This is kinda like fitting a rear wing who's only purpose is to improve an aerodynamic inefficiency created by the fitment of a rear wing. It's like a circular riddle where the component is the solution to a problem created by it's own presence!

I think I'll use my own better judgement on this one. I tend to agree with Trey Cobb's observations of the problem. I guess it's just a 'coincidence' that he doesn't manufacture and sell a lightened crank pulley. I really wouldn't expect any vendor to tell us that a product they manufacture and sell is detrimental to our motors in the course of it's normal operation.

-Pace
 

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AaronC said:
Before you read GFB's take on it I will mention that I have been having problems with my knock sensor acting up. After what was mentioned I wonder if my pulleys may have somthing to do with it. Makes me wonder if that may be the problem.

Given similar reports, I'd say it's highly likely that this is exactly your problem. Refit the OE crank pulley and report back with your findings. :)

-Pace
 
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