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Aight my next mod is going to be a UDP, probley FC 2 piece. My question is, how does a aftermarket pulley give you more WHP? Is it because they are lighter then the stock ones? I can see how other things like a throttle body, exhaust, intake, ect can give you more WHP but I can't see how a aftermarket pulley can. Anyone know?
 

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They produce power by relieving power wasted in the accessory belt system. A smaller pulley will supply less energy to your accessories. A lighter pulley will have less parastitic loss and produce more power by turning a less massful object. Also, pullies do not make power, they free power up that was already there but being used on your accessories. This bolt on is the best dollar for power mod you can get.
 

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it doesnt even really steal power from your accessories either, the fc does more so than the afx but u will see better gains than the afx. in reality, its just less rotating mass in the belt drive system.
 

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Discussion Starter #5
EuroZX3 said:
it doesnt even really steal power from your accessories either, the fc does more so than the afx but u will see better gains than the afx. in reality, its just less rotating mass in the belt drive system.
ok im confused on one part. Does the afx produce more gains then the FC or is it the other way?
 

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afx does. the only pulley that needs to be replaced is the crank. the fc water pump pulley is actually larger than stock, the same dia as the stock crank pulley, but in doing so it allows use of the stock belt. i actually had a problem of my car over heating during the summer with the a/c on when i had my fc pulleys
 

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Just replace the crank pulley. Replacing the others, in my opinion, are a waste of time
and money with little or no additional gain.
I believe just about any of the crank pulleys are going to give pretty much the same results whether it's from Ford Racing, Focus Sport, Focus Central, etc.
 

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I sold my FC pulleys before trading in the old Focus. Too damn hot in a black car in the summer. I am thinking of getting the FS one with the belt though.
 

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Well, I did a search to see what the best ones are.
So Euro, you say that the AFX ones are the best? I'm gonna get UDP's soon.
But then again, are the FC ones any good?
 

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My 2¢........1. Go with a single crank pulley 2. Which one?There is so little difference it doesn't matter. I doubt you will be able to feel any difference between the AFX, FC, Mac, FS, Ford Racing, etc. Let your budget and ego be your guide, lots of money to spend and you want to be able to tell people you've got a FORD RACING UDP then go for it or if all you want are the benefits of an UDP and a small budget then choose one of the others based on price.[thumb]
 

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Well, I see that quite a few people like them.
I might end up going with them.
 

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the fc is decent, water pump bolts can come loose, and i noticed a lot more less a/c power with the fc than the afx, and also over heated once with the fc.

ill just say ill never go back to the fc after having this pulley
 

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For 2 or 3 hp the UDP is just to expensive and negitivly affects the air conditioning to much. I wish that a company would come out with a lightweight stock pully though. It would rev better with the lighter weight.
 

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the thing is, every UDP is going to throw the balance off of the crank because the stock one has a specific weight to keep it balanced. the afx wont hurt your accessories at all, my car never comes close to over heating, actually seems like it runs cooler, my alternator has no probs, i can still run my amp which is hugeeeeeeeee off of it. the only thing is u throw off that harmonic balance. which im really not sure how bad that is
 

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Harmonic balance, that seems to be the $64,000 question. Internally balanced, externally balanced we have all been part of or witnessed the "great debate". I have yet to see where anyone has stepped forward and documented damage as a result of a UDP. If there have been related incidents I'm sure we would all like to hear about them. Many tech guys say it is not a good thing but we have members who claim they have run a UDP for years with no adverse effect...........who knows, I wish I did, I have a UDP but can't help and wonder sometimes if I have a bomb ticking under my hood??????????[paranoid]
 

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i believe the problem lays in the harmonic damper. it uses a rubber like polymer to protect the crankshaft from vibrations and whatnot.


alright guys good stuff here.

i just got off the phone with fred @ http://www.fluidampr.com fred helped me out a lot with undestanding how the harmonic damper works.

the harmonic damper is a elastomeric, or rubber like polymer in the crank pulley, that is more or less tuned very specifically via thickness and hardness to match up the frequency and vibrations, all in an effort to reduce torsional twist.

fuldampr makes dampers with silicone substance to control vibrations at all rpm.... heres a small info page on them. http://www.fluidampr.com/solution.html

according to fred, they hope to be jumping into the sport compact scene and possibly make something for the focus soon.

thinking about this more, after i installed my fc pulley i noticed a vibration at a very specific rpm, around 1500-2250 maybe even 2500 and i didnt pay much mind to it because i thought it was just my volant box vibrating. the vibration wasnt as bad with the afx vs the fc but now im pretty sure it must be from the crank.

isnt the focus crank supposed to be pretty tough??

anyway, i invited fred to come and join the site and maybe shed some more light on this so hopefully we will see him on here soon.
 

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Well that sounds cool.
It's just that the reason why I haven't gotten a UDP yet is because I had my doubts and I heard that it would take the power away from your AC. I just need to learn a little more about them.
 

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The only reason the Focus has that rubber ring on the stock pulley is to reduce the vibration of the accesories. Think about it. Do you think that the little pulley on the end of the crank is going to have much of an effect on the vibration of a crank that has multiple bearing journals guiding it and is attaced to a huge flywheel on the other end that is transferring all of that rotational energy to a transmission? The Zetec is internally balanced. The amount of stress that those accesories put on the crank is miniscule in comparison to the stresses it's receiving from the flywheel and pistons. Definitely not enough to keep me from using a UDP.
 
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