Racing Crank Pulley

[bobmeindertsma]

I was just cruising the new and fell upon changing the crank pulley to add more horsepower.

has anyone here done this and if so did you get noticable
hp increase?

[Sundi240]

If you mean underdrive pulleys, they will yield a little power (5hp or so), costs fairly cheap ($100CDN or so). Do not buy them if you have a sound system or if you use A/C a lot. U/D Pulleys take power from those areas to give most to engine as possible.

[bobmeindertsma]

5 hp is 5 hp:D
but thanks for the tip

[sykikchimp]

there have also been questions as too the loss of the weight allowing the crank to vibrate more, and possibly shortening the life span of the engine. But, real world experience has shown that many people have had them for a good 3+ years, and had no trouble.

btw - The asp pulley is about $100 cheaper than the UR pulley, and weighs about 1 pd more.. they say that is intentional to help reduce the aforementiooned affects.

[Dream240]

I actually called UR and asked them about that damaging affect, and the guy I spoke to said that they have making the pulleys for over 10 years now and never had any problems reported regarding damaging the engine.
Also as far as power gains, Import Tuner did 2 test in recent issues with the UR SS pullet kit on 240s,one showed a max gain of 12 hp at 6000 and the other was only 3-4 hp. They say it was due to bad/loose belts, I think overall you'll get 5-10 between 3000 and 6000 on average which isn't too shabby!!

I say get em.

[old_s13]

Just incase you guys are interested, parts for sale:
http://www.zilvia.net/f/showthread.php?s=&postid=283576#post283576

[bobmeindertsma]

hmm maybe it wouldn.t be such a bad idea to get one.
have any of you guys done this mod?

[thx247]

pulleys....why not just pull the AC pully off for a little bit and see if you can even tell the difference in power. Its free and you might be suprised at the "difference."

Pulleys are lighter in weight than the stock pulleys yes, thats not why they um.."make" so much more power though. They basically spin the AC, PS, alternator and water pump less, because those components are moving less, there is less parasitic drag on the motor, thus freeing up hp.


Are they worth it? Um...I dunno. Hope you don't have a sound system that draws on your alternator heavily because you will notice problems there. Putting more strain in the other components of the system by reducing their operating pressure is not my idea of a good mod.

OH, and saying they may unbalance the crank is silly. Unless the manufacturer does not balance the pulley when they make it, it wont make two bits a difference to the balance of the crank.

[Hikarispeed]

Originally posted by sykikchimp
there have also been questions as too the loss of the weight allowing the crank to vibrate more, and possibly shortening the life span of the engine.

Not really. Part of the job of the flywheel is to be a harmonic balancer.

[drifties151]

i didnt notice any power gains really, just makes the engine a little more rev happy.

[Dream240]

Okay, since you guys are having a bit of trouble deciding if they produce more power, check out this review.

http://www.importtuner.com/tech/0210it_powerpages/

As you can see they DO produce power, including making the car more "rev happy" As far as undrving the accessories, yes it does but not noticeably.

[old_s13]

Originally posted by Hikarispeed
Not really. Part of the job of the flywheel is to be a harmonic balancer.

Since when? When I get my OEM flywheels lightened, all they do is shave off a bunch of material and then balance the FLYWHEEL itself. The flywheel is separate from the motor. The motor itself must be balanced, but the flywheel does not balance the motor.

As for the crank pulley, I've had the UR pulley on my car for over 5 years with no problems.. I hit 170k on this SOHC KA and all I did was keep the rev's at redline during my canyon drives. I never ran into any problems with the UR pulley OR the lightened flywheel.

The pulley does free up some power, it is true.. but it does also sacrifice a bit of AC and alternator performance. It wasnt anything major, I just raised my idle to about 1000rpms.. the AC and alternator were fine from that point on.

- Mike

[Hikarispeed]

Originally posted by old_s13
Since when? When I get my OEM flywheels lightened, all they do is shave off a bunch of material and then balance the FLYWHEEL itself. The flywheel is separate from the motor. The motor itself must be balanced, but the flywheel does not balance the motor.

As for the crank pulley, I've had the UR pulley on my car for over 5 years with no problems.. I hit 170k on this SOHC KA and all I did was keep the rev's at redline during my canyon drives. I never ran into any problems with the UR pulley OR the lightened flywheel.

The pulley does free up some power, it is true.. but it does also sacrifice a bit of AC and alternator performance. It wasnt anything major, I just raised my idle to about 1000rpms.. the AC and alternator were fine from that point on.

- Mike

Sorry, harmonic balancer is a misnomer, but the flywheel does attenuate torsional vibrations which smooths power flow. BTW, the flywheel bolts on to crank.

[docrice]

honestly, i wouldn't let the underdriving scare you. even unorthodox says their pulleys will power a car with a 400w stereo, and some of their sponsored cars push like 800w with no trouble...and ac? mine works pretty good still in 95* weather, so i think its alright...

don't forget to change your front crank seal while you're in there, its worth $8 and a few minutes.

[orion::S14]

One thing to note:

Dunno about the UR pulley, but the ASP pulley does not underdrive the A/C - There's no need. If the A/C is on, you're not looking for max power. When it's off, the parasitic drag is close to nothing b/c the A/C pulley clutch is disengaged and free-wheeling.

ANyone know is the UR underdrives the A/C...?

Later - Brian

[russian]

woo, hold your horses, how come i never heard of the parasitic effect on alternator? (Stereo) i never heard of anything like this. how big is the loss, if its presesent, cant you just compensate it with capacitors???

[misnomer]

heheheh, Russian:

The alternator will spin faster or slower depending on power draw. A hefty stereo will draw more power, making the alternator spin faster, taking more power from the engine. You probably do not even notice it, though, the difference on your engine is relatively negligeable. Capacitors will not reduce it. All a capacitor does is stores up power during less "boomy" parts of the song so it can be discharged at more boomy parts. The same amount of power is required from the alternator. Essentially, the only reason to have capacitors is when you occaissionally hear your bass drop during harder hits. I don't like my stereo rattling the neighbors windows, so I don't have this problem :P