Underdrive Pulley

[croc-note]

I was checking on E-Bay for fun and I saw some lightweight Underdrive pulley and that say 7-10 more HP (OK i know on E-Bay all give 7-10Hp check SRI 8-15hp lol)
How can a pulley give some hp (maybe 1 or 2 max) and is this worth to change the OEM one for a lightweight one from E-Bay ???

[Leung]

maybe a marketing gimmick? you know something to get your attention.

actually i don't even know what an underdrive pulley is.

[deevergote]

Underdrive pulleys, especially the crank pulley (usually lightweight and smaller diameter) DO increase power. Alternator and Power Steering pulleys are also made, but they don't do as much.

However, ebay pulleys, compared to more expensive ones like Unorthodox Racing, may be dangerous. To put a potentially unbalanced pulley on, you run the risk of seriously damaging your engine. If you're looking to get an underdrive pulley, I would spend the money for Unorthodox Racing. I've been running one on my H22 for over 2 years with absolutely no problems. Some people feel that they can cause damage, but my experience says otherwise.

[InvaderTrax]

Had a thread just like this last week. Hopefully it'll answer all your questions

http://www.cb7tuner.com/vbb/showthread.php?t=53217

[dan21]

i actualy just got one last week its a difference nothing huge

[deevergote]

Even a 10hp gain isn't something you're really going to notice. If you're REALLY in tune with your car, maybe... but most of it will be in your imagination.

[kslice88]

a lighter pulley can gain u hp cuz its less weight it has to turn when the crank turns, thats why people with "race" or "track" cars will run the least amount of acessories or will have a shut off to their alternator, ur alternator will rob u off like 5hp or more in some cases believe it or not

[AccordWarrior]

a lighter pulley can gain u hp cuz its less weight it has to turn when the crank turns, thats why people with "race" or "track" cars will run the least amount of acessories or will have a shut off to their alternator, ur alternator will rob u off like 5hp or more in some cases believe it or not

But what works in a track car doesn't always work in a street car. I strongly feel risking the motor for a 2-5 hp gain isn't worth it. Most lightweight pulley applications are on race cars, who's motors only have to last a few hours, not thousands of miles like our street cars.

[accrdpower]

underdrive pullies will def get u power upwards of 10-15hp with the entire set of pullies(depending on condition of engine) the only thing u want to worry bout it getting a good lightweight pulley like Unorthodox Racing (UR). there is no eveidence or at least no credible evidence to support that underdrive pullies damage cars.....its the fools that beat the cars after getting the pullies thaty ruin their cars, not the pullies themselves. just bc u have a lightweight pulley doesn't mean u can rev it to 7k. i've been running my UR pullies for at least 1 year now or over 35k miles and there are NO issues.

[NAiL05]

Yessir pulleys are supposed to lessen parasitic drag caused by rotating components. You will rev free'er you wont feel the power increase as I didnt but the engine revs free'er and it DOES NOT mean you can rev to 7k as mentioned.

[AccordWarrior]

underdrive pullies will def get u power upwards of 10-15hp with the entire set of pullies(depending on condition of engine) the only thing u want to worry bout it getting a good lightweight pulley like Unorthodox Racing (UR).

There's no way you're getting that much power on a 4cyl with those pulleys. You might see maybe 6-7 crank, but 10-15?...then how much do you get off an intake? 20?

You could debate the underdrive pulley situation til you're blue in the face. I've read enough testimonials about people screwing up their oiling systems with underdrives to decide its just not worth it to risk it, and that's the advice that I give people. If you disagree, cool, but there's enough credible evidence to show that you can have issues running an underdrive...but if you know that and run it anyways, more power to you, maybe you will be one of the lucky people that don't have issues.

If I was going underdrive, I'd go fluidampr, because they are built correctly for our motors.

[moebius]

Agreed - If you *must* go underdrive, use a properly damped pully - like the FluidDampr.

Bottom line, Unless you are racing (ie sustains 6k rpm +) , underdrives simply are not worth it, and even then, it is better to just remove the a/c, p/s, or other accesorice than under-driving it.

Underdrives:
1. do NOT reduce engine wear (unless properly damped, but even then it is no improvement over a stock damped pulley)
2. they do not increase power (they reduce parasitic losses at high rpms),
3. are ricer bling (what more reason do you need to avoid them???)
4. undamped pulleys *do* damage unbalanced engines (ie, most 4 cycl engines!)

anyway...

[kslice88]

the "power" gain u will get isnt worth what ur gonna pay for the pulleys, unless ur gonna build ur motor, u wont feel the 6-7 or even 10 hp that u might get. thata just what i think. its ur car

[killrmack]

If you you do deside to get some make shure there quality my cousin bought a civic and it cept eatin belts becase the pully wasnt made well it had a "slight wobble" as we were told

[accrdpower]

yes some car have messed up their oil systems like i think it was fast93accrd or someone on cb7tuner but when u build a powerful engine and don't upgrade the oil system then u deserve to have the stock crappy oil pump blow on ya. and the engines are internaly balanced. and yes we each have our own experiences. but no one i have seen/helped install underdrive pullies have had any issues and i have helped too many. i respect that some are hesitant to use them and thats fine by me. but if u do your research b4 hand on the topic it clearly states that some oil pumps need to be upgraded bc of the low grade material used by the factory. but it's the best mod i have done so far with the best gains. and how is something that is meant for power/increase efficiency RICE????? whoever said that statement needs to seriously rethink that bc he called everyone on this forum a ricer bc they modify their engines to create more power/efficiency. lol wow

btw reading testimonials means jack. it actual experience that really counts. just my opinion. many people base their statements on everything but first hand experience and will die defending their point even though they know nothing personaly about it. i am not saying you are basing ur opinion on bs accordwarrior bc i know ur pretty knowledgable but don't base what u say on 2nd,3rd,4th hand knowledge. use your own. ur smart, i know u got it.