You sure that its "bigger" than stock? I dont see how bigger would help, considering the fact that a bigger pulley would require your engine to work harder to turn (think torque equation, backwards, as well as an increase in rotational inertia)

I have an underdrive pulley on my eclipse. It's considerably smaller (about 1/3 the size) and MUCH lighter than stock (7lbs as supposed to ~20lbs). Effects- rev up easier and faster, accessories dont drain engine power, and ~8 HP to the wheels.

For my car, this was a GREAT mod to do. There is a lot of potential for damage, but I've never had any real problems... and I installed it myself. I did need to change out the belts (the ones they sent with it were crap), they were squeaking pretty bad. Some others I know have had dimming lights when they were at a stoplight, but a little rev quickly took care of it.

Many posts on this board dont seem to like the idea. I'm not aware of the actual level of benefit it will provide for an H22, but its definitley not a modification that you should specifically avoid. If done right, it'll last you 30k+ miles... like mine has already.

 

And the stock pulleys will last you 200k. With no dimming lights.

 

It's a trade-off. I have the pulleys and my lights dim but only at idle. I feel that I had a slight increase in power. They dress the engine bay nicely too. I still wouldn't make the jump for a crank pulley though.

 

http://www.pacarsearch.com/stealth/udp.htm

Here's a good explanation of crank pulleys. Even though it isn't on ludes it works the same. There's a lot of debate about them but basically it's saying it COULD fry your bearings due to torsional vibration not that it will.

 

Most of the power you pick up on underdrive pullies comes from the crank pulley. The problem with some aftermarket pulley sets, especially on Honda engines is that the new crank pulley doesn't use the ever important torsional vibration dampener. So make sure you get a set that does not require the stock dampener to be removed and you shouldn't have any problems. Another thing to consider is how the pullies achieve the added power. Underdrive pullies gain power in two ways. They are either a smaller diameter, which sucks, because your accessories like ps, and your alternator don't work as well. The second way is by weight savings. The lighter they are the easier they are to spin and they create less parasitic drag on the engine. I've had experience with both types and I would say if you can find a set that keeps the same pulley diameters as stock, but are much lighther, then that is the way to go. you'll pick up some power and everything will work the same. Unorthodox Racing makes lightweight pullies that work well and maintain stock diameters, so your lights won't dim and your battery will get a full charge from the alternator etc. Sorry for the novel

 

do you know of anyone that makes the crank pulley with a vibration dampener built in? Unorthodox doesn't.

 

I'll do some checking and get back to you

 

Hey Nero,

I did some checking and I don't think there are any kits that actually come with a new dampener. The difference in kits is that some of them can be installed without removing the stock dampener and some of them require you to remove the dampener in order to install the pulley. You definitely do not want a crank pulley that requires you to remove the dampener. That's where all the trouble comes from. AEM makes kits that retain the stock dampener, but make sure cuz I think they also have kits that eliminate the dampener as well

 

the 4th generation preludes have internal balancing shafts to help stop engine vibrations, unorthodox racing pulleys would be a very good choice since they make 90% of their power from weight savings 2.7 hp per lb