NewYorkTypeR

What purpose do these serve and what type of gains should I see. Also a price range I should be looking at. Thanks for the help. Hope this isn't a stupid question

MaddMatt

Underdrive pulleys serve 2 purposes: 1) They underdrive the accessories a little by using a smaller diameter crank and slightly larger accessory pulleys. This means the accessories turn less and rob less power. 2) They are lighter. This is key. Underdrive pulleys are made of alluminum vs. the steel of the stock pulleys. Since it's on the crank (like a flywheel) using underdrive pulleys is like lightening the flywheel. For a 2 pully set, expect in the neighborhood of ~5-6 wheel hp. However, it has a much larger effect because it's accross the entire rpm range, not just one area like a header or intake. I spent ~$200 for a 2 pulley set from UR for my SE-R.

Matt

eviladam

you are aware that replacing the crank pulley can quickly destroy bearings right?

MaddMatt

I've never heard of this. I've only had mine on for a few thousand miles, but considering that I've autocrossed, driven on track, and drag raced with them, they are a few thousand hard miles. I have no complaints or problems with anything. If you have access to any info that describes how the bearings fail after replacing the crank pulley, please post it. I'm interested in reading it.

Matt


[Modified by MaddMatt, 12:24 PM 6/26/2001]

D

not this debate again... there's a huge thread on here or endyn's board... pics, and a lot of disagreements. lemme see if i can find it.
http://ferrari.colowatch.com/php/sho...w=&sb=&o=&vc=1

up to you...



[Modified by D, 3:53 PM 6/26/2001]

TheShad0w

I've heard of the issue, im not quite understanding the problem though.., i understand the dampening affect need on your crank for the resination, but I dont see why it would cause problems on n/a engines, unless you are pulling ungodly power, and didnt prep your crank with the proper harmonic dampening weights anyways.

D

resination?

MaddMatt

My sources tell me my SE-R crank is internally balanced, so there's no issue (for me anyway) about bearings failing prematurely. I have to assume Honda does the same internal balancing with their engines? If so, I can't see why bearing failure would be a problem. But stanger things have happened, I guess....

In any event, I think underdrive pulleys are a great bang for the buck mod.

TheShad0w

Yeah, natural noise "resinating through metal"

Harmonic distortion and vibrations can tear apart unbalanced engines that arnt internally ballanced.

Jared

Do not use an UR crank pulley. My friend's Civic drag car went through three oil pumps in as many weeks because of one. Replaced it, no problems over 3 months so far.
later,
Jared

TheShad0w

what does that have to do with your oil pump?

Perhaps it had to do he was running allot of oil through a stock oil pump gear?

Also, if you do ever plan on creating enough vibrations from your engine to demolish your crank bearing and/or other internals, they do make special harmonic dampiners for your crank to create a less damaging affect from this shaking that can damage your engine.


[Modified by TheShad0w, 2:16 AM 6/27/2001]