Underdrive pulleys [ merged 1/6/07]

[larryd]

Worth it or not? I'm thinking of going with the AEM tru-power pulley kit. Anyone used them?

 

[R-O-B]

If you get a crank pulley make sure it is a balancer also. Buschur's is the only one that I know of.
If it isn't a balancer you could run the risk of damage to the lower end.
Our engines are externally balanced.

 

[AntiRice]

what exactly is a pully kit and how does it work?

 

[Ludachris]

Pulleys are what your belts attach to. You can replace those pulleys with larger, lighter versions which should help your engine work more efficiently. The largest pulley is the crank pulley near the bottom of the engine block. R-O-B makes a good point... if you replace this pulley, it needs to have a balancer or else there's a good chance you'll damage your engine.

I think I'll hold off on those for a while.... they're not very cheap, don't have a big impact, and I have plenty of other mods I could spend my money on at this point.

 

[Silent2g]

i was told this years ago about underdrives

you spin the accessories slower, inturn to spin the water pump slower. which leads to running hotter.

this is very bad on turbo cars. or any forced inducted car.

me personally, i would never put them on a dsm or any of my own cars. they price per HP isn't there enough for me

maybe for a none driven show car i might think about

just a tip for ya man

 

[cmc]

Silent BOb, Imean 2G, speaks sense.

 

[Silent2g]

thank you jay

 

[xleRateGSX]

The idea is that it will be lighter and easier to spin. Where did you hear that it spun slower and is a bad investment? You just don't get enough HP for the cost. My .02

 

[Silent2g]

Originally posted by xleRateGSX
The idea is that it will be lighter and easier to spin. Where did you hear that it spun slower and is a bad investment? You just don't get enough HP for the cost. My .02

"underdrives"
smaller. makes accessories spin slower
overdrives
bigger, makes accessories spin faster


if you still question me. do some digging.


why do you think they come most of the time in sets
with the crank, alt, ps.

the crank pulley is smaller.
therefore everything else has to be smaller to keep the same rpm that it was before.

 

[xleRateGSX]

I am not questioning your opinion. That is just what I have been told.

 

[90TalonTsiAWD]

i have a friend who got a set of underdrives and loved them...till the next day when his 2g wouldnt ****ing start! the thing is, i guess 'clipses are notorious for weak alternators, so when you feed it less rpm, *especially when you try to run a system to it* it cant feed ure battery, and you dont go ANYWHERE.

MY DISCLAIMER: this is just a story relayed from a friend, i do not have a set and do not have a 2g, but i thought the story was still relevant.

 

[cmc]

: this is just a story relayed from a friend, i do not have a set and do not have a 2g, but i thought the story was still relevant.

Nice!

 

[jdmawd]

(ahem)

large pulleys spin slow

small pullies spin fast

the smaller the rotational diameter the faster it spins

underdrive pulleys are fine if you think you will have cooling issues don't do the water pump pulley. where do you guys get your information form big pulleys spin faster ()

 

[xleRateGSX]

, thanks jdmawd!

 

[IPT]

I have a set of DSM-Performance.com Underdrive pulleys and love them. They look great, the engine revs easier and I have not had any problems so far (have for a little over a month). They are the cheapest set on the market. They do not have the balancer. The pulley that does the underdrive is the crank pulley. YOu can purchase the kit with all of the pulleys except the crank pulley. My stock pulley was just a solid piece of cast steel. I thought the balance shafts inside the motor was for balance??

 

[Black95ESi]

I am running a set of AEM Pulleys, for the money, no, they're not worth it, they did however let my car rev a little faster and I noticed a slight power increase between 3 and 5 thousand, but I have had the problem of lettin' my RPM's drop too fast while having my stereo at full tilt when I was coming to a stop which in turn led to having my car sputter and almost stall, but it's hasn't stalled yet. There are definetly better mods to spend the money on, especially if it's a turbo.

 

[street sleeper]

has anyone installed an underdrive pulley, without a harmonic balancer , with stock internals(not bluprinted). If so have you had any problems resulting from this?

 

[street sleeper]

where are the wisemen?

 

[GRNDSM]

The wisemen are all exhasted from beating this topic to death .

For the record: I HATE THEM. You will have to do some searching to find out why

Leon
RR

 

[hekaboost]

i've used one for 50k miles w/ no problems and perfect compression! some people say its okay and others say its not...make up your mind cause you won't find any two people that agree!

 

[street sleeper]

thanks for the input, I'll look into it further

 

[doug]

I have one too and have experienced no problems. It's been on about 7 months now (about 15,000 miles). I've heard all the alleged stories about undamped pulleys, but I've also heard at least as many if not more stories about the stock pulley separating and causing a lot of engine damage. From all I've read and discussed the topic with people, the separating stock pulley seems more common than damage from a non-dampened pulley. For this reason I'll stay with the one piece design-- not because of the claimed HP gains. Maybe it'll blow my engine up, maybe it won't. Obviously my money is on the "won't".

 

[GRNDSM]

Doug,

The problem with your logic is that separating stock damper causes very clear damage right around 80-120k miles (or 5-8 years) at the moment of separation, where as undampened pulleys cause very slow, accumulative damage to your bearings, which might take 20-100k miles to surface. Then, you might just say: “I beat on this motor for that long, no wonder it went”. Most people would not connect the two.

But several reputable DSM shops have reported very strange wear on their bearings after using such pulleys and do not use them on ther own cars. Some that do use them, do so with understanding that they will be rebuilding their motor every 6 month anyway, due to running some insane amount of power.

I just replace stock pulley every 4-5 years… When I am forced to go with SFI approved pulley, I will get underdrive pulley with a damper.

Leon
RR

 

[doug]

I will definitely take your advice under consideration, Leon-- I respect your knowledge and opinions. Thanks, dude!

 

[sophat34]

ok, the engine is getting bored out right now and balanced shortly, I still need to get ahold of a set of pullies. is a harmonic dampener really needed? this is still going to be a street driven car and will rarely see a track. its a built 4g64/63 it will be fully balanced. also are under drive pullies worth it? any thoughts or opinions are helpfull