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?

 

[weegee411]

as far as I see its the same risk. and I have an idea that the few ppl who have had problems with it dont check oil or run good oil or manage their car good. and also Im at high altitude so noticing differences are very apparent. so what is your guys' ideas? just change the accessories?

 

[dsm8883]

is your profile up to date?

 

[LiquidX]

Changing your oil every day won't save wear on the bearings or the vibrations on the crank. I'd like to know where you heard 30hp for a swapped pulley.

 

[T is for TURBO]

Okay, It's clear you don't want to listen to any of us. But I'm bored right now. So, here it goes. First of all, altitude has NOTHING to do with the crank balance. Second of all, you could have the best oil in the world, and and unbalanced crank is going to cause premature wear, there is no way around it. And third, don't end your sentence with the word "good", okay?

 

[JusMX141]

wait ok so if I have less weight on one side of the crank and its not balanced evenly it will wear more of the internals on the passenger side?

It has nothing to do with one side of the crank weighing more or less....obviously the stock flywheel outweighs the stock crank pulley hands down. The concern here is that the stock crank pulley is rubber-dampened to absorb crankshaft vibration as our engines are not internally-balanced from the factory. By taking away the engine's only way of correcting vibration without actually balancing the entire rotating assembly would be a bad idea.

I'm sure more than a couple ppl have installed it and have seen no problems, is it like a random problem like crankwalk which you always hear about but hardly ever actually see?

Would you want to be one of the guys who installed a crank pulley and had their low end explode in 1000 miles or less? Would it then be worth the .002hp gain and great eBay pricing?

 

[weegee411]

No my profile isn't fully updated there are plenty of more upgrades on it.
I never said changing your oil everyday would help save wear. Im talking about the guys that use the same oil for 15xxx miles till the oil has broken down to almost a non lubricant state and is destroying their engine.
Yeah Im not listening to some of you because your not answering the question I asked. Hopefully you can actually read it and help instead of what your doing.
Either way rubber still vibrates to a point. and a crank pulley s a great difference, I've had other cars that I have installed a crank pulley on which made a noticeable difference.

 

[DSM1G90]

Has anyone installed an Ebay underdrive and how good does the car perform after being installed? Or is unorthodox the way to go?

I'll chime in and answer "no, I haven't tried these underdrive pulleys-thought about it once but declined the idea since I'm a DD and want to keep my motor intact."

Yet, if you're doing drag or weekend BLVD street racing, it'd be fine for that being that it does reduces the turning torque for like the alternator and you're not running it that long. But if you're going to do a lot of DD, get a car that is stock with parts and equipment designated for DD usage - leave the unorthodox vehicle for the track or strip.

I've seen cranks snapped in half due to failed harmonic balancers on those big diesel engines. Not fun when the piston downward travel on compression stroke is actually twisting the crank and that balancer absorbs the return twist of the crank fails to do what it needs to do.

We all have to realize that the crank really isn't turning in a smooth rotation. It's actually being snapped forward per each power stroke of the piston. And each of these 'power snaps' actually snaps the crank forward before the flywheel catches up with the rotation..and you get this vibration. If there wasn't anything to absorb these vibrations, these harmonic vibrations caused by this continual 'snapping' will actually go from damaging crank bearings to shattering cranks.

Even if there is some vibration with harmonic balancers on, at least some of that damaging vibrations are removed to ensure longer life on the crank.

Have fun - DSM

 

[Spoolin18]

It has nothing to do with one side of the crank weighing more or less....obviously the stock flywheel outweighs the stock crank pulley hands down. The concern here is that the stock crank pulley is rubber-dampened to absorb crankshaft vibration as our engines are not internally-balanced from the factory. By taking away the engine's only way of correcting vibration without actually balancing the entire rotating assembly would be a bad idea.



Would you want to be one of the guys who installed a crank pulley and had their low end explode in 1000 miles or less? Would it then be worth the .002hp gain and great eBay pricing?

+1
Yea, what he said.

 

[nlzn]

Question: what's the point of posting a thread asking for advice when it's apparent you've already made up your mind?

Every single reply here has told you it's not a good idea (including myself). That's really all we can do.

I don't understand your logic, especially of the head/top end versus the rotational assembly. First off the head is way cheaper to replace than the bottom end. If done right (i.e. balanced and machined it will cost a pretty penny).
Second, what does altitude have to do with anything? Sure, the air is less dense but how does that effect the integrity of your bottom end, much less balancing?

It's not worth arguing because you've made up your mind. Many people have warned you that not only is this a waste of money, it has a huge risk of costing you a lot more money in the end.

In the end we're just trying to help. But who knows, maybe you'll be the exception to the underdrive failures.

Goodluck.

 

[snowborder714]

He did not come here asking for advice. If you'd read the first post fully, you'd see that.

He came in here asking if anyone else has run one of them. He realizes it's not a good idea, yet is doing it anyway (this is the part I don't get).

Maybe he doesn't have the money for a good dampener? Maybe he wants more bling on his engine? Maybe he wants to underpower his alternator, water pump, power steering pump, etc.?

 

[H82lose91]

I havent personally ran on of these for a few reasons but have seen a couple. The ones i saw looked more like cast piece instead of machined billet. That being said, the two that i saw both had cracks and damage to the where the belt ride in them. The outter alignment ribs if you will.

My first DSM i installed an Unorthodox underdrive crank pulley. Ran it for 50k miles. And saw no signs of bearing damage due to running it. Was i lucky, probably. I run a stocker on my current ride only because it hasnt failed yet. Once it does ill probably stay with stock since i saw nor felt any gains with the other pulley except for the fact that it didnt separate.

 

[ClipseAPG]

Yeah and boosting more actually goes through the head and piping etc so theres more risk there. Im installing the underdrive either way. It makes more sense to install the underdrive system and see 30 more horses and blow a bottom end then boost 5 more lbs and n risk head, turbo, etc. I was just wondering who's installed an ebay one and how good they ar balanced

I did a search and saw one story and other people saying they noticed a gain and havent had problems with installing the underdrive and no problems with crank on a 2g

Now I'll be honest and start off by saying that I have an ebay lightweight aluminum crank pulley. It came with the car and at first I thought "cool, extra hp" but after reading everything about the horror stories of not using harmonic dampeners I have wanted to go back. Now I haven't had any problems with mine (that I know of) (knock on wood) but I recommend that if you want to stay on the safe side, don't do it. Unless it's a track car and not much else, In which case you probably expect part failure eventually, and a messed up crank is all the reason to build your block !

 

[SonySlave]

Our cars already have enough issues with the electrical charging system and people are wanting to put UNDERDRIVE pullies on their cars? That just sounds retarded to me (no offense anyone ). Yeah lets turn the alternator even SLOWER! I just can't see the benefits.

I just did a little research and found some pics of crankshafts that had broken in half. Screw that!

 

[LV-DSM]

That's enough information for me to decide to remove my Unorthadox. Fortunately I haven't run my motor more than 5 minutes with it installed. I bought it when my original seperated and got a good deal, not realizing that it could do more harm than good. After reading this thread I would highly recommend the OP do the same. But, if for some reason you are still interested, PM me. It's shinny and blue.

 

[FMFGSX]

Here's some pictures.
http://www.dsmtuners.com/forums/cylinder-head-short-block/268533-broken-crankshaft.html

 

[DSM1G90]

....Yea, when I saw a six inch journal snapped on that truck diesel motor's crank(big ol' straight six motor)-and right in the middle-caused due to a harmonic balancer fail, I always wonder what that rubber filled damper device that sat behind the crank pulley on Chev Big Block V8's were....

-DSM

 

[weegee411]

Here's some pictures.
http://www.dsmtuners.com/forums/cylinder-head-short-block/268533-broken-crankshaft.html

did you also read that it was a machined crankshaft (used) You cant point that to the dampener when your using a a crankshaft that has been shaved to s smaller dimension making it more brittle.

 

[FMFGSX]

http://www.dsmtuners.com/forums/1513989-post386.html
More pictures...

 

[LiquidX]

did you also read that it was a machined crankshaft (used) You cant point that to the dampener when your using a a crankshaft that has been shaved to s smaller dimension making it more brittle.

When they shave a crank, they are only shaving off THOUSANDTHS to remove any scorring.

 

[Hayabusa9900]

so is there underdrive pulleys that use the stock balancer????

 

[KRYPYONIGHT]

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

I know this was from years ago & I'm hoping this guy didn't know anything about our engines at the time. If he had, he'd know that putting on a set of underdrives bullies would in no way affect how the motor is kept cool, the water pump is turned by the timing belt, not an external accessory drive belt.

 

[GRNDSM]

On 4g63, water pump is spun by alnertnator belt, so underdrive puller will slow it down. He was 100% correct in this aspect of his argument.

However, you could argue that water pump already spins faster than it needs to and underdrive pulley is not doing any harm to the cooling system.

But if you are going to bump a five year old thread to "correct it", make sure you are correct.