Damn can't seem to stop thinking about my car and get some sleep. Good thing too, I forgot to ask you guys this question. :D

I bought one of these here: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2455986081&category=38656

It's quite a bit smaller than stock and I talked to a mechanic I know that hooks me up... Well he's telling me that this may slow down my car because it's smaller in size and thus I would see a decrease due to lower RPM's or something. He confused me and I don't know exactly what he's talking about.

He went on to say the car was designed for the stock size and that the AC, and everything else connected to it will be affected negatively.

Um can someone please explain this one to me?

Like what are the benefits exactly I guess and if there are really negatives going with a smaller aluminium overdrive pulley.

This sucker was expensive, ran me $75 bucks and now I need to spend probably that much in belts alone and when I heard that from him, it was like a nightmare. :agh:

for every 1 pound of rotating mass=8pounds static weight. Every pound lost off the crank is equal to about 2.7whp gain.

The pulley is lighter so it will give you a bump in power. It is smaller which means it is easier to drive, which translates to being easier to drive all the other pulleys on your engine.

The accessories are driven slower, but you will not notice anything different unless you have alot of stero equipment or a very large draw on the electrical system.

Hope that helped a bit.

UDP is one of the best power for the dollar mods on an N/T.

How do these not fit on to your car?
Let me know.. because i was planning on buying these.

As long as you don't have a turbo model 1998 Eclipse, it will fit.

ashah000, what I meant by not fitting is they require new belts which i didn't have with me when I wanted to replace the UDP. These are the belts sizes you'll need: Alternator #K040320 / AC & Power Steering #K050490

89Turbo944, wow a 2.7whp increase for every pount shaved off? So it's it's a 8lb difference, I may see 21.6whp increase? :D I would of been happy with 5. :)

I wonder what kind of a hit is it to the electrial system though? I do have a $10,000 stereo setup in this car, but it's not high wattage, just sound quality.

I do have a yellow Optima battery, and I'm hoping it's powerful enough that I won't notice any difference.

But to be on the safe side, I'll kinda list what I have quickly and you guys can maybe tell me if I should be concerned about having less power for electrial.

Eclipse 8053 deck
8", 5.5", tweeker 3-way MBQuart speaker setup
Phoenix Gold SX6600 amp - modded for more power by Phoenix Gold engineers
6X 10" JL subs
capactor

and in a nutshell that's pretty much it. Appreciate the help! :)

The numbers quoted (2.7 whp etc) were either specific to a particular setup, pulled out of someones ass, or a wannabe engineer's wet dream. There is no way to can estimate it down to one decimal place. And it will vary with each car. It will more likely be expressed as a percentage than a hp per pound figure. Also, the amount of gain will vary with not only the weight reduction but the weight reduction relative to its moment of inertia, or distance from the center of the shafts rotation.

You certainly will not see a 21 HP increase at the wheels. ;)

The numbers quoted (2.7 whp etc) were either specific to a particular setup, pulled out of someones ass, or a wannabe engineer's wet dream. There is no way to can estimate it down to one decimal place. And it will vary with each car. It will more likely be expressed as a percentage than a hp per pound figure. Also, the amount of gain will vary with not only the weight reduction but the weight reduction relative to its moment of inertia, or distance from the center of the shafts rotation.

You certainly will not see a 21 HP increase at the wheels. ;)

Hehe yeah I figured it wouldn't be anywhere close to that. But um I'm worried about the electrial power decrease - I guess thats what you'd call it. Because my car right now is having some alternator noise and I had to decrease the gains on the amp to quiet it down. I was thinking the alternator could be stressed too much already. Or I was told from Cartoys that it could be a interference from something else (there used to be a little more equipment, tons of wires everywhere). So I dunno just wondering what your thoughts would be on it.

Underdrive pulleys are just stupid to add, enough said. The stock pulley is so big because it absorbs vibrations. So if you want your crank to crack, get one.

In that case I would say the few HP you are going to free up are not worth the trouble. DSM alternators arent huge to start with (65 amp I believe), and it seems your stereo is an important part of your car. I wouldnt risk it. On a brighet note though there is a larger alternator that physically bolts right in, be needs some wiring (different connectors I believe) from certain galants, 95 amps if I'm not mistaken. Thats a nice increase, and any good stereo shop should be able to wire it in. Might be worth looking into, especially if your alternator shits the bed... Either way, good luck with it.

Underdrive pulleys are just stupid to add, enough said. The stock pulley is so big because it absorbs vibrations. So if you want your crank to crack, get one.

Yeah the mechanic said something around these lines...

In that case I would say the few HP you are going to free up are not worth the trouble. DSM alternators arent huge to start with (65 amp I believe), and it seems your stereo is an important part of your car. I wouldnt risk it. On a brighet note though there is a larger alternator that physically bolts right in, be needs some wiring (different connectors I believe) from certain galants, 95 amps if I'm not mistaken. Thats a nice increase, and any good stereo shop should be able to wire it in. Might be worth looking into, especially if your alternator shits the bed... Either way, good luck with it.

Hmm interesting that larger alternator sounds like something I may just need.

Would you happen to know where I may beable to pick one up? Checked ebay and dsmtuners and didn't notice anything.

Thanks!

The stock pulley absorbs harmonic vibrations because it includes a harmonic damper (the rubber section in the center). Not having one can contribute to crankwalk (as documented by a respected BMW tuner), but since this was an NT I didnt want to go into it. Just another reason to sell that on ebay, the same way you found it :D

The stock pulley absorbs harmonic vibrations because it includes a harmonic damper (the rubber section in the center). Not having one can contribute to crankwalk (as documented by a respected BMW tuner), but since this was an NT I didnt want to go into it. Just another reason to sell that on ebay, the same way you found it :D

I see thanks for explaining that a bit.

Without adding a turbo kit or a nos bottle, I really dunno how to add more power. I just want a little bit more punch.

Maybe you or someone else can suggest also quickly what other things I may buy to speed up the car but not affect the engine or stereo negatively. :D

mods I have so far:

4-1 headers
2.5" catback
NGK Iridium IX spark plugs
larger spark plug wires
AEM V2 CAI

And I believe cam gears are not recommend that much due to their wear on the engine components...?

Would you say getting light weight wheel (~15lb) would help me out here in the speed department?

Also planning on buying a short shifter, maybe that will help a bit too.

The numbers quoted (2.7 whp etc) were either specific to a particular setup, pulled out of someones ass, or a wannabe engineer's wet dream. There is no way to can estimate it down to one decimal place. And it will vary with each car. It will more likely be expressed as a percentage than a hp per pound figure. Also, the amount of gain will vary with not only the weight reduction but the weight reduction relative to its moment of inertia, or distance from the center of the shafts rotation.

You certainly will not see a 21 HP increase at the wheels. ;)


Time to eat your words.

Modifier Mag, Issue 4/30, April 2003. Page 61 Paragraph 3.
and i quote "Every pound lost off the cranksahft averages out to be 2.7whp gain."

This was tested on a 2G Eagle Talon. All the results were from dyno testing. All be it, they used the Unorthadox Racing Underdrive pulley Ultra SS kit. Which includes all accessorie pulleys. But the quote still applys.

On my 300ZX i picked up 23whp, and the kit claims to give 25whp. So i think it is fairly accurate.

Time to eat your words.

Modifier Mag, Issue 4/30, April 2003. Page 61 Paragraph 3.
and i quote "Every pound lost off the cranksahft averages out to be 2.7whp gain."

This was tested on a 2G Eagle Talon. All the results were from dyno testing. All be it, they used the Unorthadox Racing Underdrive pulley Ultra SS kit. Which includes all accessorie pulleys. But the quote still applys.

On my 300ZX i picked up 23whp, and the kit claims to give 25whp. So i think it is fairly accurate.

Now you gave me the idea of trying out this UDP again. :D

Well, i dont know if it would be the best idea to do it on the DSM seeing as they tend to develop "crankwalk". The deletion of the vibration dampiner may lead to accelerated crankshaft end play. (not a good thing)

But many people have done it and had no problem. If you do decide to go with the UDP then measure your cankshaft endplay before and a month or so after. See if it has increased. If it has remove the pulley and sell it. :D

Goof luck

did u notice u said "AVERAGE" which is a calculation based on various cars meaning some cars may have gained more then 2.7 while others under. so hes not actually "eating" his words.

Did you read the article???

I dont think you did. I quote again." Since the stock crank pulley weighs a hefty 6lbs and the UR crank pulley weighs only 1.1lbs, this translates into 39lbs of dead weight or a 13whp increase"

Now doing that math in my head (6lbs-1.1lbs=4.9lbs)(4.9lbs x 2.7=13.xx) So that is the gain. They gained 2.7whp with that pulley on the crank.

The calculation was based on this car not on a variety of cars. Yes he is, i did not pull these figures out of my ass. I have then in documented text.

No offense Kevin, just making a point. Your still the god of DSM's:)

Please find tha article and read it next time before you tell someone what it means. :D

This was tested on a 2G Eagle Talon. All the results were from dyno testing. All be it, they used the Unorthadox Racing Underdrive pulley Ultra SS kit. Which includes all accessorie pulleys. But the quote still applys.

That means it probably includes pulleys that are smaller diameter than stock, reducing power loss of spinning the pulleys. Underdrive is still a bad idea unless you add a harmonic damper. I have read the 2 horse power per pound thing, but the dynos I have seen pre balance shafts, and post never amounts to even close what it should be. Using the math they use, it should be like a 35 something power gain, but it just doesn't work out. Underdrive is just a bad idea, and thats really the bottom line.

Yes it includes one underdrive pulley and accessorie pulleys. The accesorie pullyes are the OEM size, but lightened.

Using the mathe that i used above you reach the claimed whp rating.

But yes the underdrive pulley for the DSM is a bad idea. Works good on my Z tho.

Time to eat your words.

Are you joking? I'm sure this is the moment you have been waiting for, but I wont be eating any words on this topic. Trusting a magazine was your first mistake. Taking that tone of voice with me was your second.

Well there is no tone of voice expressed during a conversation using letters. Bu ti was partly joking. From what i have gathered from the time i have been posting here you age the god of the DSM world in this forum.

I was just posting infor that i had. But sorry if it came off the wrong way. Didnt mean for it to be like that. My bad. Should have put the usual j/p.

Holy shit, theres a second page here...

Well then no offense taken. ;) I'm just used to people looking to jam it up my ass any chance they get.

I understand this was in a magazine, but they are really the last people to trust. The companies they write the articles and reviews on pay thier bills through advertising. The dyno man can fudge the parameters to alter the gains seen. If a set of pulleys really saved that much power, they would be selling a lot more of them. And if taking out 1 pound 4" from the crank was good for 2.7 hp, taking out the same pound from the flywheel ~8" from the crank would have double the effect. And thats just not the case. Seems like an exageration to me.

It most likley is but i just posted what they said. I do not have personal experance with a DSM and UD pulley. But i figured they were one of the more trustable tuner mags. Seem to have pretty accurate info on new products and such.

Once again no offense was ment by what i said. I feel bad, I insulted the god of DSM :( Glad to see you dont take it to heavily.

Good on ya mate

Hey, its just the internet. Cant take things to seriously. :D And I'm no God by any stretch of teh imagination, and I'm often wrong just like everyone else. ;)

No you are the DSM god,

New sig for Kevin, www.automotiveforums.com DSM GOD

Just cause i said so.

I'm just used to people looking to jam it up my ass any chance they get.

O.o

no it goes form this ()o() to this ()O(). Not from bigger to smaller. Only in a perfect world.
:evillol: :devil: :greddy2: :gay:

I'm confused... you guys are saying that UDP are just a bad idea for DSM's.
Well, i dont know if it would be the best idea to do it on the DSM seeing as they tend to develop "crankwalk". The deletion of the vibration dampiner may lead to accelerated crankshaft end play. (not a good thing)

I thought that a NT can't get crankwalk... or was i wrong.

So if a NT can't get crankwalk what is wrong with getting UDP
I dont think the NT has a harmonic dampener to start with.
Sorry if i sound like a tard... but i am confused. :eek7:

first off any motor by any company can develop CW. CW is a condition that is rare, it occurs more often in forced induction vehicles because the engine is under more stress. DSM's assembled from july of 92 on have seven bolt motors. the 7-bolt has a design that is more susceptable to CW. it is still not a common thing CW an engine.

secondly, i do not know of a engine that is stock from the factory that doesnt have a harmonic balancer on the crankshaft pulley. they absorb the energy that tries to push the crank out of circular rotation when the pistons fire. there fore extending the life of the engine. if you remove the harmonic balancer from an engine you can get some HP gains but now you dont have anything there to absorb the energy from the crankshaft, there for the only place for the energy to go is into the crank. this can lead to a cracked crank and CW. this also puts a large amount of stress on a lot of other moving parts inside the engine. therefor shortening the life of the engine. in my opinion if you were building a track only car i would say go for it. put the UD pulley on. but since this is your daily driver i wouldn't do it. not worth the headache. hope this helps. :thumbsup:

i got a full pulley kit oin my 92 eclipse they say it can add about 15hp about 1.7 hp per pound taken off the crank. and for accesorie powewr mine only did the underdrive on the a.c. so the alternatror or anything else wasnt affected. and belts costed me about 20 dollars tops.

I was just searching around, and i found these... http://www.machv.com/busracunpul.html they are UDP with a harmonic dampaner these are just for a gst/x but they are $350 :banghead:

And this site explains pretty much everything about UDP and harmonic dampaners. http://www.machv.com/tip11cranpul.html