# Light weight pulleys vs under drive pully



## dogdog (Jul 26, 2007)

Hi,
I am thinking of buying a set of under drive pulleys. 
Saw the 2 Light weight pulleys and under drive pulleys. 
Didn't know what is the advantage / disadvantage between the two.... just heard some where that that AC is not pulling that strong in under drive pulleys.
Does anyone have a link that describe the difference between the two. 
This is to be install on a Jetta 8V 2.0 AEG daily driver.


----------



## tdogg74 (Mar 1, 2002)

*FV-QR*

http://gruvenparts.com/website...d=310
Dont go with under drive pulleys...not worth it.


----------



## godoveryou (Apr 1, 2007)

*Re: FV-QR (tdogg74)*

I respectfully disagree tdogg. I don't know what it's not worth, but I have yet to see where in *most* of the lower 48 states a negative impact has been generated by their use. Since the early 80's car makers have used their engines in corp. or global platforms. They are used through most of the country by enthusiasts because the OEM pulley is typically a generic answer to non-destination specific engineering. Areas like Arizona, I can understand the need for the OEM sized pulley to drive the water pump at high speeds at idle. Same with over driving the alt. at idle in Alaska. But that is why it is OEM. The Original manufacturer knew that they would be selling cars there, so instead of making multiple different castings, they just use one cheaper casting across the country. It simplfies the manufacturing and distribution process. 
Underdriving an accessory does not shorten it's life span. I used the search function of this board to try to determine where this slice of misinformation was generated, but I couldn't find the origin. I'd love to know how it is thought that accessories would be damaged. The lower speed of rotation is actually GOOD for the bearings in each accessory. Less heat is generated by not spinning the accessories faster than they have to be. The Alt produces full charge at VERY low RPM's. The water pump cools very effectively at almost any off-idle speed. The power steering is constantly generating pressure, and the AC doesn't really work well in our cars at idle anyways. Where's the loss?
Gruvenparts was nice enough to send me a PM in which they clearly stated that it was *Only an Opinion* that accessory life was decreased, but nobody knows how or why. On the other hand, I can clearly point to how and why a longer service life out of the accessories may be expected by not driving them faster than required. I can even point out the part in the accessory that has less stress placed on it. 
In an engine that see's endurance race duty, normally only the water pump and alt. are present in the system anyways, so no, they typically aren't found there. However, there is a large difference between the stress and demands of an endurance race engine and a daily driver. I could understand the arguement that they shouldn't be on a daily driver because of reliability concerns, but I'm going to need to see what the concern is first.
....nobody seems to know why it would hurt an engine, they only seen to know that they've been told it would. 
Obviously, this post is NOT directed at you Tdog, I only placed your name there because I was trying to express respect for you.










_Modified by godoveryou at 2:14 PM 12-2-2008_


----------



## ghoastoflyle (Jan 21, 2003)

*godoveryou* That has got to be the best rebuttal on the subject, I've read so far. Clear easy to follow and logical thoughts. I don't know the answer my self but just wanted to say thanks for adding something I think everyone could marinate on, if not it provides for a good argument. 
I'd love to see the results under driving Vs. Weight reduction. If similar results are proven why not just reduce rotating mass to be on the safe side.


----------



## JBETZ (Feb 17, 2000)

I've never liked the under drive pulleys mainly due to the VW's being so finicky when it comes to voltage and power issues and most guys are running stereos system to boot. I also don't like to run lower boost when turning a supercharger. Just another point here. 
Here is our version








http://www.bahnbrenner.com/vw_...ey_8V


----------



## Jay-Bee (Sep 22, 2007)

*FV-QR*

^ what's the weight difference on the BBM piece?


----------



## JBETZ (Feb 17, 2000)

*Re: FV-QR (Jay-Bee)*


_Quote, originally posted by *Jay-Bee* »_^ what's the weight difference on the BBM piece?

I think it is close to a couple of pounds. I need to get out there and weigh it again.
We also have this one
http://www.bahnbrenner.com/vw_...V_20V


----------



## godoveryou (Apr 1, 2007)

*Re: (ghoastoflyle)*

Thank you Ghoast.
As far as firm data to support one over the other, I think it will be a hard fight to prove, even over a stock pulley. Here is the problem:
When driving under normal conditions, the engine is only under the load of the associated drivetrain, the weight of the vehicle, and the conditions under which the vehicle is operating (ie, tire pressure, width, pavement, wind, etc). A dyno places load on the tires to calculated the force required and generated to spin the drum. Not all dyno's use the same brake or force application system and calculations, but they all basically operate on that basis. It's not an accurate gauge of real world performance. A dyno is actually much more stressful on the drivetrain than real world scenario's aside for absurd situations such as tornado weather or 50 degree hill climbs, or of course launching a car at 4500RPM on very stick slicks. When you hear of gears being stripped, it's typically on a race track or on a dyno unless the gear itself is faulty/weak or of poor design. *YES gears do get stripped on the street. It does happen. I'm not pretending that it doesn't. It's just not the majority of situations.
Back to point - Because of how a dyno places load on the drivetrain, something that reduces Rotating Assembly (herein: RA) mass/load often is not accurately reflected in the calculated readings, unless the load is reduced significantly from the RA. Notice that you don't find too many dyno claims to support putting a lightened flywheel on a car and not changing anything else. Why? Because a dyno places an abnormal load and condition on the drivetrain. However, we all know that they are good investments and have been used for years in racing successfully. A lightened flywheel operates on the same principle of reducing RA mass, but not load. Removing accessories such as air conditioning reduces RA load, but not mass. An under drive pulley reduces both RA load and mass. Of course, like above, there are some situations in which just a lightened flywheel has been backed up with dyno data, but it's not often. Just as there are times when UD or LW pulleys are backed up by dyno data, but once again, not that often.
A dyno is simply a calculation. It's inherently flawed because there is no specific way to accurately place real load on a drive train. Every dyno manufacturer thinks that they have a better way to do it then the next guy, but in reality - none of them are accurate. They are precise, but not often accurate. Precision is the ability to repeat similar results. That's why you should always use the same dyno when testing new parts. They are good at repeating the same data and changes in it. Accuracy is the degree of closeness to true value. If every dyno was accurate, they would all produce the same results and that rarely happens. Therefore they are all subject to question in the data they produce in terms of being a display of true power.
Dyno's aren't really suitable for placing a drivetrain in a real world atmosphere. They are excellent tools for comparison and analysis, but when it comes being used as a judge for the rate of acceleration of a 2600lb car with a given drivetrain, they are not suitable because they don't place a similar load on that drivetrain that the road or track would. 
The point? Doing a back to back dyno test would likely prove little unfortunately. They produce hard numbers, which black-white thinking people like. 
People that also think in a grey area however will note: 
-A lightened flywheel works because it reduces mass. 
-Removing accessories works because it reduces load.
Underdrive pulleys do both. 
Now, I present to you for your enjoyment, a snowman


----------



## godoveryou (Apr 1, 2007)

*Re: (godoveryou)*

Also, as far as worrying about the electrical system. Unless you are using a lawn mower battery (which I have seen), your battery should be capable of 400-700 amps at 12 volts. That's enough to run most of the accessories in your car for hours and hours. How long have you left the interior light on and were able to start your car? I know I've left my key in the car all night in 30 degree weather and didn't have trouble starting. That's a full 10 hours of radio playing, dash lights, tail lights, marker lights and interior light on with no help from the alt. Maybe my battery is special, but it was $59.00 from walmart so I doubt it.
Yes, if you have something that going to draw an consistant 240 watts or more (that would be 20 amps @ 12 volts, or 17a @ 13.5V), and you plan on idling for more than 30 minutes at a time, then yes, under driving the alt may not be a winning situation. However, I don't know many people that do that. Before the audio guys get angry or up in arms, you have to remember that your 1000watt amp is a peak power rating. You likely never draw anything close to the amperage that would be thought. Most audio amps draw less than 10 amps at any given point in time unless you are a hardcore audiophile. HHO systems use pulse width modulators to reduce the amperage they draw, so they are also not a concern.
For the majority of us, under driving the amp is not a great concern. Specific situations may present specific data to run against that statement, but they are not the average of us.


_Modified by godoveryou at 5:45 PM 12-2-2008_


----------



## dogdog (Jul 26, 2007)

so is the under drive pully actually smaller in diameter or larger, if it is smaller, doesn't the rotation speed actaully increase when the ratio of the pulleys are now different ?


----------



## JBETZ (Feb 17, 2000)

*Re: (dogdog)*


_Quote, originally posted by *dogdog* »_so is the under drive pully actually smaller in diameter or larger, if it is smaller, doesn't the rotation speed actaully increase when the ratio of the pulleys are now different ?

You have it flipped, a smaller diameter pulley means that the accessories will spin slower.


----------



## JBETZ (Feb 17, 2000)

*Re: (dogdog)*

Cool maybe we should make some smaller diameter pulleys for those that want them. http://****************.com/smile/emthup.gif


----------



## godoveryou (Apr 1, 2007)

*Re: (dogdog)*

Smaller. No. It turns the belt at a slower speed. Your engine is going to spin at a given RPM either way. Let say 900 rpm. I'm just going to make up some numbers. Because the UD pulley is smaller, it is spinning less area of the belt per revolution. Let's pretend that the pulley was 9 inches in diameter & the normal pulley was 12 inches. 
900 rpm x 9 inches = 8100 inches of belt travel per minute.
900 rpm x 12 inches = 10800 inches of belt travel per minute.
The less the belt moves, the slower the other pulleys will turn.


----------



## godoveryou (Apr 1, 2007)

*Re: (godoveryou)*

Sorry I didn't know someone else already replied to it. Yes, I think BBM should make them. Beat Eurosport on the weight game as well http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


----------



## tdogg74 (Mar 1, 2002)

*FV-QR*

Whatever.
If I had a choice, I would go with an OEM diameter, light weight pulley over an under drive pulley.


----------



## JBETZ (Feb 17, 2000)

*Re: (godoveryou)*


_Quote, originally posted by *godoveryou* »_Sorry I didn't know someone else already replied to it. Yes, I think BBM should make them. Beat Eurosport on the weight game as well http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif 

I'll leave the under driver for eurosport. no point in all of us making them


----------



## dogdog (Jul 26, 2007)

Thanks godoveryou for the explainations, no I don't think I will go for the underdrive because it's a daily driver, for a few mins there I was confused on the smaller diameter thinggy also. This whole topic was refering to the the crank pully which is the one that drives all other accessories, if the size is smaller, it will drive the accessories at a slower ( assuming that the accessories drive remains at the same size) then again what if the accessories drives are smaller to the same ratio as well.... but then it defeats the purpose of rotational inetria gains ? Dunno but still confused on which is better. but since you mention idle for 30 mins, it can happen in NYC traffics.


----------



## godoveryou (Apr 1, 2007)

*Re: (dogdog)*

Well I'm not trying to sell the units. This is my experience, on many platforms foreign and domestic.


----------



## 2LTurbo (Aug 26, 2008)

honestly one of the best reads ive seen in the 2L forum in a long time, clear information, good poins, civilized dissagreement..... people need to learn from beautiful tech/descussion threads like this


----------



## independent77 (May 23, 2003)

*Re: (2LTurbo)*









excellent read.

http://cgi.ebay.com/ebaymotors...ories
only costs $25. 


_Modified by independent77 at 8:05 AM 12-3-2008_


----------



## WolfGTI (Jun 16, 1999)

*Re: FV-QR (tdogg74)*


_Quote, originally posted by *tdogg74* »_http://gruvenparts.com/website...d=310
Dont go with under drive pulleys...not worth it.

I disagree there Trav, not completely, but partially.


_Modified by WolfGTI at 8:46 AM 12-3-2008_


----------



## tdogg74 (Mar 1, 2002)

*FV-QR*

disagreeing about what...my opinion?


----------



## godoveryou (Apr 1, 2007)

*Re: FV-QR (tdogg74)*


_Quote, originally posted by *2Lturbo* »_honestly one of the best reads ive seen in the 2L forum in a long time, clear information, good poins, civilized dissagreement..... people need to learn from beautiful tech/descussion threads like this


_Quote, originally posted by *independent77* »_excellent read.

Hey guys, just wanted to say thanks. I'm glad that I was able to contribute somewhat to this forum through this discussion in a meaningful manner. I have *A LOT* to learn about VW specific information, so it's nice to know that I can still give a little back from the experience I've gathered through former projects.


_Quote, originally posted by *tdogg74* »_disagreeing about what...my opinion?

Once again, I want to publicly state that I have nothing but respect for Tdog. He has contributed some great information and posted some great dyno's in all the posts I've read of his. I hope to be able to buy one of his old prom's actually, and as a senior member around here I think his opinions should hold some merit. This is just one that him and I don't see eye to eye on, but I am still humbled by his VW experience and knowledge. In the little time that I've been around here actively posting, he has been very kind and helpful and certainly don't want anyone to read my threads thinking that I was somehow slamming his opinion. He certinaly holds many opinions that I value. I also want you to understand that as well Tdog. http://****************.com/smile/emthup.gif


----------



## tdogg74 (Mar 1, 2002)

*FV-QR*

You still want that chip Bri? Its all wrapped up and ready to ship.


----------



## JettaGLBoostd (Oct 14, 2008)

so through all that rambling . . .WHICH IS BETTER


----------



## macanic21 (Feb 20, 2007)

*Re: (JettaGLBoostd)*

light weight + under drive will net you more horsepower.
Here is my thread, someone posted dyno results too!
http://forums.vwvortex.com/zer...44681
So far I have no bad side effects from under drive.


----------



## godoveryou (Apr 1, 2007)

*Re: FV-QR (tdogg74)*

I want it, but cash talks so if you get someone that has it on hand at the momment I completely understand. My head came in, but the wife and I are "Spatting" over Christmas gifts (money). She wants a white one, I want a faster one, lol.


----------



## tdogg74 (Mar 1, 2002)

*FV-QR*

Ill hit you up after the new year then. Currently no bites other than you.


----------



## godoveryou (Apr 1, 2007)

*Re: FV-QR (tdogg74)*

LOL, well from the sounds of it, until I go to FI, our builds will be pretty similar up to that point so it's just about a perfect fit for me. I should have funds avaliable by the middle of the month, but we will see how crazy she goes on shopping before I stick my foot in my mouth.


----------



## tdogg74 (Mar 1, 2002)

*FV-QR*

It doesnt taste bad once you get used to it. Believe me.


----------



## Jay-Bee (Sep 22, 2007)

*Re: (JettaGLBoostd)*


_Quote, originally posted by *JettaGLBoostd* »_so through all that rambling . . .WHICH IS BETTER

Read through the thread yourself and make a decision.
I understand it A LOT more clearly now.


----------



## godoveryou (Apr 1, 2007)

*Re: (Jay-Bee)*

Well guys here's my idea to consolidate a lot of this information:
I bought a eurosport UD pulley from a board member (mk3wagoner89) and I hope it arrives soon. I haven't heard from him for over a week, but I have optimistic faith it will come through. I'm going to order the Ebay Pulley tonight. I'll try to see if Grvuenparts and BBM will either send me samples of theirs that I will send back or if we can work out a purchase and return agreement if it makes them feel better. Then I will do a heads up picture, weight, and dimension comparison of all the units and hopefully get a mod to add it to some kind of general FAQ.
I will compare the following assets:
Weight
Size
Belt offset (from the back of the unit)
Diameter of both the serp and vbelt pulley.
Then take detailed pictures of all 5 of them together, and seperate so that everyone can make informed purchasing decisions on which unit they would like. It would also make for a central source of information on all the units from an independant third party. I think I would have the most difficulty getting gruvenparts to agree to it, only because we minorly bumped heads a bit in one of his threads.
If this sounds like something that you would like to see done, tell me what other facts you would like to see gathered on the pulleys. The only thing I can't provide is Dyno information for 2 reasons. 1st, time is money there and unless someone can get me free dyno time I can't do much to help. The second reason is that I wouldn't want to install the BBM or GP pulleys since I would want to return them in the same condition I received them in. I could possibly use a little assistance greasing the wheels if you will with both BBM and GP so that would help.
If you think it would be a waste of time or lack interest in seeing that information also please let me know. I don't want to spend a whole afternoon taking pictures and measurements if nobody has interest in it.
Thanks,
GOY


_Modified by godoveryou at 12:54 PM 12-3-2008_


----------



## JBETZ (Feb 17, 2000)

*Re: (godoveryou)*

That seems like allot of wheels spinning for some basic information. 
Our offset, diameter and tolerances are balls on the nut.
I would also guess that the GP unit is also correct in this regard.
I'd question the ebay units bore tolerances and concentricity.
The rib geometry is also important, ours is to the SAE standard.
Unless you plan on using bore gage's and micrometers and have the knowledge to measure in the tenths this is really pointless.
The only thing you need from us is the exact weight and I can just post you this information. 
Just some friendly feed back.











_Modified by JBETZ at 1:29 PM 12-3-2008_


----------



## godoveryou (Apr 1, 2007)

*Re: (JBETZ)*

That's welcome feedback, and yes I have a complete master machinists precision measurement set that is worth more than the Jetta itself, so I could take just about any measurement needed. I understand how you feel about the ebay unit. *That's exactly why I thought it important to make a complete pulley related faq sheet from a third party. That way end users would know exactly what was a well machined item and what wasn't - including the OEM factory pulley. They would also have all the information about various differences between the units. I don't see this hurting sales for any company out there. In fact, making this information more widely avaliable would likely promote sales. But if you feel that it would be a worthless project, that is also equally important feedback for me personally.



_Modified by godoveryou at 1:48 PM 12-3-2008_


----------



## JBETZ (Feb 17, 2000)

*Re: (godoveryou)*

It is up to you if you think this is worth your time. I'll get my ass out in the shop and a pulley on the scale and give you guys a weight number here. I just have to dig out from under this pile on my desk right now... not going to happen today.










_Modified by JBETZ at 9:56 AM 12-4-2008_


----------



## ghoastoflyle (Jan 21, 2003)

*Re: (2LTurbo)*


_Quote, originally posted by *2LTurbo* »_honestly one of the best reads ive seen in the 2L forum in a long time
 http://****************.com/smile/emthup.gif Seriously, I couldn't agree w/ you more, excellent discussion here. Hope to hear more info on the light weight side of the argument, but I admit I don't know enough to weigh in on any side. 
Gonna have to reread the dyno part, as it was over my head. But I've had a ruff week and had a few. So I'll save my questions 'till I got a focused mind lol. Thanks


----------



## pilonius (Feb 6, 2008)

Looking forward to seeing a FAQ pulley thread. http://****************.com/smile/emthup.gif


----------



## godoveryou (Apr 1, 2007)

*Re: (JBETZ)*

Ordered Ebay pulley, heard back from the supposed seller of the eurosport pulley. Things on track to make that FAQ happen.


----------



## Jay-Bee (Sep 22, 2007)

*FV-QR*

I like where this thread went.
http://****************.com/smile/emthup.gif


----------



## JBETZ (Feb 17, 2000)

Ok, so our 8V pulley is exactly 2.2lbs
When we first started making these billet pulleys they were mainly done up for ABA 16V head conversion guys. We also sell that same version for 1.8T swaps. It was easy for us to tweak the design for this 8V application. Our pulley also provides an extra two ribs so that you can convert to an 8 rib serpentine belt system. This was done for the use of a wider serp belt for driving higher boost superchargers. The wider belt provides better belt traction for higher hp. So ours might not be the lightest one out there, at the time this was not really what we were trying to achieve.


----------



## Salsa GTI (Aug 29, 2000)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_That seems like allot of wheels spinning for some basic information. 
Our offset, diameter and tolerances are balls on the nut.
I would also guess that the GP unit is also correct in this regard.
I'd question the ebay units bore tolerances and concentricity.
The rib geometry is also important, ours is to the SAE standard.
Unless you plan on using bore gage's and micrometers and have the knowledge to measure in the *tenths* this is really pointless.
The only thing you need from us is the exact weight and I can just post you this information. 
Just some friendly feed back.









_Modified by JBETZ at 1:29 PM 12-3-2008_

Tenths..seriously John..you can measure that on a 6 inch scale that's hardly precision








I can see why you would not use one as you are a supercharger guy...so for you it would be counter productive.


----------



## Salsa GTI (Aug 29, 2000)

*Re: (Salsa GTI)*

and "godoveryou"

excellent points and explanations....
I usually do not get that far into explaining things......
I have little patients for people...........
SO typical i start with hate....and progress to severe hate very quickly 
Well done sir









I would have just hated them all to death...


----------



## godoveryou (Apr 1, 2007)

*Re: (Salsa GTI)*


_Quote, originally posted by *Salsa GTI* »_and "godoveryou"
i start with hate....and progress to severe hate very quickly 

You've directed some of that hate this direction in the past, so I'm very aware of that







Thank you very much though. I do appreciate it... not the hate, the other stuff, lol.


----------



## JBETZ (Feb 17, 2000)

*Re: (Salsa GTI)*


_Quote, originally posted by *Salsa GTI* »_
Tenths..seriously John..you can measure that on a 6 inch scale that's hardly precision








I can see why you would not use one as you are a supercharger guy...so for you it would be counter productive.

yes seriously , the bore tolerance is in tenths and we measure it with a bore gage. not good to have your crank pulley spinning off center. our supercharger pulley bores are also in the tenths.


----------



## Salsa GTI (Aug 29, 2000)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_
yes seriously , the bore tolerance is in tenths and we measure it with a bore gage. not good to have your crank pulley spinning off center. our supercharger pulley bores are also in the tenths.


Yes tenths of a thousandth of an inch ..the 5th place after the decimal point.
not tenths of an inch AKA type setting and printing








I'm well aware of the term.....Machinist also....amoung other things.


----------



## Salsa GTI (Aug 29, 2000)

*Re: (godoveryou)*


_Quote, originally posted by *godoveryou* »_
You've directed some of that hate this direction in the past, so I'm very aware of that







Thank you very much though. I do appreciate it... not the hate, the other stuff, lol.

Thats because your the new guy








and this subject has been beaten to death......
But now is having a proper discussion....


----------



## tdogg74 (Mar 1, 2002)

*Re: (Salsa GTI)*

Quit being such a ***** Dave.


----------



## relmonte (Dec 7, 2005)

I've wonder what the difference was between lightweight and underdrive pulleys AFTER I bought an underdrive pulley.
I've never had a problem with my pulley (Ebay).


----------



## Salsa GTI (Aug 29, 2000)

*Re: (tdogg74)*


_Quote, originally posted by *tdogg74* »_Quit being such a ***** Dave.









you don't like underdrive pullys so you know what i think


----------



## JBETZ (Feb 17, 2000)

*Re: (Salsa GTI)*

This has been a good thread, what is the matter with you people... Stop being so nice in here


----------



## godoveryou (Apr 1, 2007)

*Re: (JBETZ)*

JBETZ, do you answer the company emails? I have a couple questions, don't want to have to go through a bunch of channels and the PM's are disabled. If you have someone else handle emails, shoot me a line at godoveryou at aol dot com. They are just quicky's.... I hear you like it that way.


----------



## JBETZ (Feb 17, 2000)

*Re: (godoveryou)*


_Quote, originally posted by *godoveryou* »_JBETZ, do you answer the company emails? I have a couple questions, don't want to have to go through a bunch of channels and the PM's are disabled. If you have someone else handle emails, shoot me a line at godoveryou at aol dot com. They are just quicky's.... I hear you like it that way.
















everyone likes a quickie, lol








you can email direct at [email protected]


----------



## cstocks (Aug 2, 2007)

*Re: (JBETZ)*

I've read through the entirety of this thread and being a newer memeber feel that this is a must read to any n00b to be less ignorant. I'm not hear trying to be a brown noser, just shedding some light on the senior members that not all n00bs are allergic to the search button. Great write-up and I love the relations with bahnbrenner in the thread. I havn't even thought of doing pulleys, but after this post its my next buy. Great write-up! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


----------



## JBETZ (Feb 17, 2000)

*Re: (Salsa GTI)*


_Quote, originally posted by *Salsa GTI* »_

Yes tenths of a thousandth of an inch ..the 5th place after the decimal point.
not tenths of an inch AKA type setting and printing








I'm well aware of the term.....Machinist also....amoung other things.









4th place after the decimal .0001"


----------



## TMTuned99.5Golf (Jan 27, 2004)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_
4th place after the decimal .0001"










But it's more fun to measure in the millionths!!


----------



## JBETZ (Feb 17, 2000)

*bump it*

bump'in it http://****************.com/smile/emthup.gif


----------



## LangsamKafer (Jul 17, 2001)

Added to 2.0L FAQ - Tech section.


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (LangsamKafer)*

Did godoveryou ever get back to anyone with specs???


----------



## ghoastoflyle (Jan 21, 2003)

*Re: (NeonGreenbangbang)*

I think he's been black holed.


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (ghoastoflyle)*

Black holed? Banned? That sucks. Wonder what he did.


----------



## Jay-Bee (Sep 22, 2007)

Oh, I see what you did there.










_Modified by Jay-Bee at 4:40 PM 12-20-2008_


----------



## Salsa GTI (Aug 29, 2000)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_
4th place after the decimal .0001"










And I should not drink and vortex


----------



## JBETZ (Feb 17, 2000)

*Re: (Salsa GTI)*


_Quote, originally posted by *Salsa GTI* »_
And I should not drink and vortex


----------



## MkIII_Paul (Sep 7, 2008)

*Re: (JBETZ)*

Not to beat a dead horse, but I do have some misgivings involving under drive pulleys and alternators. I think the pumps can run at lower rpm's without any problems in reasonable environmental conditions, but having the alternator generate the proper voltage would be very important _to me_.
_I believe_, that a quality under drive pulley paired with an alternator pulley reduced proportionally in order to keep the original ratio would be ideal. Obviously, one would only be under driving the remaining components in this case.
Just my two cents.


----------



## kungfoojesus (Jan 10, 2005)

In a closed loop cooling system, the rate of flow matters very little for all practical situations within the realm of this under drive discussion.
As far as these measurements go, has anyone measured OEM pulleys? I want to know what their tolerances are as far as roundness, balance, concentricity etc. Are manufacturers building expensive replacement parts to excessively tight tolerances that are entirely beyond anything VW ever intended for this application?
Perhaps in this sense the ebay pulley, measured with a ruler and machined by a dremel, is the best deal after all?
I'm not saying expensive parts aren't worth it. It is just some of us are more price sensitive than others, as any good businessman knows.


_Modified by kungfoojesus at 2:17 AM 12-25-2008_


----------



## vwantihero (Dec 18, 2006)

*Re: (kungfoojesus)*

soooo, with all arguments said and done is the verdict that an underdrive pulley set is good, worth it? cause i am completely lost with all the mechanical jargon. i would like laymens terms please. please excuse my noobness on mechanical things


----------



## kungfoojesus (Jan 10, 2005)

They are worth it to some people and not worth it to others. Your question is highly subjective.
In theory they work, but how effectively is another question! This can only be answered through a lot of expensive equipment, software, and time. None of which anyone is volunteering.


----------



## justn868 (Jan 20, 2008)

*Re: (kungfoojesus)*

alot of good information in this thread http://****************.com/smile/emthup.gif


----------



## Salsa GTI (Aug 29, 2000)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_This has been a good thread, what is the matter with you people... Stop being so nice in here









How about this........
You have stock pulley's
OR lightened stock diameter pulley's
I have E-Gay under-drive pulley's..........
We race........
You shut up..........
End of story..................
How's that John......
Is that Un- Nice Enough


----------



## independent77 (May 23, 2003)

*Re: (Salsa GTI)*

yea, **** off.
~mike.


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (independent77)*

I'm doing all the measurements on the ebay unit today. I'll post when I have the solid data, but the ebay unit is actually a pretty good unit from my first impression. It only has one flew in it's machining.


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (NeonGreenbangbang)*

The Ebay Pulley:
Inital opinion - well machined overall. The rear of the serp pulley has lightening holes drilled into it and that were likely the last stage of machining as the holes have material "Lips" on the openings. They were never planed or filed off. Visually, the lightening holes appear to be off center from each other very slightly but it's hard to see clearly with the extra material there. Therefore I did 2 series of measurements for the aspects that would be affected before and after I planed the material off. The static weight distribution or balance of the pulley will be "Off" based on how Volkswagen designed the system. There is a centering peg on the crankshaft that fits into the pulley. There is an access hole that allows for room of the peg, and it's only on one side of the pulley so unless it was counterweighted, there's no way to make the pulley perfectly balanced. That having been said, not even the factory pulley has a counter weight on it that I see, nor does any aftermarket unit. Balancing was measured on a 1200 point static weight distribution scale. Measurements were taken with a depth gauge, mechanical calipers, mechanical space gauge, and mechanical slide rule.
Pre-finishing.
Weight: 681.336 grams
Static weight distribution: 98.601% of perfect
Hub center bore to bolt distribution: Within .001mm of each other
Hub depth to serp pulley rear face: Within .001mm for 360 degrees
3rd Rib of serp pulley to rear of hub: Within .001mm for 360 degrees
Serp Pulley width: Within .001mm for 360 degrees
Lightening holes:
-Within .3mm of each other - heavy material interference observed.
-Within .1mm of hub - material interference observed.
-Within .1mm of outer face - material interference observed.
Post-finishing
(I planed mine, but a file from Home Depot would work nearly as well.)
Weight: 679.101 grams
Static weight distribution: 99.119% of perfect 
-This is about 99.999% given the fore mentioned peg hole by my estimation
Lightening holes
-Within .001mm of each other
-Within .001mm of hub
-Within .001mm of outer face
I was ***SHOCKED*** as I tend to equate cheap machining with poor machining. While I didn't use the laser equipment to make absolute measurements, I trust the mechanical instruments for the numbers. They were around long before optic measuring and have served me very well in my projects. I'd still like to compare for myself to other pulleys on the market. I never received the Eurosport unit, mk3wagooner89 scammed me.
Bottom line - if you don't mind spending 5-10 minutes with a file this is an excellent buy, and a good item. If you don't want to file it, it will likely perform just fine given the inherent design flaw in balance right from VW's design desk.
GO..... errrrr...... NeonGreenBangBang











_Modified by NeonGreenbangbang at 1:07 PM 12-28-2008_


----------



## independent77 (May 23, 2003)

*Re: (NeonGreenbangbang)*


----------



## pilonius (Feb 6, 2008)

More numbers!!
j/k 
Thanks for the useful info!


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (pilonius)*


_Quote, originally posted by *pilonius* »_More numbers!!

I'm big on numbers to an extent.....


----------



## vwantihero (Dec 18, 2006)

*Re: (NeonGreenbangbang)*

so are underdrive pulleys worth it or what


----------



## independent77 (May 23, 2003)

*Re: (vwantihero)*


_Quote, originally posted by *vwantihero* »_so are underdrive pulleys worth it or what

reread the last 3 pages and ask yourself that.


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (vwantihero)*


_Quote, originally posted by *vwantihero* »_so are underdrive pulleys worth it or what

For me personally, they suck and aren't worth the time. That's why there's one on my crankshaft as we speak


----------



## Borg-Omen (Jun 15, 2007)

*FV-QR*

just my 2cents.
i have the eurosport underdrive crank pulley , and my headlights dim and my ac/heat blows softer (the volume of air being pushed through the vents) at idle . when i bring up the rpm's they go back to normal.
im actually looking into non underdrive (just lightweight) pulley's ( i would end up doing the PS and Alt. pulleys) to see if it will stop this.

could this have actually caused damage to the alternator? 
(i know, my post was kind of a 2cents + question kind of thing)


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: FV-QR (Borg-Omen)*

Highly unlikely. Your car was running on the 12v battery rather than the 13.8-14.3v alternator during those periods. That's why you noticed those effects. If you want to donate your pulley to science for a small price, let me know. LOL.


----------



## Borg-Omen (Jun 15, 2007)

*FV-QR*

how small of a price








i was thinking about picking up a new battery anyhow. cuz cold starts are getting painfull


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: FV-QR (Borg-Omen)*

You tell me. Take it to PM's though, this isn't the classifieds section... http://****************.com/smile/emthup.gif Gotta keep it moderator friendly and all.


----------



## B5Buddy (Jun 17, 2004)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_
I'll leave the under driver for eurosport. no point in all of us making them









i got my eurosport udp as one of my first mods it was easy to do, good quality, and i think it was actually the best mod besides my cam. the pulley didnt cost much and the butt dyno showed significant results where as the cam was a bit of a pain in the arse it didnt cost much either and DEFINATLEY had a great noticable gain. not to side track here but id say for the bang for buck mod the pulley and cam had best results i gained low, and midrange tourque!!! perfect for average driving with something there to have fun with goodluck with your decision btw the Eurosprt is under dirven AND light weight significantly too







http://****************.com/smile/emthup.gif


----------



## vwantihero (Dec 18, 2006)

*Re: (independent77)*


_Quote, originally posted by *independent77* »_
reread the last 3 pages and ask yourself that.

i read the last 3 pages and i just didn't understand all the mumbo jumbo so i just wanted a straight up answer..thanks for being a jerk http://****************.com/smile/emthup.gif


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (vwantihero)*


_Quote, originally posted by *vwantihero* »_
i read the last 3 pages and i just didn't understand all the mumbo jumbo so i just wanted a straight up answer..thanks for being a jerk http://****************.com/smile/emthup.gif 

He's not being a jerk, you are being lazy. It's not a simple answer. All that "mumbo jumbo" is the information required to make an informed decision. That's like you asking someone whether to go NA or FI. It's up to what YOU want, not us.....


----------



## vwantihero (Dec 18, 2006)

*Re: (NeonGreenbangbang)*


_Quote, originally posted by *NeonGreenbangbang* »_
He's not being a jerk, you are being lazy. It's not a simple answer. All that "mumbo jumbo" is the information required to make an informed decision. That's like you asking someone whether to go NA or FI. It's up to what YOU want, not us.....

one more jerk http://****************.com/smile/emthup.gif


----------



## Pitsy (Oct 27, 2007)

*Re: (vwantihero)*


_Quote, originally posted by *vwantihero* »_
one more jerk http://****************.com/smile/emthup.gif 

Hey, he may be a jerk, but what that jerk said was true. The entire thread was all about your question. Don't get mad when someone tells you to read a few pages. This is a discussion forum, not a list of answers.


----------



## 2LTurbo (Aug 26, 2008)

neongreenbangbang a jerk?! WTF ARE YOU SMOKING!!!? he did all that work with the ebay pully for all of us on here so we would know about it , even did a well written write up on the topic and you hae the never to call him a jerk!?


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (2LTurbo)*

I can't please everyone....


----------



## independent77 (May 23, 2003)

*Re: (NeonGreenbangbang)*


_Quote, originally posted by *NeonGreenbangbang* »_I can't please everyone....

Don't worry, He is from Florida.


----------



## vwantihero (Dec 18, 2006)

*Re: (independent77)*


_Quote, originally posted by *independent77* »_
Don't worry, He is from Florida.
whats wrong with florida, i understand that he did all the work and ran the numbers..but me being not understanding what it all means doesn't mean you guys have to start flaming...It was a simple question, maybe too simple. so ill ask a different one of the same nature..
In laymen's terms, What are the benefits, and what are the bad points of having this mod? 
excuse me for calling neon a jerk i apologize.


_Modified by vwantihero at 7:20 PM 1-20-2009_


----------



## vwantihero (Dec 18, 2006)

*Re: (2LTurbo)*


_Quote, originally posted by *2LTurbo* »_neongreenbangbang a jerk?! WTF ARE YOU SMOKING!!!? he did all that work with the ebay pully for all of us on here so we would know about it , even did a well written write up on the topic and you hae the never to call him a jerk!?

Northern Lights Cannabis indica


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (vwantihero)*

They started flaming you because you called me a jerk for trying to point out that the thread is this long because all that space was used explaining all the answers to the questions you are now asking.
There is no simple answer sir. It's not my fault, nor am I a jerk because it's not simple. I'm a jerk because of how I word things and my opinions on certain issues. Completely different reason










_Modified by NeonGreenbangbang at 4:52 PM 1-20-2009_


----------



## 2LTurbo (Aug 26, 2008)

seriously this isnt the spoon feed me **** because im an effin ar-tard forums.. do you want me to teach you some differential equations too? how about the intricacies of a 24 channel data mux.... sheesh some peeps


----------



## MkIII_Paul (Sep 7, 2008)

*Re: (vwantihero)*


_Quote, originally posted by *vwantihero* »_
In laymen's terms, What are the benefits, and what are the bad points of having this mod? 

sigh....
the good: you will get slightly more power to the wheels (lower single digits). 
you may also experience a slight increase in gas mileage (an additional fraction of a mile per gallon), but since you are probably looking for more hp, you wont get it due to your driving style.
the bad(?): your accessories will spin slower.
this is a point of contention, so it is up to you to decide if slower spinning accessories are actually bad for your car and its intended purpose.
there are other finer points to this mod, which have been discussed in this thread... but you asked for the "laymen's" version.


----------



## NoStoDubbin (Dec 2, 2008)

*Re: (vwantihero)*


_Quote, originally posted by *vwantihero* »_
Northern Lights Cannabis indica

florida boy smoked something right http://****************.com/smile/emthup.gif


----------



## Fast VW (Sep 24, 2002)

*Re: (NoStoDubbin)*

I did a lot of searching on these as well a couple of years ago. The only thing I remember reading that made me stay clear was a comment from Dick Shine. He said that in many of the VW 4 cylinder motors he had rebuilt that had been running LW or UDP, he found excessive bearing wear. He said that it had been enough to convince him to not recommend these.
Anyone have any thoughts?


----------



## MkIII_Paul (Sep 7, 2008)

*Re: (Fast VW)*

In my opinion, UDP's should extend the life of accessory bearings, since the accessories will be spinning slower than stock. There should be absolutely no change in bearing wear with a LW pulley, since everything spins at stock rates. 
Excessive belt tension could wear out bearings pretty quickly.


----------



## Fast VW (Sep 24, 2002)

*Re: (MkIII_Paul)*

Sorry that was not very clear. Dick Shine was referring to the crank bearings, not accessory bearings, wearing excessively/abnormally because of the reduction in weight of the crank pulley.


----------



## NeonGreenbangbang (Dec 20, 2008)

*Re: (Fast VW)*

Both the accessory and crank bearing lives should be extended but for different reasons. Of course, since people that typically modify their engines rev them a bit higher than the normal driver - it might as well be a wash on the crank bearing.


----------



## Fast VW (Sep 24, 2002)

*Re: (NeonGreenbangbang)*

If I can find that thread I will quote it or post a link. If I remember correctly he was referencing vibrations caused by harmonics. The best example I can remember is relating it to building a subwoofer box. 
The enclosure is going to vibrate at a certain frequency regardless of what you do but the goal is to get the vibration at a frequency outside of the operating range of the sub. If you use MDF to build it you are making the enclosures mass greater and therefore lowering the resonate frequency below the operating range of the sub. Not a great example, but I think you will get the point. The heavy crank pulley moves the vibration outside the operating range of the engine.
I could never find anything to prove or disprove the idea, so errored on the side of caution and never purchased one.
If anyone can provide some info to actually prove or disprove the long term negative affects on the crank bearings that would be great.


----------



## bobsled (Aug 25, 2006)

*Re: (Fast VW)*


_Quote, originally posted by *Fast VW* »_If I can find that thread I will quote it or post a link. If I remember correctly he was referencing vibrations caused by harmonics. The best example I can remember is relating it to building a subwoofer box. 
The enclosure is going to vibrate at a certain frequency regardless of what you do but the goal is to get the vibration at a frequency outside of the operating range of the sub. If you use MDF to build it you are making the enclosures mass greater and therefore lowering the resonate frequency below the operating range of the sub. Not a great example, but I think you will get the point. The heavy crank pulley moves the vibration outside the operating range of the engine.
I could never find anything to prove or disprove the idea, so errored on the side of caution and never purchased one.
If anyone can provide some info to actually prove or disprove the long term negative affects on the crank bearings that would be great.

Hate to butt my head in here, but this makes sense to me. http://****************.com/smile/emthup.gif 
Much like how lightened flywheels have been proven to cause crank bearing failure due to being able to rev much more quickly. Although the flywheel is almost always going to be heavier than a crank pulley.


----------



## JBETZ (Feb 17, 2000)

been waiting forever for someone to mention this... haha that's why they call it a harmonic balancer







there are some really good old school technical / engineering articles out there on this topic http://****************.com/smile/emthup.gif 
peace


----------



## Cgarcia (Apr 4, 2004)

*Re: (JBETZ)*

That is true, but I've also heard that the pulley on our engines is not a harmonic balancer, just a pulley. Of course, I have no way to verify that.


----------



## JBETZ (Feb 17, 2000)

*Re: (Cgarcia)*


_Quote, originally posted by *Cgarcia* »_That is true, but I've also heard that the pulley on our engines is not a harmonic balancer, just a pulley. Of course, I have no way to verify that.

it has a harmonic dampener built into it. you should put your hands on a G60 PG harmonic dampener, my word talk about sherman tank like parts


----------



## Fast VW (Sep 24, 2002)

*Re: (Peter Tong)*

Over the years I have watch all of these threads end the same way:
1. Yes they free up power
2. Maybe the OEM part is a Harmonic or Torsional Dampener and maybe it isn't.
3. Maybe a LW or UDP will harm the bearings and maybe it won't.
4. Maybe you will get more knock sensor activity and maybe you won't.
I was hoping for a different ending this time. Oh well, I spend money on something else.


----------



## JBETZ (Feb 17, 2000)

*Re: (Fast VW)*


_Quote, originally posted by *Fast VW* »_Over the years I have watch all of these threads end the same way:
1. Yes they free up power
2. Maybe the OEM part is a Harmonic or Torsional Dampener and maybe it isn't.
3. Maybe a LW or UDP will harm the bearings and maybe it won't.
4. Maybe you will get more knock sensor activity and maybe you won't.
I was hoping for a different ending this time. Oh well, I spend money on something else.









1. yes they free up a *little *power
2. yes the OEM part is a harmonic dampener, this is fact.
3. yes there are adverse affects to the bearings and possibly other engine parts... how much on a VW engine and if it even matters... unknown.
4. never thought of this one... i wouldn't think this would come into play at all. the knock sensor is tuned for a specific knocking frequency








I see PT has been lurking on this one and now has posted http://****************.com/smile/emthup.gif 
What do you think Pete?


----------



## Fast VW (Sep 24, 2002)

*Re: (JBETZ)*


_Quote, originally posted by *JBETZ* »_
1. yes they free up a *little *power
2. yes the OEM part is a harmonic dampener, this is fact.
3. yes there are adverse affects to the bearings and possibly other engine parts... how much on a VW engine and if it even matters... unknown.
4. never thought of this one... i wouldn't think this would come into play at all. the knock sensor is tuned for a specific knocking frequency








I see PT has been lurking on this one and now has posted http://****************.com/smile/emthup.gif 
What do you think Pete?

Well that takes care of that. I will now watch all of the UDP and LWP threads and chuckle. http://****************.com/smile/emthup.gif 
I read in a post a couple of years ago about someone who put a set of "Power Pullies" on a 1.8T and actually lost power and they determined that it due to increased knock sensor activity. But then again maybe my memory has failed.







Regardless the other items are enough for me to stay clear. I think there might be other ways to increase power. LOL


----------



## Cgarcia (Apr 4, 2004)

*Re: (JBETZ)*

I was just wondering, if it is a harmonic dampener, is it there for comfort or to keep the engine from shaking itself to pieces?


----------



## JBETZ (Feb 17, 2000)

*Re: (Cgarcia)*


_Quote, originally posted by *Cgarcia* »_I was just wondering, if it is a harmonic dampener, is it there for comfort or to keep the engine from shaking itself to pieces?

To keep the engine from shaking itself to pieces







I guess the extra vibration on some engines can cause increased bearing wear and even possible cracking of the crank shaft. I've been running these billet pulleys on my cars for many years now with no ill affects.
I've not seen any detrimental affects to support this on the VW engines. I did read a very long tech article on this topic, it was in reference to a Chevy V8 small block engine. 




_Modified by JBETZ at 1:04 PM 1-22-2009_


----------



## Fast VW (Sep 24, 2002)

*Re: (Cgarcia)*

This is what I do best, read posts for years and years and then only post when it's time to put fear and doubt into everyone's minds.








I now fade back into the shadows.....


_Modified by Fast VW at 4:05 PM 1-22-2009_


----------



## JBETZ (Feb 17, 2000)

*Re: (Fast VW)*


_Quote, originally posted by *Fast VW* »_This is what I do best, read posts for years and years and then only post when it's time to put fear and doubt into everyone's minds.








I now fade back into the shadows.....
_Modified by Fast VW at 4:05 PM 1-22-2009_

glad you came out shadow master. i usually try to avoid these controversial tech topics as they usually draw out the a'holes and turn into flame fests.
peace


----------



## Borg-Omen (Jun 15, 2007)

*FV-QR*

i have the Eurosport UDP . hope my ish doesnt break








the slower spinning accessories kind of urks me though.


----------



## MkIII_Paul (Sep 7, 2008)

*Re: FV-QR (Borg-Omen)*

reving too fast is one thing. shaking itself apart is entirely different.
the accessories act much more like torsional harmonic dampers than the pulley itself does. and since the pulley only makes a marginal change to the powerplant system overall, i would highly doubt it would cause such a great change in the natural frequency of the system. 
harmonic frequencies would only come into play at specific frequencies (rpms), not at rates of change of those frequencies.
i would also highly doubt that the factors of safety (on production engines such as ours) are so slim that a slight change in pulley diameter could cause a great shift in the wear of components. 
once again, it all comes down to treating a pig like a racehorse.


----------



## npung09 (Dec 4, 2008)

What i have always thought about underdrive pulleys was...
run in normal shoes on grass.
then run in cleetes.
feel the difference?


----------



## 2LTurbo (Aug 26, 2008)

very generalized statement


----------



## vwantihero (Dec 18, 2006)

*Re: FV-QR (Borg-Omen)*


_Quote, originally posted by *Borg-Omen* »_i have the Eurosport UDP . hope my ish doesnt break








the slower spinning accessories kind of urks me though.

irks







...
btw thanks for the non-engineer answers im sure you guys helped more than just me on this topic cheers!


----------



## liquid96gold (Jan 18, 2011)

i plan to eventually do underdrive pulley to my car. i think an upgraded battery like a yellow top and hids would solve all the issues with acc power loss and a/c kills my gas milage anyway. so to me it seems like a good investment


----------



## mizzuh (Oct 13, 2010)

I have an optima yellow top. I've had it for 7 years now, killed it DEAD probably 5 or 6 times, and I picked it up USED.


BEST. INVESTMENT. EVER

ps, great thread, the big issue surrounding aftermarket pullies in general is their "make quality" and "purpose" in conjunction with the original OEM parts.

it seems to me (just my opionion) that it all pretty much goes back to "you get what you pay for".

you buy a good quality, balanced, cnc machined part from a reputable vendor, then you are probably going to have no issues, underdrive or not. mathmatically, underdrive is better (rotational mass, reduced force exerted, etc etc). in the real world? jury is still out. you have a LOT of things to factor in. remember, that ONE PULLY is attached to the driving force of your motor.


----------



## Salsa GTI (Aug 29, 2000)

OMFG ........
Back from the mother f***ing dead.........
THe cheep ass ebay pulley never failed me....320whp 329wtq
ran the pulley for 3 years no charging or cooling issues PEople play with themselves...i ran a wall mart lawn tractor in my car.....with 2 amps for the stereo and working ac power windowes and mirrors..MK2 ABA in case noobs dont know this....no issues ever
car still running great with new owner taking over adding improvements and scaring old D bags in Vetts for life....Oh the fun.....I need a new toy


----------



## mrbatavus (Nov 29, 2008)

if in fact the stock pulley is a harmonic balancer, then removing this item and replacing it with a non harmonic dampening pulley is allowing harmonics to wreak havoc upon the engine

i may have slightly over dramatized that but the job of a harmonic dampener is to dampen the torsional vibrations of the crankshaft

whether you want to believe it or not the cylinder pressures are not the same in each cylinder no matter how much work and money you put into it, this in turn changes the torque put on the ever flexing and twisting crankshaft the harmonic balancer helps dampen these vibrations and to smooth out the power

on sbc's its been known to crack crankshafts with a bad harmonic balancer and I've yet to meet someone who dared run one without one.

if you do some research the people that spend 400 dollars on a professional harmonic balancer much better then what the factory produced they noticed increases in power and a smoother application of it as well

anyone who works on boats as a living knows that harmonics of an engine can crack a hull 

will you still buy this item? yes
will it work for what its advertized for? yes
will it cause catastrophic engine damage? in theory it could but apparently has not
will i buy one? if i can get a used one cheap enough 

if your going to nitpick my grammar go :banghead: cause i don't care

my 2 cents


----------



## VeeDoubleYouGuy (Nov 4, 2003)

i know guys who race dodge neons circle track and run belt-less: just a good battery and the water pump is run off the timing belt and no power steering. why? more power. ya when you're out there for just 30-60 minutes, it's do able. (mind you aba's cant do this because the water pump is run off another belt). so basically for racing where there are specific rules, every bit counts. thats why lots of these parts exist from a need for racing. but if you're actually driving this car thats another story. 
i guess a lightweight pulley reduces moment of inertia so it makes it easier for the engine to turn it== performance gain
underdrive pulley can net some good gains because the accessories are a load on the system, so its like a 10 speed bike, change the gear and its easier to turn the belts and therefore there is more power available to the wheels.
i like what was said about sbc's and proper harmonic balancers. it all depends on the RPMs and what you are going to use it for. its a cheap mod and it makes power. how fast do you wanna go and how much do you wanna spend? i think that turbo's are the best bang for the buck personally.


----------



## gamefoo21 (Jul 4, 2009)

It depends on the engines, if they are internally balanced, each item to itself, then you can usually get away with it. On SBC's for example Cranks are balanced with the flywheels and the balancers.

Inline 4's are horrible for vibration along with V8's, Inline 3's and V6's tend to be the most balanced.

For the small gains, you get from a lightened pulley, these aren't exactly the greatest inline 4's ever designed/built, and they tend to shake quite a bit, I wouldn't exactly risk it. Faster you rev em, the harder it gets on bearings/rods/block/etc.


----------



## Fast VW (Sep 24, 2002)

gamefoo21 said:


> It depends on the engines, if they are internally balanced, each item to itself, then you can usually get away with it. On SBC's for example Cranks are balanced with the flywheels and the balancers.


Just to clarify:

Whether and engine is internally or externally balanced, does not indicate whether or not it needs a HARMONIC damper. The VW crankshaft pulley is a harmonic damper not a balancer.

Carry on. opcorn:


----------



## Jon_2.0slow (Oct 4, 2011)

*Eurosprt UD*

Hey just ordered my eurosport udp the other day just waiting for it to come in and was wondering if anyone knew the right belt size for my set up before i try and figure it out or mock it up and realize no shop has the size. I have a 2.0 94 aba with P/S and A/C deleted running the water pump with a vr6 version pulley off the alternators belt and was curious if anyone else had done this? 
Gonna have my buddy weigh it at his work and possibly do some 0-60 times with his vag-com link and computer not sure how technical the info is from a 94 ecm but maybe it'll show a slight hp bump.


----------

