DIscussion about UR lightweight pulleys MOVED from GB thread)

[eminence]

Personally, I don't recommend using a non-dampened pulley for the 2jz crank as it will produce some vibration that will cause problems for the motor. The pulley might be balanced and all but it's not a dampened pulley like OE, ATI, OR BOOSTLOGICS unit which are two piece, liquid filled to absorb all the vibration. I would trust Toyota's engineer over any aftermarket company anyday. It's might be lightweight but so will be your wallet once the motor shits the brick.

Just my 2 cents

[stjarvis]

Is the alternator pulley underdriven, or just the crank pulley? I wish they had a stock sized set for us.

[IS300NA-T]

Is the alternator pulley underdriven, or just the crank pulley? I wish they had a stock sized set for us.

Im pretty sure its the crank pulley.

there real shiny but i might powder coat them to match my intake

http://i70.photobucket.com/albums/i84/vtechkiller/intake/DSCN0501.jpg


But i am going to need to powder coat this piece too

http://i70.photobucket.com/albums/i84/vtechkiller/uninstalled%20parts/DSCN0499.jpg


going buck wild with the parts this month lol these will be my last mods to the car since i wont be going boost :)


You shouldve bought the titan motorsports one since those are already red. :D

[boosted_drew]

Personally, I don't recommend using a non-dampened pulley for the 2jz crank as it will produce some vibration that will cause problems for the motor. The pulley might be balanced and all but it's not a dampened pulley like OE, ATI, OR BOOSTLOGICS unit which are two piece, liquid filled to absorb all the vibration. I would trust Toyota's engineer over any aftermarket company anyday. It's might be lightweight but so will be your wallet once the motor shits the brick.

Just my 2 cents

i have heard many different views on this. i have seen somepeople with this on for 3 years and still no damage. i also asked UR about this and the guy on the phone said he had these on his supra for a few years already and said that the claim that they will cause damage to the engine was BS and his arguement was that they had been in business for 11 years and if it caused damage they would have already closed down. but i dont want this to get into another debate so if someone wants to start a new thread to debate thats fine this is just for people who want to purchase this. I personally only got the accessorys but am now thinking about doing the crank as well.

I can also probably get cam gears from UR if anyone is interested. ill call tomorrow for price

[eminence]

i have heard many different views on this. i have seen somepeople with this on for 3 years and still no damage. i also asked UR about this and the guy on the phone said he had these on his supra for a few years already and said that the claim that they will cause damage to the engine was BS and his arguement was that they had been in business for 11 years and if it caused damage they would have already closed down. but i dont want this to get into another debate so if someone wants to start a new thread to debate thats fine this is just for people who want to purchase this. I personally only got the accessorys but am now thinking about doing the crank as well.

I can also probably get cam gears from UR if anyone is interested. ill call tomorrow for price

No debating, just facts for potential buyers to look into. On another note, he was driving a 4 banger and I don't think those were dampened from the factory anyhow. Some engine requires dampened pulley and some don't, and there are many things that will determine this. Just a FYI.

[GhostlyEcho]

^^yea i was goin to suggest that jose but its not powdercoating its anodizing on the pulleys it holds better than powdercoating but is a lil more expensive. ok i just called them and they said they discontinued the waterpump pulley. so for the prices are: Set 3 pulleys (crank, aletenator, and power steering) $350 my cost 435 reg
Just two accesory pulleys (altenator and power steering) $205
Seperatly they are 175 Crank
130 power steering
75 alt

discontinued the water pump how gay , Anodizing find out how much to do it for the pulley set and my cam gear

[GhostlyEcho]

No debating, just facts for potential buyers to look into. On another note, he was driving a 4 banger and I don't think those were dampened from the factory anyhow. Some engine requires dampened pulley and some don't, and there are many things that will determine this. Just a FYI.

it's not a fact , its basically hear say about the crank pulleys i have yet to see someone who has had it damage there engine.


It's like the teins, and the bodykits parts like this last depending on how you treat them, these are performance parts and made to work with stock parts. Unless you have own this part eminence or have personally viewed the damage from this pulley i wouldn't say it was a fact, I have seen people talk about it being bad but those are people who have not installed this part on there car and i have also heard from people who have own this part and say there car is fine even with boost. Like he stated above if it was a bad product the company will be out of business just in the amount of refunds and repairs they would have to pay out.


You shouldve bought the titan motorsports one since those are already red. :D

well i got the cam gear off of italianlex way before i even seen the intake that i purchased i didn't even know what color it was till i showed up to faulk2889's house.

[boosted_drew]

discontinued the water pump how gay , Anodizing find out how much to do it for the pulley set and my cam gear

well its 40 per tanks so whatever you can fit in the tank its just a flat rate if there is someone else that wants them red you can split it with them. also a suggestion maybe dumping your strutbar mounts in the tank itll make your bar stand out with a red and chrome theme instead of that black. plus its not extra $
it's not a fact , its basically hear say about the crank pulleys i have yet to see someone who has had it damage there engine.


It's like the teins, and the bodykits parts like this last depending on how you treat them, these are performance parts and made to work with stock parts. Unless you have own this part eminence or have personally viewed the damage from this pulley i wouldn't say it was a fact, I have seen people talk about it being bad but those are people who have not installed this part on there car and i have also heard from people who have own this part and say there car is fine even with boost. Like he stated above if it was a bad product the company will be out of business just in the amount of refunds and repairs they would have to pay out.




well i got the cam gear off of italianlex way before i even seen the intake that i purchased i didn't even know what color it was till i showed up to faulk2889's house.
lol yea the only thing with the cam gear is that the red will cover the black on the gear and idk if itll mess up the adjustment tool on the gear like it might stick it or glue it together.

[boosted_drew]

No debating, just facts for potential buyers to look into. On another note, he was driving a 4 banger and I don't think those were dampened from the factory anyhow. Some engine requires dampened pulley and some don't, and there are many things that will determine this. Just a FYI.

yea i understand i would also like to advise everyone to do research on this and if you do not want the crank i can get you the other 2. although the crank is the biggest gain i personally did not go with it and still debating on it. i started looking into them when my stock power steering pulley was bent so i figure upgrade. and for those of you saying how did it bend i have no clue i bought it like that.

[IS300NA-T]

I just kind of want it because its shiny, Not really any performance reason. ahaha

[boosted_drew]

^^^^lmao shiny does make the engine bay look nicer

[eminence]

yea i understand i would also like to advise everyone to do research on this and if you do not want the crank i can get you the other 2. although the crank is the biggest gain i personally did not go with it and still debating on it. i started looking into them when my stock power steering pulley was bent so i figure upgrade. and for those of you saying how did it bend i have no clue i bought it like that.

The ps pulley, alternator, etc. is irrelevant to the fact. FYI, it is a fact, it's not hearsay. Harmonic balancing was engineered for a reason, and reason being to alleviate the vibration issue. You're correct it is a performance part, but it's not comparable to a body kit or TEINs. Spend some deep time one SupraForums , read on about crankshaft vibration,or talk to any well known tuner they will show you proof. Have you ever heard of SAE? AKA Society of Automotive Engineering. They discuss this issue heavily and in depth and dissapprove of undampened (power pulley).

Are UR product even SFI approved? Any certifications? I am not here to bash this company nor bash on your attempt to help out the community. Whether you think this is the right forum or not to argue this, I think it is. Don't get me wrong UR makes great products, I wouldnt mind rocking their pulley except the crank pulley anyday.


Here is a page explaining "Power Pulley" in depth. Source ATI Performance
Link
http://www.atiperformanceproducts.com/products/dampers/damper_dinan.htm

The Danger of Power Pulleys &
Understanding the Harmonic Damper

BY STEVE DINAN OF DINAN BMW


I have been threatening for a long time to write a series of technical articles to educate consumers and to dispel misconceptions that exist about automotive after-market technology. Motivated by problems with customer's cars resulting from the installation of power pulleys, I wish to explain the potential dangers of these products and address the damage they cause to engines.

The theory behind the power pulley is that a reduction in the speed of the accessory drive will minimize the parasitic losses that rob power from the engine. Parasitic power losses are a result of the energy that the engine uses to turn accessory components such as the alternator and water pump, instead of producing power for acceleration. In an attempt to minimize this energy loss, many companies claim to produce additional power by removing the harmonic damper and replacing it with a lightweight assembly. While a small power gain can be realized, there are a significant number of potential problems associated with this modification, some that are small and one which is particularly large and damaging!

The popular method for making power pulleys on E36 engines is by removing the harmonic damper and replacing it with a lightweight alloy assembly. This is a very dangerous product because this damper is essential to the longevity of an engine. The substitution of this part often results in severe engine damage.
It is also important to understand that while the engine in a BMW is designed by a team of qualified engineers, these power pulleys are created and installed by people who do not understand some very important principles of physics. I would first like to give a brief explanation of these principles which are critical to the proper operation of an engine.

1) Elastic Deformation
Though it is common belief that large steel parts such as crankshafts are rigid and inflexible, this is not true. When a force acts on a crank it bends, flexes and twists just as a rubber band would. While this movement is often very small, it can have a significant impact on how an engine functions.

2) Natural Frequency
All objects have a natural frequency that they resonate (vibrate) at when struck with a hammer. An everyday example of this is a tuning fork. The sound that a particular fork makes is directly related to the frequency that it is vibrating at. This is its "natural frequency," that is dictated by the size, shape and material of the instrument. Just like a tuning fork, a crankshaft has a natural frequency that it vibrates at when struck. An important aspect of this principle is that when an object is exposed to a heavily amplified order of its own natural frequency, it will begin to resonate with increasing vigor until it vibrates itself to pieces (fatigue failure).

3) Fatigue Failure
Fatigue failure is when a material, metal in this case, breaks from repeated twisting or bending. A paper clip makes a great example. Take a paper clip and flex it back and forth 90° or so. After about 10 oscillations the paper clip will break of fatigue failure.

The explanation of the destructive nature of power pulleys begins with the two basic balance and vibration modes in an internal combustion engine. It is of great importance that these modes are understood as being separate and distinct.

1) The vibration of the engine and its rigid components caused by the imbalance of the rotating and reciprocating parts. This is why we have counterweights on the crankshaft to offset the mass of the piston and rod as well as the reason for balancing the components in the engine.

2) The vibration of the engine components due to their individual elastic deformations. These deformations are a result of the periodic combustion impulses that create torsional forces on the crankshaft and camshaft. These torques excite the shafts into sequential orders of vibration, and lateral oscillation. Engine vibration of this sort is counteracted by the harmonic damper and is the primary subject of this paper.

Torsional Vibration (Natural Frequency)

Every time a cylinder fires, the force twists the crankshaft. When the cylinder stops firing the force ceases to act and the crankshaft starts to return to the untwisted position. However, the crankshaft will overshoot and begin to twist in the opposite direction, and then back again. Though this back-and-forth twisting motion decays over a number of repetitions due to internal friction, the frequency of vibration remains unique to the particular crankshaft.

http://www.atiperformanceproducts.com/products/dampers/dinan/image2.jpg

This motion is complicated in the case of a crankshaft because the amplitude of the vibration varies along the shaft. The crankshaft will experience torsional vibrations of the greatest amplitude at the point furthest from the flywheel or load.





Harmonic (sine wave) Torque Curves
Each time a cylinder fires, force is translated through the piston and the connecting rod to the crankshaft pin. This force is then applied tangentially to, and causes the rotation of the crankshaft.

The sequence of forces that the crankshaft is subjected to is commonly organized into variable tangential torque curves that in turn can be resolved into either a constant mean torque curve or an infinite number of sine wave torque curves. These curves, known as harmonics, follow orders that depend on the number of complete vibrations (cylinder pulses) per revolution. Accordingly, the tangential crankshaft torque is comprised of many harmonics of varying amplitudes and frequencies. This is where the name "harmonic damper" originates.




http://www.atiperformanceproducts.com/products/dampers/dinan/image3.jpg


Critical RPM's
When the crankshaft is revolving at an RPM such that the torque frequency, or one of the harmonic sine wave frequencies coincides with the natural frequency of the shaft, resonance occurs. Thus, the crankshaft RPM at which this resonance occurs is known a critical speed. A modern automobile engine will commonly pass through multiple critical speeds over the range of its possible RPM's. These speeds are categorized into either major or minor critical RPM's.

Major and Minor Critical RPM’s
Major and minor critical RPM's are different due to the fact that some harmonics assist one another in producing large vibrations, whereas other harmonics cancel each other out. Hence, the important critical RPM’s have harmonics that build on one another to amplify the torsional motion of the crankshaft. These critical RPM’s are know as the "major criticals". Conversely, the "minor criticals" exist at RPM's that tend to cancel and damp the oscillations of the crankshaft.

If the RPM remains at or near one of the major criticals for any length of time, fatigue failure of the crankshaft is probable. Major critical RPM’s are dangerous, and either must be avoided or properly damped. Additionally, smaller but still serious problems can result from an undamped crankshaft. The oscillation of the crankshaft at a major critical speed will commonly sheer the front crank pulley and the flywheel from the crankshaft. I have witnessed front pulley hub keys being sheered, flywheels coming loose, and clutch covers coming apart. These failures have often required crankshaft and/or gearbox replacement.

http://www.atiperformanceproducts.com/products/dampers/dinan/pully_wp.jpg

Harmonic Dampers
Crankshaft failure can be prevented by mounting some form of vibration damper at the front end of the crankshaft that is capable of absorbing and dissipating the majority of the vibratory energy. Once absorbed by the damper the energy is released in the form of heat, making adequate cooling a necessity. This heat dissipation was visibly essential in Tom Milner's PTG racing M3 which channeled air from the brake ducts to the harmonic damper, in order to keep the damper at optimal operating temperatures. While there are various types of torsional vibration dampers, BMW engines are primarily designed with "tuned rubber" dampers.




It is also important to note that while the large springs of a dual mass flywheel absorb some of the torsional impulses conveyed to the crankshaft, they are not harmonic dampers, and are only responsible for a small reduction in vibration.

In addition to the crankshaft issue, other problems can result from slowing down the accessories below their designed speeds, particularly at idle. Slowing the alternator down can result in reduced charging of the battery, dimming of the lights, and computer malfunctions. Slowing of the water pump and fan can result in warm running, while slowing of the power steering can cause stiff steering at idle and groaning noises. It is possible to implement design corrections and avoid these scenarios, but this would require additional components and/or software.
Our motto at Dinan is "Performance without sacrifice" We feel our customers expect ultra high performance along with the legendary comfort and reliability of a standard BMW.

While it is common that a Dinan BMW is the fastest BMW you can buy, performance is not our only goal. Dinan isn't just trying to make the fastest car. Instead a host of considerations go into the development of our products. Dinan puts much more effort into these other areas than does our competition.
These considerations are Performance, Reliability (Warranty), Driveability, Emissions, Value, Fit and Finish. We feel that the power pulley is a bad way to get extra power from and engine and the potential for serious engine damage is too great.

This is a simplified explanation meant to be comprehensible by those who are not automotive engineers. In trying to simplify an extremely complex topic some precision was sacrificed although we believe this explanation to be as accurate as possible. We encourage our customers to educate themselves and understand the automotive after-market because we believe that our products are the best researched, engineered, and fabricated products available.

For those interested in a more in depth and technical explanation of this topic, the reference book is Advanced Engine Technology, written by Heinz Heisler MSc,BSc,FIMI,MIRTE,MCIT. Heinz Heisler is the Head of Transportation Studies at The College of North West London. His book is distributed in this country by the SAE (Society of Automotive Engineers).

[maxlmus347]

^^^ you win!

[GhostlyEcho]

:lee: ur just beating this thread down with a debate if people are going to buy it there going to buy it, i have never heard of someone having it and there engine going bad.

[eminence]

:lee: ur just beating this thread down with a debate if people are going to buy it there going to buy it, i have never heard of someone having it and there engine going bad.

Okie dokie smokie! Nothing to debate, what I spit out are all facts and proven theories. Being a mechanical engineer student, I am more knowledgable with the physics stuff then most in this thread so I understand the circumstances. Buy what you want, do what you feel. This is a public forum, I decide to pointed out the fact so that those who are considering the product might what to think and research further.

Again, remember these are FACTS not hearsay. The write up I just posted was from an engineer from Dinan Motorsports, well known in the BMW world. Secondly, what he stated are just reiteration of what physics and well known engineers had studied for years. But what do they know!


Good luck

[Inspar8r]

Dinan is also well known in the community for being way overpriced for the wussy ass gains you get, but there is validity to what he points out.

That said, all I can say is that I wouldn't recommend underdriving the alternator. It already is underpowered at 13.7V (most cars are 14.4). Nothing irritated me more on my BMW than dimming lights while at an idle. Thats the only experience I had with underdrive stuff.

Eminence is looking out for the community's best interest like the OP is providing a product at good prices. Me personally, I can get better auto-x/road course gains spending $300 elsewhere, plus, I just don't feel like replacing pulleys. I remember how much it sucked when I did it on the bimmer.

[Phillzpeed]

Eminence is not just whistling dixie here people. There have been many proven instances of issues caused by Underdriven crank pulleys. There have, also, been many success stories and many Supra owners that absolutely love theirs. But the fact is that when you replace a dampened, harmonically balanced rotational part with an undampened one, you are taking a chance.

That being said, they rest of the pulleys are hella nice! The rest are all stock size and not underdriven. They are lighter than stock, so their is some weight savings which can translate in slight HP gains. And they are damn pretty!

I did not use the UR underdrive crank pulley (which is for sale if anyone is interested!), and went with an ATI Super Damper since I will be putting out very high HP numbers. I would just rather play it safe.

Here are some pics of how fricken nice they are...

http://i8.photobucket.com/albums/a16/Phillzpeed/Motor%20Build%20pics/Motor007.jpg

http://i8.photobucket.com/albums/a16/Phillzpeed/Motor%20Build%20pics/Motor012.jpg

http://i142.photobucket.com/albums/r120/SPIN2GST/DSCN1105.jpg

[stjarvis]

On an automatics wouldn't the torque conveter do a significant amount to harmonically dampen the engine? Just a thought but since it's full of transmission fluid and pretty well connected to the crank via the flex plate.

[-Tom-]

!980's and early 90's chrysler 2.2 and 2.5L engines do NOT use a crank dampener of any kind nor do they use balance shafts. Those engines are widely regaurded as bullet proof in terms of long term durability and power retention.....

I'm SURE toyota does a better job balancing the engine than chrysler did back in the day. now a perfectly balanced UD pulley agreeably would not dampen vibration BUT it wont actually harm the engine its self. a slightly and I mean 2-3 grams slightly out of balance clutch will do FAR more damage to an engine than a under drive pulley....just providing the other point of view. The underdrive pulley just unmasks the current state of the engine. If you already have an engine thats out of balance to the manufacturers maximum tolerances and a clutch thats out of balance to max tolerance and crank bearings that are sloppy to max spec you end up with an engine that IS with in spec but it still in rough shape, an engine like that WOULD benefit very much from a dampener. HOWEVER my neon race engine is balanced perfectly across the cylinders and the crank/clutch/underdrive assembly is balanced with in .0058 grams. The bearing tolerances are all right in the middle of the manufacturer tolerances. THAT is an engine that will suffer ZERO harm from an under drive......

[BernieIS]

Okie dokie smokie! Nothing to debate, what I spit out are all facts and proven theories. Being a mechanical engineer student, I am more knowledgable with the physics stuff then most in this thread so I understand the circumstances. Buy what you want, do what you feel. This is a public forum, I decide to pointed out the fact so that those who are considering the product might what to think and research further.

Again, remember these are FACTS not hearsay. The write up I just posted was from an engineer from Dinan Motorsports, well known in the BMW world. Secondly, what he stated are just reiteration of what physics and well known engineers had studied for years. But what do they know!


Good luck

Anyone that does not take heed to his statements which are factual is asking for trouble. If you are intereted in the group buy go ahead and get what you want. My recommendation would be to get the power steering and a/c pullies and then get the ATI dampened and harmonically balanced crank pully.

Dinan is also well known in the community for being way overpriced for the wussy ass gains you get, but there is validity to what he points out.

That said, all I can say is that I wouldn't recommend underdriving the alternator. It already is underpowered at 13.7V (most cars are 14.4). Nothing irritated me more on my BMW than dimming lights while at an idle. Thats the only experience I had with underdrive stuff.

Eminence is looking out for the community's best interest like the OP is providing a product at good prices. Me personally, I can get better auto-x/road course gains spending $300 elsewhere, plus, I just don't feel like replacing pulleys. I remember how much it sucked when I did it on the bimmer.


The cost of Dinan aftermarket upgrade parts is not the issue. The issue is that there is a group buy available to us and one of the items in that group buy could possible damage our vehicles, which Eminence has done a fabulous job researching and conveying these facts to us.

Also from my experience aroung car audio and some of the most well know car audio people in the Pittsburgh area(originally from there) most cars never reach more than 12V. That is why the shops at Circuit City and Best Buy call themselves the 12 volt department. In all actuallity you can run the alternator pulley safely, many people have done so.

[boosted_drew]

ok im back from conneticut and i see alot of activity on this page so im gonna chim in on some stuff.

That being said, they rest of the pulleys are hella nice! The rest are all stock size and not underdriven. They are lighter than stock, so their is some weight savings which can translate in slight HP gains. And they are damn pretty!

I did not use the UR underdrive crank pulley (which is for sale if anyone is interested!), and went with an ATI Super Damper since I will be putting out very high HP numbers. I would just rather play it safe.

I have read alot about this and that was my original set up attempt. but is the ATI a power gain upgrade or strictly for safety? also how much did it cost and where are they located maybe i can set up an account with them as well.

[QUOTE=BernieIS;93239]Anyone that does not take heed to his statements which are factual is asking for trouble. If you are intereted in the group buy go ahead and get what you want. My recommendation would be to get the power steering and a/c pullies and then get the ATI dampened and harmonically balanced crank pulley.

The cost of Dinan aftermarket upgrade parts is not the issue. The issue is that there is a group buy available to us and one of the items in that group buy could possible damage our vehicles, which Eminence has done a fabulous job researching and conveying these facts to us.

Also from my experience aroung car audio and some of the most well know car audio people in the Pittsburgh area(originally from there) most cars never reach more than 12V. That is why the shops at Circuit City and Best Buy call themselves the 12 volt department. In all actuallity you can run the alternator pulley safely, many people have done so.

Yea i have never experienced a problem withmy alt pulley and i have a system in my car so its pretty safe to me

[eminence]

I am glad that you have a medium in your opinion, that will be a characteristic I will more then likely appreciate in a forum. Many folks like to be hard headed and firm with their opinion and it tend to lead to big time bashing.

For more information about the ATI pulleys and/or their available products please check out their website

www.atiperformanceproducts.com

[boosted_drew]

I am glad that you have a medium in your opinion, that will be a characteristic I will more then likely appreciate in a forum. Many folks like to be hard headed and firm with their opinion and it tend to lead to big time bashing.

For more information about the ATI pulleys and/or their available products please check out their website

www.atiperformanceproducts.com

yea i am not hard headed i know that there are many people on this forum that know alot more than me. i joined to further my knowledge of my car. I only started this group buy because i wanted to help out other members like I have been helped. so if they would rather just have the accessory pulleys which is almost impossible to buy without buying the whole set i can get it. and if you have researched the crank pulley and decide that you want it I can get it. just tryna help out like i have been helped out

[Phillzpeed]

yea i am not hard headed i know that there are many people on this forum that know alot more than me. i joined to further my knowledge of my car. I only started this group buy because i wanted to help out other members like I have been helped. so if they would rather just have the accessory pulleys which is almost impossible to buy without buying the whole set i can get it. and if you have researched the crank pulley and decide that you want it I can get it. just tryna help out like i have been helped out

More people need to have your mentality. These are very nice items indeed, whether or not you decide to use the crank pulley.

+rep

[Inspar8r]

The cost of Dinan aftermarket upgrade parts is not the issue. The issue is that there is a group buy available to us and one of the items in that group buy could possible damage our vehicles, which Eminence has done a fabulous job researching and conveying these facts to us.


I am aware of this, however, I ALWAYS consider the source. In this case, I was reinforcing what eminence was posting. Dinan isn't a company that exceeds or pushes the limits of auto tuning. They make expensive shit that gives you mild gains in order to preserve the warranty of the vehicle. Even the parts modified.


Also from my experience aroung car audio and some of the most well know car audio people in the Pittsburgh area(originally from there) most cars never reach more than 12V. That is why the shops at Circuit City and Best Buy call themselves the 12 volt department. In all actuallity you can run the alternator pulley safely, many people have done so.

You have much to learn (which we're all doing in this thread anyway). When cars in running, the alternator puts out higher voltages. It's called dynamic power which generally ranges from 13.7 to 14.4 volts. Each electrical component within the car has it's own 12 volt (or 5v regulator anyway, so the fluctuations don't matter much).

If you'd like, I'll go measure the voltage on the car while it's started, and snap a pic.

In fact, in a nominally charged battery, the voltage will read 12.6V because each of the 6 galvanic cells inside a battery are 2.1V.

As for the best buy and everything, it's for recognition purposes. The assumption is that cars run off of 12V, which is true, but it is not an exact 12, as I just explained. There is much more to it. People wouldn't know what the hell a 13.7V dept or a 14.4V dept would look like.

Underdriving is not done as much as it used to. The thread is not about under driving, it's about lightweight pulleys. This will have 0 effect on the charging system. As for underdriving, that is what I did years back in my bimmer. The pulley had a clutch like system to it, reducing the drag required the spin the alternator.

[JahnIS300]

BtW does anyone know what the diameter for our crank pulley is?? Been searching for this info for ages!

[RaptorV1]

Okie dokie smokie! Nothing to debate, what I spit out are all facts and proven theories. Being a mechanical engineer student, I am more knowledgable with the physics stuff then most in this thread so I understand the circumstances. Buy what you want, do what you feel. This is a public forum, I decide to pointed out the fact so that those who are considering the product might what to think and research further.

Again, remember these are FACTS not hearsay. The write up I just posted was from an engineer from Dinan Motorsports, well known in the BMW world. Secondly, what he stated are just reiteration of what physics and well known engineers had studied for years. But what do they know!


Good luck


My research over two years ago turned up the same and similar articles... my on line forum cruising showed the typical: many folks spouting off what they read or heard but not alot of people who actually tried it... at all Vs. long term...

IMO the problems these cause are not seen immediately but mroe long term... basically the wear & tear they alow shortens bearing / crank & motor life... but often in a motor whos owner does this upgrade.. .they also have many others & more often than not some OTHER problem comes along & might interfere with the proper diagnosis of these having been an issue at all.......

Regardless, of the few who said they had seen them in use long term no problem, or used them long term themselves with no problem, No one ever claimed that running the crank pulley provided a real noticeable benefit at all much less with no discernable increase in motor bearing wear & tear etc...

IMO Steve Dinan knows his shit ...& he is not the only person to use the same basic argument as to why undampened crank pulleys are an unwise modification if you care abot the longevity of your motor ESPECIALLY if you really drive it hard...

I am tired of replacing motors.

I feel that I beat my motor much harder than the average owner Lexus focused on with this car... the entire structure is more stressed & i use it MUCh harder than average...with the SC much less my driviing... the motor is more stressed & naturally has a shorter life span than if I was a cruiser... therefore, with no real performance benefit to the part or so little that it was negligible in the long run andthe chance of a problem......why bother? the money spent there can go into something more enjoyable or noticeable or what not...... the bank!?

Eminence is not just whistling dixie here people. There have been many proven instances of issues caused by Underdriven crank pulleys. There have, also, been many success stories and many Supra owners that absolutely love theirs. But the fact is that when you replace a dampened, harmonically balanced rotational part with an undampened one, you are taking a chance.

Philzpeaks...;) THat is it bottom line & for what?


if ya gotta replace a pulley go with a high quality Dampened one...


I hear there is a high quality Alloy light weight Dampened(!!) one for the 2jz from a co. called Ross in Australia... I am looking onto it...


for now...I went with the ATi as well, great minds...;)


PS:... I run all 4 of the other UR Pulleys... I got them before they stopped making the water pump & they came in blue ano also...;)

[Inspar8r]

Moved the info here so as to not cramp the style of the GB thread.