STILLEN Lightweight Pulleys - Introductory Offer!

[RobPaulson]

This is the same concept of gains that I was referring to in #2 of my post above.

dont know how i missed that . . . doh!

[dangeris]

HAHA I almost had a heart attack!! After talking to ya it sounded awesome then I read this first line and almost fainted! Anyway, glad to see the write up-- I'm gonna have to put in for one of these soon.

Oh, you need to tell folks what you thought about the steering wheel/accessories...

Good Point! After reading the thread, I otice people were stating that they felt a difference in their PS so I made it a point to "mentally note" that. After the install, i could not feel the difference in the steering, at idle or while driving around. Water temp has stayed the same and I know this because I monitor that during the winter with my ScanGuageII. No reported anomaly on that. Can't remark on the air condtioner since it's still cold out but I would suspect that the install of the UD Pulley will have no adverse affect on AC performance either.

[Boilermaker318]

This would be a good use of tax refund money to stimulate the economy but I only have two days to decide to get the reduced price! Tough choices.

[unknow]

hey,I'm very interested to get STILLEN Lightweight Pulley for my 08 alti 2.5.But what do you think guys which one will give you more gains Lightweight Pulley, exhaust or Intake?

[LongBeachCoupe]

Hey guys, sorry I havent installed the pulley for the 2.5ers yet...

I kinda dropped the ball on this one... my bad.

I moved on 2/14 and then started a new business which has got me working like 12 hrs a day (big change from being unemployed)...

Tomorrow I should be getting it put on and I will post my honest impressions..

Max, one of these "quant jocks" (what finance people call the real number crunchers) will come in here and break it down for you, but dealing with rotating mass in high speed situations, something lighter will most certainly change the output...

Think of the energy required for a washing machine to spin with towels in it, and then the energy required if it were empty, acceleration of a significantly lighter mass is something VERY quantifiable to someone with the right brain power...

Theres quite a few guys on here than have mechanical engineering degrees I believe... someone get the numbers together and prove this out on paper!

[Team STILLEN]

LBC is back! LOL.. I bet there is smoke spewing from his keyboard and mouse trying to catch up..

[LongBeachCoupe]

LBC is back! LOL.. I bet there is smoke spewing from his keyboard and mouse trying to catch up..

Dude you have no idea how busy I am now... with coupons of all things!

Seriously though, I thought I was going to get the net back, and have all issues etc.... and while I was gone its like they began filming a NICO Girls Gone Wild video!

Wheres the QUANT-JOCK that can break this down mathematically??

[michaelthepsycho]

So... I just got the car back from the shop and I'll have to say I get 60,65 mph at sub-2k rpm. Just a thought. I can't really say if it got fast"er" but it's definitely fast to me. On smooth roads, I'm constantly at 20,30 over the speed limit and only slow down when I see police... So yeah, in general, got to give the light weight pulley a positive thumbs up

[guitarist982]

So... I just got the car back from the shop and I'll have to say I get 60,65 mph at sub-2k rpm. Just a thought. I can't really say if it got fast"er" but it's definitely fast to me. On smooth roads, I'm constantly at 20,30 over the speed limit and only slow down when I see police... So yeah, in general, got to give the light weight pulley a positive thumbs up

What is your post even saying? What does a pulley have to do with driving over the speed limit?

[michaelthepsycho]

Easier to go over with just a little tap.

[Ferguson]

After a bit of a delay (not Stillen's fault - other backordered items in the order), my underdrive pulley arrived today. Now I have a problem. I don't know whether to install it on the car or hang it on the wall as a piece of art! Unless you get the chance to hold one in your hands, you can't appreciate how beautifully made these really are. I probably won't get mine on until late April when the weather gets more 'install friendly' around here, but I'm not packing it away in the box... this thing is on display!

Yeah... okay... if we get a couple of warm days on one of my weekends.... it's going on... I'm dying to run some acceleration 'before and after' times!

[maxentropy]

I'm dying to run some acceleration 'before and after' times!

That'd be great and let us know how the steering/electronics feel before and after too!

[08coupedaddy]

so i was wondering if anyone has installed this yet on the 3.5 CVT yet? Just wondering if it had the same or similar gains as the MT. I have noticed when i am in sport shift and take off from a stop in first it takes a little bit to sort of get into a "power band" and was wondering if the pulleys would make it accelerate alot faster even for the CVT? Thanks so much

[EzeebMOS3]

I just want to make sure that by installing this on my 3.5 CVT it will have no problems with the accessories, short term and long term. I don't want my power steering pump to fail after a year and a half or something to that nature.

[Ferguson]

It won't! Accessories and things like power steering, brakes, etc. are factory overdriven to allow headroom for the guys that put 4000W stereos into their cars. 20% underdrive is meaningless if you haven't added stuff like that which draws major current. If you HAVE added major amp-sucking components, then, yes, you need to consider that before going to an underdrive unit. Only a very few people are going to ever feel the loss - and it won't destroy the equipment anyway.

[felv8]

Did anyone have any problems during the DIY install? I couldn't get the 19mm center pulley bolt off for the life of me, even with an impact wrench! So I gave up and took it in to the shop this morning. Anyone else run into this problem? It's like they put a jar of loctite on that bolt.. ridiculous

[AppleBonker]

Theres quite a few guys on here than have mechanical engineering degrees I believe... someone get the numbers together and prove this out on paper!

Guess no one wants to jump on this one, so I'll give it a go. Unfortunately, these are all estimates and will only give a rough idea. Been a while since I've had to do this, so someone correct me if I'm wrong.

First, the assumptions:

1. Let's call the pulley an open cylinder with all of its mass on the outer edge (think of a piece of paper rolled into a cylinder), as this is a close estimate to the pulley (which has most of its mass near the outer edge).

2. Angular acceleration is constant (IE, the time it takes for the engine to go from 2,000 RPMs to 4,000 RPMs is the same as from 4,000 RPMs to 6,000 RPMs).

3. Since I don't have a pulley (and don't really want to do the work with the actual dimensions), let's say it has a radius of 2.5 inches (we'll use the Stillen-measured weight of 4.71/1.10 lb respectively).

Equations:

I = m * r^2where 'I' is moment of inertia (lb*ft^2 - I'll use the notation Io for stock and Is for the Stillen pulley), 'm' is mass (lb) and 'r' is the radius of the pulley (ft)

T = I * awhere 'T' is torque (lb*m^2*sec^-2 - again using To and Ts) and a is angular acceleration (radians*sec^-2)

OK, the fun part:

Io = 4.71*(2.5/12)^2 = 0.2044 lb*ft^2Is = 1.10*(2.5/12)^2 = 0.0477 lb*ft^2

Now, say we want to run the engine from 1,000 RPM (roughly idle) up to 6,000 RPM (roughly redline) in 2 seconds. That is a difference in velocity of 5,000 RPMs. converting this to seconds gives us 83.33 rotations per second difference. Next, we need to convert to the units above to be able to use the equations. 1 rotation = 360 degrees = 2*pi radians, so an increase of83.33 rotations per second is an increase of 523.598 radians per second. Now, divide this by the time consumed in the process to get the angular acceleration:

523.598 / 2 = 261.799 radians per second squared (rad*sec^-2)

Ok, put the two together:

To = 0.2044 * 261.799 = 53.51 lb*ft^2*sec^-2Ts = 0.0477 * 261.799 = 12.49 lb*ft^2*sec^-2

Now, keep in mind the pound-foot of torque measured for the car is equal to the force a one pound object would exert at a distance of one foot from the pivot point. The estimate for gravitational force is 32.2 ft/sec^2 so:

1 lb-ft = 1lb * 32.2ft/sec^2 *1ft = 32.2 lb*ft^2*sec^-2

Using the torque determined above and this conversion value:

To = 1.66 lb-ftTs = 0.39 lb-ft

There you have the difference in torque (roughly) that is being consumed by the pulley. It may look minimal in comparison to the rated torque output at the crank, but think of how much is lost before hitting the pavement (not to mention how much force is needed to overcome rolling friction and wind resistance), and this becomes more critical. Also, realize that at 1,000 RPMs the engine is certainly not putting out peak torque, so percentage-wise this becomes more important.

Again, keep in mind the assumptions that I made (to make calculations a bit simpler). The numbers may look trivial, but if you factor everything in, they begin to appear more substantial.

My head hurts...

[AppleBonker]

Let me also point out that the underdrive pulleys will have an even more reduced moment of inertia (they are lighter and have a smaller radius), so the gains will be even bigger.

Remember these are rough estimates, so please don't base your decision of buying a pulley or not on these numbers alone (again, since they are not perfectly accurate). Let's face it, the guys at Stillen know more about cars than most of us, and I haven't seen them put out products that are worthless just to snag money from us. Just my two cents...

And to save you all the time: sure, I am a nerd

[Marisha]

Thanks for the number crunching

[EzeebMOS3]

I just got the pulley installed on my 3.5 CVT a few hours ago. First thing, there is no difference in the steering practically at all, only when you're not moving do you notice the steering to be a bit stiff. Whether or not this part has made any improvements is interesting. I did get a chance to drive around and I can say the car "feels" faster. The car seems more responsive, meaning that when I gas the pedal, there is less time spent spooling up the RPMS kind of minimizing that delay the CVT has. Overall I think it is a good mod. I did not notice any problems with the stereo or headlights (500Watt amp 10" sub stock NAV).

PROS: More responsive + more efficient

I'm going to take a few vids later tonight and should have them on youtube later on tonight for you guys. I always like to see vids before i purchase a mod.

[G_whizz]

Who came first?

Great logic!

E.Stoiber

Clearly you are here to troll...

Oops...I just hit the BAN button

[RobPaulson]

Clearly you are here to troll...

Oops...I just hit the BAN button

ugh thank you . . .

wow epic moderation

[G_whizz]

[LongBeachCoupe]

Bleeding woulda stopped faster if i had that ban button on my keyboard... its not there though!

Clearly you are here to troll...

Oops...I just hit the BAN button

[spockrock]

I realize it may not seem to make sense on how lightening by 3lbs can make a difference, but it's rotating mass, that's different than simple weight.

I'll give you an example. We have a supercharged Titan here on 24" wheels. For shows or demos, we put the stock Titan wheels back on. That nets 40hp to the wheels because of the rotating mass and difference in weight. I'm not saying that this pulley gets anywhere near this, but the weight of the wheels and tires themselves has to be spun by the driveline, just like the pulley.

And if we're overcharging for the belt, which is expensive, it's a full serpentine, and it's a quality Gates belt, simply use your stock belt, and/or see if you can find it for a better price, the part number is K060878. We have them in stock, and it ships for free with the pulley. Beware though, most claim to have every belt in stock, but don't.

It think it's been shown time and again that we supply you guys with quality parts at extremely competitive prices, not sure why you would think thigns were different now..

That is a completely unfair comparison you are comparing unsprung weight to sprung weight. The wheels are unsprung, meanwhile the pulley is sprung weight. Lowering unsprung weight has more benefit then lowering the sprung weight. Even it is rotational mass we are speaking about.

We aren't questioning the quality of the product, or stillen, we are just saying that the gains from a lightened pulley are not worth while. Lightened pulleys at best are 'magic beans' the fact that you sell quality magic beans does not mean change the fact its still magic beans.

[EliteGTR]

We aren't questioning the quality of the product, or stillen, we are just saying that the gains from a lightened pulley are not worth while. Lightened pulleys at best are 'magic beans' the fact that you sell quality magic beans does not mean change the fact its still magic beans.

LOL. You have no idea what you're talking about. You obviously have no experience with pulleys. Not only are they beneficial but in most cases offer better performance gains then other bolt on products. Such as intakes or exhaust at a much cheaper price.

[LongBeachCoupe]

Address the numbers applebonker crunched to refute it... not just making a claim.

I am a numbers guy, if you can show it to me in numbers, ill believe it. "The gains are not worthwhile"? So you are admitting theres a gain.

[RobPaulson]

We aren't questioning the quality of the product, or stillen, we are just saying that the gains from a lightened pulley are not worth while. Lightened pulleys at best are 'magic beans' the fact that you sell quality magic beans does not mean change the fact its still magic beans.

LOL the gains from a pulley are so hard to comprehend that you are using an analogy to a magic bean??

well let me tell you, its no magic bean, get some technical/scientific education and you'll quickly understand what a HUGE benifit this pulley can be. Or just look at the numbers bunker posted, as a fellow engineer i can tell you hes right.

[maxentropy]

Indeed, Rob.

Apple, thanks for the numbers. Looks great-- and one would expect better gains from a 3.5 if you are replacing the current pulley. I am assuming that your math was based on that and not the 2.5 swap. It's sunday so go easy...

[dldjros69]

Indeed, Rob.

Apple, thanks for the numbers. Looks great-- and one would expect better gains from a 3.5 if you are replacing the current pulley. I am assuming that your math was based on that and not the 2.5 swap. It's sunday so go easy...

I love how you hate the 2.5 pulley, i laugh every time.