STILLEN Lightweight Pulleys - Introductory Offer!

[dangeris]

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

Yeah,..Max is just a hater booooo, booooooo

[spockrock]

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.

I am talking about lightened pulleys not under drive pulleys, I have from day one said underdrive pulley is the best mod to get. So before you suggest you I don't know what I am talking about I have read the math and science behind and as well as a degree in engineering.

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.

I always said the gains from a light weight pulley are only good for 1~2 HP in first gear. I have admitted that there are gains but not significant gains on 2.5 worth the money.

I won't refute applebonker because he has shown exactly what I have been saying.

The only point of contention with his assumption is that he uses an open cylinder as for calculating inertia, I would think the pulley is a mix from what I can see thick walled cylinder and a flat disk.

The without rewriting all the work here is the difference for flat disk;

Io= 0.1022Is=0.02385 ~ 0.0239

Therefore

To=26.76Ts=6.26

after factoring gravity

To=0.831Ts=0.194

Now since a pulley is neither a hallow cylinder nor a flat disc you are looking at somewhere in between realistically if we had a pulley, and we had the inner and out diameter of the pulley, the best equation to use is cylinder with thick wall which is (I = 1/2M* (R1^2 +R2^2)) and you would seen see that that the potential gain is even less if you guys would like to tell me what the inner diameter or the wall thickness is and I can give you a more accurate numbers. If I assume that the outer diameter is still 2.5 and that the wall thickness is about a 1/4 inch (inner radius is 2.25) then what you get for To, is 1.504 and Ts is 0.702.

Either way the gains are right in line with what I have stated before 1~2HP/TQ. Gains are not worth it in my opinion, which is what I have always stated. Unless you want to show me dyno and quarter miles that say otherwise.

The 3.5 UDP is worth every penny and then some.

[michaelthepsycho]

I think it comes down to dollar-to-hp gain. $150 for let's say 2 hp is in the approximate range of a turbo upgrade ($7500 for say 100 hp), not to mention the low individual cost / hassle-less installation process.

[spockrock]

I think it comes down to dollar-to-hp gain. $150 for let's say 2 hp is in the approximate range of a turbo upgrade ($7500 for say 100 hp), not to mention the low individual cost / hassle-less installation process.

You make a good point, all I wanted was people to do is make an informed decision, don't expect the same gains a 3.5. I know people want lightened pulleys and companies will sell them.

Just so there is more info to digest;



Above is a dyno of a lightened pulley stock diameter from 6.24 LBS to 2.04LBS, about 67% weight reduction on a g35. As you can see the gains are hardly noticable.
Modified by spockrock at 4:59 AM 4/8/2009

[EliteGTR]

Sure, gains in performance will vary from car to car. With pulleys its not about total horsepower gain. You have to look at the whole run. If you look at the chart you will notice some good pickup in power in the low to mid range. Also the car will see improved gas mileage and accelerate quicker.

Also the chart you posted only shows the pulley vs the airbox not a baseline run.

[spockrock]

Sure, gains in performance will vary from car to car. With pulleys its not about total horsepower gain. You have to look at the whole run. If you look at the chart you will notice some good pickup in power in the low to mid range. Also the car will see improved gas mileage and accelerate quicker.

Also the chart you posted only shows the pulley vs the airbox not a baseline run.

Sorry I know the dyno is not clear but that air box run is before and the KJR Pulley is from the second pull after the pulley was installed.

These are the before and after mods, as you can see the only change is the LW pulley.

BeforeZ-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200250.36 HP _ 229.12 FT-LB

AfterZ-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200, KJR LW Pulley250.49 HP _ 229.73 FT-LB

The user did say the car pull harder from 40 -120, but that's butt dyno.

[maxentropy]

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

Please note the two nerds above that so beautifully made my point.

You just get excited everytime I say 2.5!

[Ferguson]

Just got the underdrive 3.5 pulley installed (thanks to my son) and there is no doubt that this is a performance mod that is worthwhile to a 3.5 owner! The engine definitely revs quicker and the car pulls harder. I promised some comparison times, and I have the 'before' times, but it has just snowed here again and I can't run the 'after' times yet. But my gut feel on the one partial clear day I had is that the 0-120 km/h (0-75 mph) times will drop by at least .3 second.

The underdrive has also shown no impact on any of my systems - steering, A/C, etc. all work as before with absolutely no perceptible change. I see no difference at all in the operation of any pulley driven system.

Installation (almost exactly as documented by Dangeris) was a breeze, except for one thing. As mentioned by others, getting the pulley bolt off was a test! We broke one 19mm socket in the process. I would recommend using an impact grade socket with a high-quality breaker bar to get that sucker off!

But, all in all... I give the 3.5 pulley

[mrodrig2]

I'm not going to argue either way, but note that you have the %-reduction reversed. 6.24lb down to 2.04 lbs is approx 67% reduction, not 33%.

[spockrock]

Just got the underdrive 3.5 pulley installed (thanks to my son) and there is no doubt that this is a performance mod that is worthwhile to a 3.5 owner! The engine definitely revs quicker and the car pulls harder. I promised some comparison times, and I have the 'before' times, but it has just snowed here again and I can't run the 'after' times yet. But my gut feel on the one partial clear day I had is that the 0-120 km/h (0-75 mph) times will drop by at least .3 second.

The underdrive has also shown no impact on any of my systems - steering, A/C, etc. all work as before with absolutely no perceptible change. I see no difference at all in the operation of any pulley driven system.

Installation (almost exactly as documented by Dangeris) was a breeze, except for one thing. As mentioned by others, getting the pulley bolt off was a test! We broke one 19mm socket in the process. I would recommend using an impact grade socket with a high-quality breaker bar to get that sucker off!

But, all in all... I give the 3.5 pulley

I want the 3.5 pulley but the misses would tear me a new one if I spent more money on my car.

I'm not going to argue either way, but note that you have the %-reduction reversed. 6.24lb down to 2.04 lbs is approx 67% reduction, not 33%.

Oops you are right.
Modified by spockrock at 4:59 AM 4/8/2009

[Ranga14]

Looks like it might be worth it, just unsure.
Modified by Ranga14 at 10:38 PM 4/8/2009