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MF Review: Webb Motorsports 15% Pulley

Since the introduction of the Cooper S in 2002 people have been finding new and improved ways to gain horsepower. New exhausts, upgraded air intake systems, modified ECUs and a host of other additions can help satisfy that lust for more power. Yet there’s one magic bullet in the MINI aftermarket that is head and shoulders above the rest in creating power: the super charger reduction pulley.

Warranty and Reliability

Before I get to the actual review, let me touch on what a reduction pulley does and how address a few concerns owners may have.

The principle isn’t new. Simply decrease the size of the stock supercharger pulley and you’ve got yourself a more powerful Cooper S. Dynos show gains on a 15% reduction pulley (the most popular size on the market) can over 15bhp. So with one modification your stock 170bhp Cooper S can go to 185bhp. And it gets better. The Webb Motorsports 15% Pulley tested retails for only $120 (other pulley’s msrp for about the same).

So you may be asking, where’s the rub? How is it possible that something so cheap, simple and small can add so much? The first obvious concern is warranty and reliability. The reliability question is easy when it comes to a 15%. With the JCW upgrade using a 14.6%, it’s obvious that the 15% falls well into the safe category of modifications. With MINI testing and re-testing the JCW pulley size the world-over, you can expect a pulley .4% smaller will perform the same. In fact to my knowledge (and I may be proved wrong in the comment section at some point) there hasn’t been one case of mechanical failure that was the direct result of a 15% pulley.

Now onto that pesky warranty question. MINI has left it up to each dealer and then it’s regional reps to determine if and how a pulley may have effected any mechanical failure. While I’ve never heard of this actually happening, it is technically possible for a particularly uninformed or ignorant MINI Service Advisor to use the appearance of a reduction pulley as a scape goat to deny warranty coverage on a few related internal components. It’s rare but it has happened in a few cases. To deny warranty coverage on the entire car due to a reduction pulley is just about unheard of.

It may be worth mentioning that Webb Motorsports warranties their Pulley for 2 years/24,000 miles or the remainder of your factory warranty. Some other vendors offer similar warranties.

But enough about who covers what, let’s talk performance!

Webb Motorsport Pulley Performance

Wow. That was all I could say after my first test drive. The car was eager, quick, and pulled hard all the way to redline. I could feel the difference immediately and it was impressive. In fact I was toying with simply having one word for this entire section of the review. For the longest time I couldn’t think of anything more to say than; wow.

Think about how much fun it is to row through the gears of a Cooper S from 0-60. Now add 15hp throughout the entire powerband. Or consider this; from a standing start with DSC off my Cooper S with a JCW intake, Supersprint exhaust and now the 15% Webb Motorsports reduction pulley, will put a healthy amount of rubber down in first gear, second gear, and (if I wasn’t there I wouldn’t believe it) third gear. The car feels more eager and pulls hard all the way to redline (which by the way you’ll want to watch out for a bit more with a 15%).

Or you could just say; wow.

Webb Motorsports Pulley Design

Randy Webb has been installing and designing pulleys for four years now. First it was in conjunction with Alta. However now Randy has his own design and it features a couple of unique design traits. Here’s how Randy explains his pulley design on webbmotorsports.com:

First, it is all steel. What that means is that the thermal expansion rates are the same between the pulley, the hub of the pulley, and the shaft of the supercharger. That becomes very important when the temperature deltas can vary by as much as 300F. The same thermal expansion rate means you won’t have to worry about the stability of the taper bore fitment on the shaft, or the tension between the hub and pulley.

Secondly, it is stainless steel, so the unit will not corrode over time like aluminum and mild steel do.

Third, it uses a positive stop on the inside of the pulley, so the hub is always in the right spot.

Fourth, the end of the pulley is capped, so as long as the hub is pushed all the way onto the shaft, the pulley will always align itself as it pulls the hub into itself. After having done over 800 pulley installs, I have never seen more than .02″ difference between these – the belt is always perfectly aligned.

We have several unique features on our pulley as well. We have machined a center hole to both reduce weight, and allow for easier tolerance checks. We have also worked hard at reducing the radius and therefore rotational mass.

Finally, this is a taper bore style pulley, rather than a heat and press interference type pulley. This pulley is installed at room (or shop) temperature.

As you can see in the picture at the top of the page, the Webb Pulley is almost jewel like compared too the stock piece. It’s truly a piece of art.

The Pulley Conspiracy Theory

As part of the design process for the pulley, Randy Webb did some research into this subject (w/the help of Eaton who manufacturers the MINI’s supercharger) and found that a 15% reduction is really the optimal size in regards to the powerband. So this begs the question; why didn’t BMW simply give the Cooper S a smaller pulley from the start? There are a couple of theories. The one I subscribe to goes like this: BMW didn’t want to increase an already large power gap between the Cooper and Cooper S. They also wanted to protect the low-end 3 series and the (at the time) soon to be released mid-range 1 series. By capping power on the MCS to 170bhp they are able to slot it in nicely the other cars’ offerings. They also give the JCW plenty of room at 210bhp. Helpful when you’re charging around $6,000 for the Works upgrade. Again this is all just a theory, but I know quite a few people in the industry that believe it.

Conclusion

The Webb Motorsports Pulley is an addicting, neck snapping addition to the Cooper S that simply can’t be matched by any other modification I’ve experienced. With very little to be concerned about in regards to warranty, it’s an addition that shouldn’t be overlooked when modding a Cooper S. While it doesn’t turn your car into a JCW beater, it gives the Cooper S the power that it deserved out of the factory. It’s like flipping a extra special secret switch that MINI doesn’t want you to know about. It’s also just happens to be the first product to ever recieve a perfect score in a MotoringFile review.

MotoringFile Rating: 5 (out of five)

Where to Buy: The Webb Motorsport Pulley retails for $120 and can be purchased from Webb Motorsports. Several other MotoringFile sponsors carry a similar pulley as well. Promini, Helix, Outmotoring and MyMini all carry 15% pullies and M7 carries their own 16% design.

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Written By: Gabe

  • tsukiji

    Dead solid perfect

  • lTZMTOR

    My dealer, an IGNORANT BUNCH, not my SA, he’s kool, Asseal here in SoCal has already warned me…Don’t Do It! Don’t track it! Don’t pulley it! Nothing…. that they don’t approve 1st.

    I did ask them about a Dinan pulley, I think they make one, since they do authorize that companies parts… not a word yet.

    So I don’t have the time or enough MONEY to fight BMW.

    Thanks for another fine review… maybe some day when my 100,000 warranty expires I will do it.

  • bwanayak

    What effect does the pulley upgrade have on fuel economy?

  • http://www.iniw.net Randy K.

    The first 5 out of 5 review! – Way to go Randy!

  • http://www.motoringfile.com/ Gabe

    What effect does the pulley upgrade have on fuel economy?

    None that I can tell other than I mash the go pedal a lot more since the power is addicting.

  • JD7

    Are their any necessary prerequisites when considering a pulley? For example, should one already have a CAI or exhaust? I noticed that was the order of your mods and I have considered the same for myself.

  • Lee L

    It is definitely a huge improvement and you can’t beat the cost. It does make the car feel like it should have felt from teh factory.

    As far as looks, when I installed my Alta plulley 2 years ago, I said the same thign, it looekd like a work of art. I almost felt bad putting it on the car and leaving my stock pulley on my desk, but only for a second. ;)

  • http://www.motoringfile.com/ Gabe

    Are their any necessary prerequisites when considering a pulley? For example, should one already have a CAI or exhaust?.

    Good question and one that is easily answered: no.

  • FH

    I just got the 15% pulley installed last weekend, and got the chance to test it out on a deserted back road. WOW! pretty much sums it up, and comparing my computerized fuel economy on the return trip, I didn’t see any difference yet; I am on my first tank of gas still so we’re talking about a very small sample size.

  • http://TwistedMotoring.org am0eba

    I have a 2005 MCS Cabrio, and based on info about lower, better gearing in the Getrag 6-spd vs. earlier models, I wasn’t expecting a huge change from a 15% reduction pulley. Based on that thinking, I was planning to wait and get other mods installed first. When I found out that Randy Webb’s last-ever LA area Pulley Party was taking place, I decided to get mine installed by the “experts” then.

    I am AMAZED by the change in performance – Standing starts are much smoother now, and less clutch finesse is required, regardless of whether the start is “spirited” in nature or not. Third gear on the Getrag 6-spd is useful at almost any legal street speed, with gobs of torque available for passing. And the sound… I didn’t expect a big change, but the audible feedback, even without an intake or exhaust mod, is substantially different: not louder, but much more “eager” and “zoomy”. To address the gas mileage question, Gabe is right on: there’s probably very little difference at a particular engine speed/gear selection combo, since the reduction pulley is merely adding more air to the mix, but the improved torque, horsepower, and sound characteristics tend to alter one’s driving style to the point where fuel consumption per mile is affected.

    I wasn’t in a hurry to get a SC reduction pulley, but I’m SO glad I did!

    Dave

  • Aqualung
    Now onto that pesky warranty question. MINI has left it up to each dealer and then its (ed) regional reps to determine if and how a pulley may have effected any mechanical failure. While I’ve never heard of this actually happening, it is technically possible for a particularly uninformed or ignorant MINI Service Advisor to use the appearance of a reduction pulley as a scape goat to deny warranty coverage on a few related internal components.

    I understand that Randy is no longer in the pulley party business….will MINI dealers do this install despite the above, i.e. the ones that would do this are obviously favorably predisposed towards owner mods? Or where does one turn to for it? Do-it-yourselfers? Trusted mechanic? How long should an install take, in order to estimate a cost?

  • http://Hrmini.com AlvaroSpatchez

    I’m #726 for WMS 15% and I love it. The sound is undescribable. Makes the MINI sound more like and F1 car than an English 4cyl. No reliablity issues for me and fuel economy has been maintained. Plus if Randy does the pulley for you. the drive afterwards is worth it all! I can’t say enough about Randy Webb, he’s the best.

  • Jac

    Gabe

    thank you for the great write up. Still deciding on a size – hard to pick the reliable favorite 15% when i know there is just a little more out there…. :)

    quick question, what size belt did you use? Stock? JCW?

    thanks!

  • http://www.motoringfile.com/ Gabe

    quick question, what size belt did you use? Stock? JCW?

    Stock.

  • Nathaniel Salzman

    Pulleys and intakes and pipes, oh my!

    Awesome review Gabe! I’ve been waiting for this on for weeks. I was expecting a 5:5 rating and from your description it’s no surprise. Congrats man.

    Any thoughts of a rear sway bar? JCW suspension?

    And I sure hope everybody grasps just how much the aftermarket developers and especially Randy do for the MINI community. I only really know about WMS methods, but the scientific approach they’ve taken in doing their development gives me a lot of confidence in their equipment. And I think the mule on the track is proof plenty of their performance.

    So “hazaa!” for all the fine folks bent on making our MINIs faster!

  • Chad in VA

    Sounds to me like I’ll be joining the pulley club soon, and with a WMS pulley at that. A question, though – has anyone put a pulley on an MCSa and noticed the same type of “wow” difference?

  • Beavers

    I asked my SA for an estimate on the pulley install. I had already picked up an Alta online ($107!) a while back, and was tired of waiting for my mechanic to find a free weekend for me.

    The estimate came back at $400. I said no thanks, and put it on last weekend. Installation went smoothly, with the exception of not having the proper pulley removal tool (BIG mistake.) I did have a very experienced mechanic with me, though, and a wicked set of tools : ^ )

    Beavers (Daddy Duper)

  • Jac

    thank you! enjoy!

  • http://mini.mdsbrain.com mdsbrain

    Gabe what a write up! I will use your review as a good means to help show why the pulley is the upgrade to do.

    Oh man…the first 5 OUT OF 5 review. WOW!

  • Garth Erdrich

    I did the pulley, exhaust and intake in one fell swoop when I had my ’02 MCS. HUGE change in the car/charatristics. I too used the stock belt but as I had 20k on my car already, I did replace the belt just to be safe (and since it was already off the car;-). I am awaiting delivery of my ’06 MCS and will be doing this very shortly after break-in.

    Gabe, I could not agree more with your comments; an absolute hands down, safe, must do mod for any MCS that is driven as the car was designed to be driven.

  • mark

    anybody do the 15% install on a MCSa? be curious as to the differences

  • ezra360

    Allright! I’m sold. I second Aqualung’s question- if Randy is no longer doing installs, who’s taking the reins? From other info I’ve read the install quality can vary from mechanic to mechanic. Any reccomendations?

  • david

    OK, dumb question: how complicated is this to do? There doesn’t appear to be much about how to actually do this scattered about on the web…

  • http://www.motoringphotography.com Dave
    how complicated is this to do? There doesn’t appear to be much about how to actually do this scattered about on the web…

    Randy Webb’s Supercharger Pulley How-To

  • http://www.alldigitalnyc.com drew

    great write up gabe! of course you’re preaching to the choir on this one… ; )

    chad – as for the 15% pulley on the mcsa – check out my motoringfile review at http://motoringfile.com/2006/04/03/mf-review-mcsa-w15-pulley/

    the short answer is…wow.

  • tsukiji

    5 outa 5 is absolutely spot on.

  • Chad in VA

    Drew, thanks for the link. I remember reading that article when you first posted it, but my knowledge level and enthusiasm for modding have increased a whole lot since then. Now I just need to find a reputable place for the install.

  • Brian

    Dave – Just called Pete at MyMini. Im gonna get the pully installed up there in a few weeks.. looks like a lot of work though. -Brian

  • http://dcmini.blogspot.com/ DanC

    Wow, indeed.

  • Jason K

    Hey Gabe,

    Great review, but I think you made a minor technical error:

    Think about how much fun it is to row through the gears of a Cooper S from 0-60. Now add 15hp throughout the entire powerband.

    15 HP is roughly 9% of 170 HP, and since supercharger speed increases linearly with engine RPM, it’s likely that a 15% pulley does not increase power by 15 HP through out the rev range but rather by 9 percent. Obviously, a dyno curve is the ultimate arbiter here, but “15 HP throughout the powerband” is likely a bit inaccurate.

    Like I said, this is minor and everything else in the review is fabulous. This is great information.

    Jason

  • Edge

    Great review Gabe, well written… my only gripe is one of my pet peeves… your use of the word “addicting” instead of the more proper (and much better sounding, IMO) word “addictive”. :P

    Thus concludes your wannabe-English-teacher lesson for the day. (grin)

  • http://lawrenceotoole.com/mini/mini.html lawrence

    Nice writeup, Gabe.

    I finally got on down to Helix myself (a mere five blocks away!) last month and cashed my Christmas gift certificate in for a 17% pulley.

    Neck snap is exactly the right term to describe the difference. It’s not a total transformation, but rather an upgrade just where the car seems to need it. When the power comes on, it just keeps coming, pulling and pulling in every gear until redline. A nice solid kick in the boot. No need to downshift to pass. Like am0eba said, launching is much smoother, and the sound is great – a higher pitched and slightly sharper whine from the charger. It really puts a smile on the face!

  • JD7
    Edge Jun 28th, 2006 Link Great review Gabe, well written… my only gripe is one of my pet peeves… your use of the word “addicting” instead of the more proper (and much better sounding, IMO) word “addictive”. :P Thus concludes your wannabe-English-teacher lesson for the day. (grin)

    Along those same lines (sort of), Gabe, this seems to be your first review not using one of the following phrases;

    “that being said,…” “having said that,…”

    I guess I have an eye for detail. “Having said that”, I am constantly reminded what a poor reviewer I would make each time I read one on MotoringFile. As usual, this is a very informative and well written piece of MINI information.

  • 05DSMCS

    I ain’t worried about your grammar, Gabe. Thanks for the write up, now I have to figure out how to scoot out to Denver for the weekend and get me some of this.

  • http://www.motoringphotography.com Dave
    Thanks for the write up, now I have to figure out how to scoot out to Denver for the weekend and get me some of this.

    Here’s one way to do it

  • Nick

    The DOWN side of a 15% reduction Pulley–if you have a mechanic screw it up. Sad story. Had an experienced (30+ yr mechanic due the install) Worked on British cars for yrs. Owns 2 MINIs. He broke 2 pulley pullers and had to torch off/chip off the oem pulley. Car in his shop several days. Several months go by, I notice the belt is getting frayed. Had my 10,000 mile servce. Paid $124 to replace the belt at my dealers. Several days later I am hearing not good sounds emmitting from the SC pulley area. Called MINI–car trucked to dealer (Jax,FL) The verdict: bearings/and whatever shot on SC. New SC–$1400/labor $700. 1 way car rental $100. Aggravation. YES. SOOOO, I am back to stock SC. Now I wish I had opted for the JCW. Next one for sure. Thanks for letting me share. As the old Sergeant on Hill Sreet Blues use to say “Be careful out there”.

    • Kenneth

      Dear Nick,

      I’m from Malaysia and I drive a MCS. Your misfortune is exactly what I’m going through. I had installed an Alta 15% pulley with the proper belt and after driving about 200kilometers my Belt had frayed basically 1/3 of the belt had shreded 2 weeks ago. However I did manage to drive my MCS back slowly to the repair shop. I than had the belt replaced and this time the belt had literally shreded leaving the belt holding by the whisker after 4 days of using. This time to prevent the belt snapping I had to get the Mini towed.

      On reading your comment I recall that the mechanic who had installed the Alta in December 2011 had broke the pulley puller and had to torch as well as saw off the OEM pulley thus damaging the shaft as well as there were groove marks on it. I believe all the excersive pulling and knocking off the OEM pulley had in all probability damaged the supercharger shaft maybe by pulling the  shaft out by 2mm.

      The reason I say by 2mm is because when my regular mechanic replaced the first belt he noticed that the Alta pulley was about 2mm out from the other pulley thus making the alignment off. This is what caused the belt to fray and eventually shred. However it was strange as my Mini did not experience any loss in power or sounds emmitting from the SC pulley area. Perhaps mine is at an early stage.

      Currently my car is in the shop as my mechanic is now distmantling my supercharger to check and compare with a new supercharger and ascertain if the shaft has moved by 2mm.

      Advice to all you Mini MCS please go to the more experience mechanics. A very expensive and annoying experience. If anyone else had any similar experience do let me know as I’m still not very certain if it is my supercharger that is causing this problem. 

      Kenneth  

       

  • fdavid

    I have an appointment with Eric at Helix13 wohoo!! Thanks for the write up Gabe, good job!

  • badburro

    Would someone please discuss the disadvantages to going with a smaller (17%, 19%, etc.) pulley? Thanks.

  • Brian
    badburro Jun 28th, 2006 Link Would someone please discuss the disadvantages to going with a smaller (17%, 19%, etc.) pulley? Thanks.

    Those pulley sizes start making everything move too fast (in relation to stock or 15% pulley) and although they provide more boost, most people don’t recommend them for street use since you can mess up engine/supercharger parts sooner.

  • jdmarino

    Is there a reason to get the WebbMS pulley over the JCW one? They are about the same size. Is one better engineered than another?

    I’m not handy under the hood, still under warranty, and thinking, if the price is right, of having the dealer install a JCW pulley to get that WOW. Most likely they will want to rob me, so I won’t do it. And I don’t have another mechanic I trust to do it.

  • http://www.motoringphotography.com Dave
    Is there a reason to get the WebbMS pulley over the JCW one? They are about the same size. Is one better engineered than another?

    The WMS pulley costs $120 + install. The JCW one is only available with the full JCW kit.

  • Nathaniel Salzman

    It’s curious that in describing the JCW engine kit, they show a completely new supercharger – not simply a smaller pulley on the existing compressor. I’m assuming that if you got the kit installed at the dealer that they’d swap the whole unit, but I may be wrong. My question is whether or not it is actually a different supercharger than stock. Is it just the same ol’ Eaton with a reduction pulley pre-installed and they just swap the whole unit, or has it got beefier bearings or something? I wonder.

  • MINIAC

    There used to be a different coating on the supercharger rotors. Now the only difference between the supercharger in the JCW Kit and the stock unit is the size of the pulley.

  • http://www.plusminus.com.au Russell

    So what are us poor bastards with Coopers meant to do then eh? :(

  • http://www.motoringfile.com/ Gabe

    Would someone please discuss the disadvantages to going with a smaller (17%, 19%, etc.) pulley? Thanks.

    Big disadvantage is wear on components. I’ve seen first hand water pumps fail or track cars with 19% pullies. Not a pretty site.

  • Joel

    Excuse my stupidity, what size pulley is on the JCW Kit?

  • j

    a couple of things. 1st- thanks for the review. i never really understood how it works and what it does for the supercharger. and i never had the balls to ask cuz i thought i wwould get ripped apart.

    2nd. To gabe or anyone else, what are some of the other available sizes and what other increases in power can u see from them

    and 3rd- gabe, i agree with ur theory. thats exactly how porsche KINDA shot themselves in the foot with the caymen. they wanted to make a car to slot right in between the boxter and 911 but they got the equation so right that people now have to ask ” why should i spend an extra 25-30k just to go a hair faster?”

    but now with mini surpassing original expectations can we see a smaller pulley in the next JCW (if plans for it have not already been released)?

  • MINIAC
    I’ve seen first hand water pumps fail on track cars with 19% pullies.

    19% reduction is NOT recommended for track use.

    what size pulley is on the JCW Kit?

    Somewhere between 14% and 15% reduction.

  • badburro

    MINIAC -

    Are you saying that the thousands of dollar I would be paying for a JCW supercharger is just for a reduced pulley size and not a new and improved supercharger? What about the cylinder head???

  • JD7
    j Jun 28th, 2006 Link a couple of things. 1st- thanks for the review. i never really understood how it works and what it does for the supercharger. and i never had the balls to ask cuz i thought i wwould get ripped apart. 2nd. To gabe or anyone else, what are some of the other available sizes and what other increases in power can u see from them

    15% Webb, Alta, and others 16% M7 17% Alta, others 19% Alta, others

    I can’t give you the #s on power increase, but I am sure someone on NAM or MINI2 already has.


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