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.
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.
Written By: Gabe
Sort by MINI model
- Video: MINI Safety Campaign Literally Explodes in Women’s Faces
- The Classic Mini says “Happy Birthday” to the Porsche 911
- White Roof Radio #470
- MINI USA Sales Down -3.4% for May 2013
- MINI Extending ALL4 to Cooper Countryman and Paceman Models in Europe
- R50/R53 MINI Power Steering Warranty Extension
- 900hp MINI to Race at Pike’s Peak
- This is the 2014 F56 MINI’s Shift Knob
- Is MINI Preparing a New Campaign for the Infamous Chain Tensioner?
- Woofcast #470 – Live
- BMW M3: Evolution Over the Years
- BMW 228i Prototype Crash Causes Autobahn Closure
- Breaking: BMW’s Carbon Fiber Suspension Revealed
- 2013 ConnectedDrive Updated for the US Market
- BMWNA Launches the 3 Series Diesel Configurator
- BF Preview: The BMW M Track App for iOS
- The Ultimate Gallery: The BMW M6 Gran Coupe at the Circuit of the Americas
- Video: BMW HP4 vs. BMW R 1200 GS
- BMW Updates Connected Drive with SIM Card Slots, App Store & Improved Speech Recongnition
- Spied! 2014 BMW 4 Series Loses More Swirls
- An Ingenious DIY Scooter Trailer
- Video: The New Piaggio Fly 150 3V
- Video: Vespa World Days 2013
- Opinion: Will Electric Scooters Ever be Viable in the USA?
- Electric Bikes to Grow 10X by 2018 in North America
- Video: The Vespa 946 is “Hand Made”
- Video: Rome by Scooter
- Vespa Expands its Presence in Eastern India
- A New, Responsive Vespa.com
- Recapping the Chicago Genuine “Family Reunion” Ride
MINI Model Cheat Sheet
Advertise with MotoringFile
MotoringFile Buyers GuidesR50 ('02-'06 MC) Buyers Guide
R53 ('02-'06 MCS) Buyers Guide
'12 JCW Coupe
'11 Fiat 500 Sport
'11 Tesla Roaster 2.5 '11 Countryman Comparo
'11 Cooper S Hatch
'11 Countryman MCS (FWD)
'11 Countryman MC (auto)
'10 Mayfair MCS (auto)
'11 Countryman MCS (ALL4)
'10 MINI E
'10 Tesla Roadster Sport
'09 Cooper S Convertible
'09 JCW Hatch
'09 JCW Clubman
JCW Stage I vs JCW Stage II
'08 Clubman S (Auto)
1st Drive: '08 MINI Clubman
'08 Smart Fourtwo
Comparison: '08 BMW 135i
'06 R53 MCS vs '07 R56 MCS
'07 R56 JCW (Stage 1)
'07 MINI Cooper S Long Term
'07 BMW Z4 M Coupe
'07 MINI Cooper & Cooper S
Audio: '07 MC/MCS at the Track
'06 JCW GP Long term
Reader Review: JCW GP
'06 JCW Cooper S Long Term
Comparison: '06 Lotus Elise
Comparison: '06 Mazda MX5
Comparison: '06 UK Focus ST
Comparison: '06 Civic Si
Comparison: '04 TVR T350
Comparison: '06 Nissan 350z
Comparison: '06 VW GTI w/DSG
Podcast: Cooper S Auto
Podcast: BMW 325i
Podcast: JCW MC Soundkit
'04 JCW MINI Cooper Tuning Kit
'05 MCS: One Month Review
'05 MCS Auto
'05 JCW S 1st Drive
'05 MINI Cooper
'05 MCS Conv. Long Term
'05 MINI Cooper S
'05 MCS Cabrio 1st Drive
'04 JCW MCS First Drive
'04 MC w/JCW Tuning Kit
BMW M3 SMG Vs. MCS
'04 MINI Cooper CVT
'02 MCS 3 year Review
Autocrossing the MINI Range