A 15% reduction in the supercharger pulley diameter of the MINI Cooper S increases the boost of your MINI Cooper S by more than 4 pounds, resulting in a dyno-measured gain of over 20 horsepower AT THE WHEELS. Maximum boost is achieved at lower RPM, giving more power in the mid-range of your MINI Cooper S.
Fits the following models:
NOTE: Pulley Tool included in this kit does not fit the pulley on the JCW Cooper S models. Only fits non-JCW Cooper S models.
How Small is Too Small?
Supercahrger pulleys reduced 16%, 17% or 19%, or using an oversized crank pulley, may spin the supercharger faster than our 15% pulley, but most of the additional boost cannot be used and can contrubute to engine and exhaust system damage. These smaller pulleys cause the supercharger to operate at higher RPM than it is designed to tolerate. Plus, the Roots type supercharger drastically looses efficiency at higher RPMs, generating excess heat as it tries to compress more air. In the process, it further overloads the barely adequate air-to-air intercoolers and causes the ECU to enrichen the mixture and pull back on ignition timing to preserve the engine. This results in lost power, poor fuel economy, lower reliability, the potential to 'meltdown' the catalytic converter and higher emissions.
At 15%, the ULTRIK supercharger pulley provides the most boost increase available without over-revving the supercharger at high engine RPMs. This ratio gives you added power without undue stress on the OEM supercharger or other adverse effects. Remember, if you're looking for performance increase AND reliability backed by the best Warranty in the industry, the ULTRIK 3-piece pulley upgrade system is the right choice for you and your MINI Cooper S!
And Lighter is Even Better
Compare our supercharger pulley's 7.8oz. low rotational mass design to competing all steel designs, weighing as much as 15.6oz. The ULTRIK 3-piece supercharger pulley system concentrates the weight near the treated steel center, incorporating lighter weight aluminum alloy material at the circumference, accomplishing an inertial mass 4 times lower than the 15.6oz pulleys. Ask others how much their supercharger pulley weighs. It spins very fast, so don't accept that additional mass is insignificant. Use our lightweight pulley along with our lightened crank pulley (NME5030) to really reduce rotational mass and improve acceleration.
All steel clamp design has similar thermal expansion rate as the supercharger shaft to maintain superior clamping force over entire operating temperature range.
The ULTRIK three-piece unit allows easy installation of the supercharger pulley onto the shaft without a press and enables easy removal. "Three pieces for a reason", our hydraulic press tests show the ULTRIK 3-piece pulley design superior to other tested 2 and 3 piece brand name designs. We won't mention names here, but we've tested all but the cheap knock-offs.
Locating the pulley on the shaft is easy and reliable, simply run it all the way onto the shaft until it stops. Proceed with tightening the bolts in sequence and the unique 3 piece design clamps down relentlessly on the supercharger shaft, without pulling against the stop.
The NME5041 kit, which includes the correct length belt to keep the tensioner centered in its range, is best for performance and reliability.
The kit includes high quality 3-piece self-aligning supercharger pulley (2.19" diameter), correct short length belt, and the pulley removal tool rental. See also NME5018 for Pulley Removal Tool, and NME5990 for Belt Tensioner Tool. Just installing one pulley?
We recommend the belt be inspected regularly, and replaced once a year.
Check local regulations on conformity for street use.