BMW Underdrive Power Pulleys for BMW Z4 M Roadster S54 (2003-2008)

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Reduce parasitic loss of power on your BMW's engine by safely under driving the belt driven auxiliary systems. Reducing this drag on your engine results in MORE HORSEPOWER AND TORQUE to the wheels of your BMW. Our BMW underdrive power pulley kits are specifically designed for each BMW application to make the best power while maintaining stock driveability and reliability, eliminating potential downsides. Others may advertise "their" pulleys boasting more power, but we concluded that for street and track driven BMWs, ours are the best size and design to ensure both your engine and it's belt-driven systems (alternator, water pump, power steering etc) are well within safe operation. We run these under drive pulleys on our own BMWs, so we would not want them any other way.
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Turner Motorsport Power Pulley Upgrade Kit - Z4 M Roadster & Coupe
Turner Motorsport Power Pulley Upgrade Kit - Z4 M Roadster & Coup...
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Turner Motorsport - Corporate Logo
T#:3465
Part#: PPK-MZ4
Ships on Aug 26, 2025
Sale - Save 30% $ 340.99
$ 238.69 USD
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Sale - Save 30% $ 340.99
$ 238.69 USD
Free Shipping
Add to Wish List
Underdrive Power Pulleys work to 'free up' horsepower. Any accessory that spins from the main drive belt is using up power. That's power that could otherwise be used to move the car. By giving some of that power back to the engine, you can make the car faster! It's like FREE HORSEPOWER !

Underdrive pulleys for your BMW will slow down engine-mounted accessories - the water pump, power steering pump, and alternator*. These systems contribute to 'parasitic losses' - power lost from what the engine could produce if it did not have these systems. Since less energy is used to move them, that power is transferred back to the engine and used to propel the car. Our pulleys give a 10-20% reduction in rotation, releasing up to 11hp on most BMW six-cylinder engines. There's also a small but noticeable improvement in throttle response too! We have done extensive testing and development work, both on and off the track, to ensure that the accessory systems function as they should. On our Racing pulley kits we actually underdrive certain components more so we feel our Street pulleys are an ideal compromise between power/torque gains, reliability, and system performance. Our pulley kits have been on the market for over ten years, and used in all of our own cars, with zero component failures related to their use.

Our pulleys are made from T-6061 aluminum and finished in a durable black hard anodize that is very resistant to wear, chemical exposure, and heat. We designed our pulleys to look similar to the factory parts but also to be stronger and, in most cases, slightly lighter too. For example, With our hardcoat aluminum you will never have to worry about a serious failure of a stock plastic pulley. A 'stealth' approach to aesthetics was our goal and we let the results speak for the pulley design. Installation is straight forward and easy with simple hand tools. Removal of the fan is required for access to the front of the engine. Total install time for a 3-piece pulley set should be around 1.5 hours. A new longer belt is included and we also recommend replacing the separate A/C belt, belt tensioners, and the guide and deflection pulleys at the same time.



Additional Info
Clickhere for example dyno graph

Click here for installation instructions.

Turner Pulley Kit contents:
  • Turner water pump pulley
  • Turner power steering pump pulley
  • new extended length belt
  • instructions

    This underdrive pulley kit fits the following BMW:
    2006-2008 MZ4 Z4 M Coupe / Z4 M Roadster
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    S54 VAC Harmonic SuperDamper By ATI - Standard Size Crank Pulley
    S54 VAC Harmonic SuperDamper By ATI - Standard Size Crank Pulley ...
    ATI Performance Products - Corporate Logo
    T#:639878
    Part#: VAC-HPCDK-S54-ST
    In Stock
    $ 1,049.99 USD
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    $ 1,049.99 USD
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    If you are breaking crankshafts and oil pumps, the cause may be a mystery to you as it has been to many of our customers. We know that controlling the harmonic resonance of the BMW 6 is highly important as RPMs rise, but the ideal configuration of the inline-6 motor makes even experienced engine builders overlook some fundamental principals of engine harmonics that can be destructive. ATI Performance Products has partnered with VAC Motorsports to develop new dampers for BMW 2.5L, 2.8L, 3.0L and 3.2L straight-6 engines found in the E36 and E46 M3, E9X and E6X, as well as newer Z3s and Z4s. These dampers eliminate crankshaft harmonic vibration, which allows the engine to produce more horsepower and torque, while also reducing internal engine wear at the same time. Broken oil pumps and timing chains will be a thing of the past! When used with a VAC accessory pulley, these dampers are a direct replacement over the OEM balancer. They have a 7” outer diameter and include OEM style timing alignment tabs. BMW enthusiasts should know that all ATI Super Dampers exceed SFI 18.1 Safety Certification and are approved for competition. The advantages of the ATI SuperDamper include eliminating vibration issues with inline 6 engines equipped with lightweight clutch and flywheel assemblies, reduced bearing, engine accessories, oil pump wear, and compatibility with underdrive pulleys. Made in the USA.
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    Rogue Engineering Power Pulley Set - S54 - E46 M3, Z3/Z4 M
    Rogue Engineering Power Pulley Set - S54 - E46 M3, Z3/Z4 M
    Rogue Engineering - Corporate Logo
    T#:553971
    Part#: PP.S54
    Ships in 9 Business Days
    $ 259.00 USD
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    $ 259.00 USD
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    Rogue Engineering has developed a power pulley kit that reduces the drag on specific pulleys while allowing others to remain at their same efficiency. This allows for perfect operation in daily driven vehicles without a hiccup or stutter. However, when the demand for power is requested, the power pulley kit allows for the freed power to become apparent.  The term "power" pulley is a bit of a misnomer. Underdrive pulleys actually free up power by reducing the drag caused by the accessories.  These pulleys are based off a calculated percentage from factory dimensions, so that particular component speeds are safely reduced without affecting their true purpose.

    Rogue Engineering Power Pullies are CNC machined from 6061-T6, heat treated aluminum and specially coated with a MIL-A-8625 Type III hard coat anodize finish. This kind of anodizing is not to be confused with a Type II cosmetic anodize finish (typical colors such as red, blue, silver, green, etc.). The hard coat anodize finish actually builds a small surface layer on top of the aluminum, preventing wear.

    This part fits the following BMW engines:
    S54

    This part fits the following chassis:
    E46, Z3, Z4

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