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Unorthodox Racing Pulley Set, K24Z3 Application (2008-12 Accord I4), SU6321B

Unorthodox Racing
Product Line:
Pulley Kit
Vehicle Fitment:
Honda I-4, K-Series (K24Z3)
Unorthodox Racing Pulley Set, K24Z3 Application (2008-12 Accord I4), SU6321B



13% below retail


This pulley set for the includes an Underdrive Crank Pulley and an Alternator Pulley. Because the crank pulley has a smaller diameter than stock, shorter belt is needed to use this kit.


Light weight aluminum pulley sets are commonly used to gain power on a engine. They do not actually increase the output of the engine, but they do reduce losses introduced by adding accessories onto the engine. Amenities such as Air Conditioning and Power Steering operate off engine torque, and while they provide a benefit to a driver, there is a loss of power transferred to the transmission when these items are in use. Part of the parasitic loss comes from the standard pulleys being made from heavy steel, many times with vibration dampers installed. Billet aluminum pulleys can remove many pounds of mass from the rotating assembly, allowing faster revving of the engine. The increase in power is sometimes small, but it irrefutable. Mostly, smaller engines making lower toque benefit from lighter pulleys.

There are concerns from many customers about the impact of removing any vibration dampers from the crank. Many consumers confuse the terms "balancer" and "damper." The rubber inserts in standard Honda and Acura crankshafts do not provide any balancing benefit, as their rotating assemblies are already balanced internally. There is a damper in the stock crankshaft pulley on most applications. Removing this damper has little or no actual impact on the engine. Unlike many engines where a harmonic damper is needed to quell internal stress-inducing combustion vibration, Honda/Acura engines are typically using vibration dampers to improve NVH from accessory items cycling. In other words, any vibration increase felt by the driver after installing these pulleys is minimal (IF felt at all) and completely harmless to the car of the engine.


Here is some official copy on the manufacturer and the product line.


Ultra SS Pulley Sets Standard Belt Layout (Underdrive)

  • Real HP & torque gains across entire RPM range
  • One of the highest HP/Torque per dollar gains on the market
  • The broadest range of applications available
  • Over 8 years of use in ""real world"" applications from street to strip to rally to road course
  • Better than OEM belt fitment & alignment
  • Accessory pulleys available separately for many applications
  • CAD designed & CNC'd from 6061 Aluminum billet

Our pulley sets provide most of the power gains through weight loss (80-85%). The remaining part of the gains from these pulleys comes from underdriving of all the accessories (15-20%).However, we do not push underdriving for two main reasons. First, it is important to keep charging systems, air conditioning, power steering, and water pumps moving fast enough for every day driving. Second, not much horsepower is gained from extreme underdriving.

In most applications all of our underdriving is done with the crank pulley, not the accessory pulleys. This is done so maximum weight loss can be achieved at the crank where most of the horsepower gains are found.

Our underdrive pulley sets are available in polished finish only.

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