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Part number: CS1311B
Product Details
Unorthodox Racing CS1311B Pulleys - Crank Pulley
Products specifications
Weight 7oz
Crank Pulley & Belts
Stock Diameter
73% Lighter Than Stock

Unorthodox Racing Crank Pulleys are available in a number of configurations.

Standard Belt Layout (Stock Diameter)

Many of our customers have asked for crank pulleys that do not underdrive their alternators, power steering pumps, superchargers and water pumps. Because of these requests we developed our stock diameter crank pulleys. Many customers want the performance benefits of weight reduction without any sacrifices, especially audio enthusiasts as some audio competitions require voltage to remain at a specific level. With our stock diameter crank pulleys the alternator and other accessories spin at stock speeds with NO underdrive. This is also important for stock or aftermarket supercharger systems. These systems are either driven off the alternator, air conditioning or power steering sections of the crank pulley and now you can use our stock diameter crank pulleys with these supercharger systems and have the same boost you had with the factory crank level with the use of the factory diameter crank pulley.

100% of the power gains from the stock diameter pulleys comes only from weight reduction versus the factory crank pulley. The reduced weight allows for more power transfer to the drive wheels. Any of our accessory pulleys that are listed individually can be used in any combination with our stock diameter crank pulley or purchased as a set. The stock diameter crank pulleys are available in polished finish only.

Standard Belt Layout (Underdrive)

Our most popular crank pulleys, the ones everyone is familiar with. This version of our crank pulleys increases performance because they underdrive all the accessories (15-20% more power), unlike accessory only kits out there that do not include the crank pulley. This means one you air conditioning is on our crank pulleys give you more power back to the wheels by not letting the air conditioning compressor rob as much power.

However, we do not push the amount or percentage of underdrive too far 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. We always keep our underdrive percentage under 20% which is what allows us to maintain factory specified outputs for all your accessories. Our testing has found for most vehicle models you can upgrade your stereo to a system of up to 600 watts (RMS) and not have any charging problems.

For most applications all of the underdriving is done at 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 realized. The Ultra Series underdrive crank pulleys are available in polished aluminum finish.

Single Belt Conversion (Underdrive)
Single-belt crank pulley conversions go even further to provide you with the highest possible power gains. They are also a must in many of the Acura/Honda engine swaps where the stock pulley will not fit because of clearance issues. The single belt design only drives the alternator . This makes for an extremely light piece that will provide you with excellent power gains. Single-belt crank pulleys are also perfectly streetable and can be used in many Acura/Honda applications where the A/C and P/S are being removed for street or track use. Our single-belt conversion crank pulleys are only available in polished aluminum finish.


  • 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 seperately for many applications
  • CAD designed & CNCd from 6061 Aluminum billet
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