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Unorthodox Racing

Unorthodox Racing

Ultra S Lightened Underdrive Crank Pulleys

Unorthodox Racing Ultra S Lightened Underdrive Crank Pulley

(Main component of Ultra SS kits)

  • Lightweight 6061-T6 billet aluminum
  • CNC machined to .001"
  • Real HP & torque gains across entire RPM range
  • Over 6 years of use in "real world" applications from street to road course to rally to dragstrip...
  • Better than OEM belt fitment & alignment
  • The broadest range of applications available
  • High quality polished & anodized finishes

Unorthodox Racing Ultra Street lightened underdrive crank pulleys are CNC-machined from light weight 6061-T6 aluminum billet. Premium U.S. made 6061-T6 aluminum billet en sures the consistency of the material's strength and balance. Tolerances are held to within .001", and numerous machining steps are used to ensure the lightest possible design.

In addition to fit, finish is just as important and each piece is representative of this. Every pulley is inspected multiple times from machining to anodizing to stocking and finally at shipping time. If at any point a pulley does not pass inspection it is pulled from production.

Unorthodox Racing lightened underdrive crank pulleys on average can provide gains of 5 to 12 HP and 4 to 8 lbs.-ft. on normally aspirated engines and 8 to 16 HP and 8 to 18 lbs.-ft. on forced induction engines. Higher gains are possible. For example, a Nissan 300ZX twin-turbo saw gains as high as 37 HP and 45 lbs.- ft. on the dyno just by replacing the stock crank pulley with our Ultra S lightened underdrive crank pulley.

Power gains are obtained in two ways. First, and most important, is the weight loss. An average of 2.7 HP is gained from every pound lost off the crank shaft. 85% of our gains are from weight loss.

The rest of the gains are from underdriving, which accounts for about 15% of the total gains. We do not push underdriving beyond 20% for two important reasons. The main reason is 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 the 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.

Unorthodox Racing Ultra Street crank pulleys cover a vast, unparalleled array of applications, including those with timing rings. Depending on the application, Unorthodox Racing will either supply a new timing ring or you will bolt the stock timing ring to the pulley. All timing rings are laser cut to exact specifi cations. If not cut properly, your vehicle may not run correctly, return error codes, or not run at all. You can always count on the quality of our pulleys and timing rings to keep your vehicle running for years to come.

Many Unorthodox Racing Ultra Street pulley applications are available in Ultra Street Sets which (in most cases) include all the accessory pulleys except for the A/C compressor. You can always purchase an Ultra Street crank pulley first, and then upgrade to an Ultra SS kit with the purchase of the Unorthodox Racing Ultra Accessory pulleys. Ultra Street lightened underdrive crank pulleys are available in natural polished aluminum as well as black, red, and blue anodizing. Please note that on some models anodizing is a special order and may require additional time to ship.