 | Ultra SS Lightened Aluminum Underdrive 3-Piece Pulley Set (Crank , Alt. , & P/S): Unorthodox Racing Ultra Street lightened underdrive pulleys are CNC-machined from lightweight 6061-T6 aluminum billet. Premium 6061-T6 aluminum billet ensures cons tency of material's strength balance. Tolerances are held to within .001" , numerous machining steps are used to ensure lightest possible design. In addition to fit , fin h just as important each piece representative of th . Power Gains Unorthodox Racing pulleys can provide gains of 5 to 12 HP 4 to 8 ft.-lbs. on normally aspirated engines 8 to 16 HP 8 to 18 ft.-lbs. on forced induction engines. These are average gains. Gains as high as 37 HP 45 ft.-lbs. have been realized on modified forced induction engines. These gains are obtained in two ways. First , most important , weight loss. An average of 2.7 HP gained from every pound lost off crank shaft. 85% of our gains are from weight loss. The rest of gains are from underdriving , which accounts for about 15% of total gains. Unorthodox Racing does not push underdriving for two main reasons. Our main reason to keep charging systems , air conditioning , power steering , water pumps moving fast enough for every day driving. Second , not much horsepower gained from extreme underdriving. All of our underdriving done with crank pulley , not accessory pulleys. Th done so maximum weight loss can be achieved at crank where most of horsepower gains are found. Please note: Belt(s) not included. Instructions provided with underdrive pulley will give recommended belt sizes. Belt(s) can be purchased at your local auto parts store. |
