Unorthodox Racing Ultra Street Set (Ultra SS) pulleys. Made of lightweight Premium 6061-T6 billet aluminum to ensure consistency of the material's strength and balance. CNC machined to .001". This is the complete Street pulley set that consist of the Ultra S crank pulley as well as all of the Ultra A accessory pulleys for each application. An average of 8 to 15 HP and 6 to 10 lbs.-ft. on normally aspirated engines and 10 to 18 HP and 10 to 20 lbs.-ft. on forced induction engines. Higher gains can be realized on modified engines. 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. With the lighter accessory pulleys, as much as 15% to 30% more power can be found. 85% of our gains are from weight loss. The rest of the gains are from under driving, which accounts for about 15% of the total gains. Under driving is not pushed for two main 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 under driving. In most applications all of the under driving is done with the crank pulley, not the accessory pulleys. This is done so maximize weight loss can be achieved at the crank where most of the horsepower gains are found.
** Includes Genuine Nissan Belts **