Unorthodox Racing Ultra Street (Ultra S) lightened under drive crank pulley. Made of lightweight Premium U.S. made 6061-T6 billet aluminum to ensure consistency of the material's strength and balance. 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. An average 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 buy replacing the stock crank pulley with the Ultra S lighted under drive 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 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 **
The HI OD water pump pulley is recommended to be purchased at the same time. The HI pulley can be found HERE