| 
> Shop by Makers
> Subaru
Performance Tuning >
Subaru GD Impreza WRX, STi, 2.5RS, 2.5TS upgrade index >
Subaru
04-up Impreza WRX / STi UR Ultra SS pulley set
Unorthodox Racing Ultra
Street Pulley Sets are CNC-machined from lightweight 6061-T6 aluminum
billet. Premium 6061-T6 aluminum billet ensures the consistency of the
material's strength and balance. Tolerances for each crank and accessory
pulley are held to within .001". In addition to the numerous machining
steps taken to ensure the crank pulley is the lightest possible design,
each accessory pulley is also lighter than the factory piece it replaces
and includes lightening holes where possible.
Unorthodox Racing pulley sets on average can provide gains 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 vehicles that are modified.
Unorthodox Racing Ultra Street Pulley gains are obtained in two ways.
First, and most important, is the weight loss. There is an average of
2.7 HP 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 underdriving, which accounts for about
15% of the total gains. We do not push underdriving for two main reasons.
Our 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.
|
