Originally Posted by Unothodox Racing

Weight loss is the most critical factor in HP production, each lb. of mass taken off the crank/eccentric shaft is worth approximately 2.7 HP and the figure increases with forced induction, nitrous, VTEC and increased RPM's. Only 15-20% of the gains seen from our pulleys comes from the underdriving. We achieve the maximum gain for each application/model by the singular use or combination of reduced diameter ("underdriving") and weight loss versus the OEM crank pulley/s. This principle allows us to maximize the HP gain without causing any adverse effects in the general function of the vehicle.

The diameter of each of our crank pulleys is reduced specifically (from 20-30%) to the vehicles accessory needs. In other words we maintain all accessory minimums: air conditioning efficiency, power steering feel, and voltage (minimum allowable voltage 12v) even at idle with everything electrical on in the car. There are no adverse effects from the use of our pulleys whether Ultra S, Ultra R, or Ultra SS pulley sets are used. Bolt them on and forget about them, then just follow your vehicles normal maintenance schedule.

Originally Posted by Unorthodox Racing

The factory pulleys on today's late model cars (from 1986 to Present and sometimes even earlier depending on the vehicle) serve two functions. First and most importantly they are designed to reduce or eliminate the audible noises herd in the cabin of the car that the accessories (alternator, air conditioning, power steering, and air pump) make when the engine is running. This fact exhibits the factory fanaticism about making the car quiet for the occupants (i.e. the use of resonators in the intake to quiet intake noise, all aftermarket intakes eliminate these resonators). It has nothing to do with engine function or longevity.

The second function of late model crank pulleys is torsional damping. Torsional damping is necessary due to the excessive diameter and weight of the factory crank pulleys. The design of our underdrive crank pulleys eliminates the need for any torsional damping for two reasons. One, the diameter of our crank pulleys is smaller than the original designs, in almost all cases smaller even than the rubber torsional ring, therefore effectively reducing the force the accessories have on the crankshaft. Second and most importantly is that our pulleys are significantly lighter than their OEM counterparts (anywhere from 3 to 11 lbs.). This weight loss dramatically reduces the stress exerted upon the rotating assembly by the excessively heavy factory crank pulley.

Our pulleys are so well balanced that when owners call us about how happy they are with the product they always mention their motor feeling smoother. Lastly is the misconception that the crank pulleys on these vehicles are harmonic dampers. A harmonic damper is a unit bolted to the crankshaft snout that is completely separate from the belt drive system. An engine that uses a harmonic damper has the accessory drive crank pulley bolted to it, they are separate pieces that are attached to each other. Balance shafts, which are used by several manufacturers, are specifically designed to eliminate harmonic vibrations. None of the vehicles we manufacture pulleys for have harmonic dampers in the traditional sense.

Owners who have engines that use balance shafts must understand that if they eliminate their balance shafts their engines must be balanced to 0 grams if they expect to have no long-term engine problems with or without the use of our crank pulleys. Our pulleys are made with 6061-T6 aluminum billet which is a very consistent material and the CNC machining process ensures that all our pulleys are perfectly true. This balance shaft elimination is rare and only happens on a few models that are modified for racing only (Eclipse/Talon/Laser/Galant VR4/Conquest TSI/Starion just to name a few).