1997 - 2009 Chevrolet Corvette Pulley ASP941020 25% UD Harmonic Crank Pulley (LS1/LS2/LS3 )

Crank pulleys, attached to the outside of the crankshaft, are the source of power for a car’s accessories. The alternator, power steering, water pump, and air conditioner are all belt driven units, attached to the crank pulley, that use horsepower from an engine to provide their own services. Underdrive pulley systems increase an engine’s horsepower by reducing the power required to drive the external engine accessories. By replacing factory pulleys with carefully resized units, the accessories are slowed enough so that their performance does not suffer, but just enough so that more horsepower is sent to the wheels and put to the ground. Where horsepower should be.

Normally, underdrive pulleys like the units found at NonStopTuning will increase engine output by 10 to 12 horsepower, with even better power levels yielded from turbo models than seen in naturally aspirated engines. This increase results in quarter-mile time and road course lap improvements, easily making this modification one of the best “bang for your buck” modifications for any car.

​All pulleys are manufactured from Billet Steel or Aluminum, exceeding factory quality.