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 8 to 15 horsepower, with even better power levels yielded
from turbo models than seen in normally aspirated engines! This increase
results in quarter-mile time improvements of .2 to .25 seconds, easily
making this modification one of the best "bang for your buck"
modifications for any sport compact car.
Another
great benefit in replacing factory pulleys with underdrive units is
reduced weight. Factory units, also referred to as OEM, are generally
constructed from steel or cast iron. Pulley systems like those found
at NonStopTuning are constructed of aircraft quality aluminum, making
them extremely durable while at the same time much lighter than their
steel counterparts. This increased weight reduction results in less
rotating mass on the engine's crankshaft which drastically increases
the engine's ability to rev up to speed faster. Better throttle response
= big grin on a driver's face!
-FEATURED
CAR: BMW 335i