Porsche Boxster 986 Lightweight Underdrive Crank Pulley - $200 shipped

While the stock crank pulley is made surprisingly light, the smaller diameter of this pulley allows the rotational mass required to turn it to be only two-thirds of what is required to turn the stock pulley. While this gives a slight increase of power, the majority of the increase will be from the underdriving of the accessories.

The Cheetah pulley is 20% under-driven, as this is the best compromise of power and drivability. There are not any problems of battery charging, coolant temperatures, or steering assist in a normally functioning vehicle.

Testing has been done under full electrical loads for extended periods without any drops in charging capability.

The added benefit of this Cheetah pulley is that it remedies the problem of the stock Power Steering Pump overheating during spirited driving, such as time at the track. The Power Steering Pump being driven at these lower rates keep it running cooler, without any difference in steering feel.

With the smaller diameter of the pulley, a shorter belt is also needed. This belt is a 6PK2087 belt, which is a 6-rib, 82.2 inch long belt, commonly found at most automotive stores for around $20. The bolt that holds the pulley in place is a one-use-only bolt. It should be replaced whenever it is removed. This bolt is Porsche part number 900.082.085.09 and is normally found for around $3.

Horsepower increases should be up to 15hp at the crank, and this estimate has been verified from dyno results with other similar pulleys. This pulley is intended to work with any Porsche that has a stock pulley number of 996.102.115.63.

The Cheetah Light-Weight Underdrive Crank Pulley offers the largest pulley possible, with a high polished finish, at a low price, and with the largest increase in power through the highest under-driven percentage without sacrificing drivability.

OTHER PORSCHE BOXSTER CHEETAH PRODUCTS:

POWER STEERING UNDERDRIVE PULLEY

SOLID DELRIN FRONT MOTOR MOUNT

POLYURETHANE FRONT MOTOR MOUNT

ALUMINUM REAR SUSPENSION BRACE

Underdrive pulleys achieve both of these goals with a two-fold approach.

Stock accessory pulleys are usually made of heavy, cast steel. They are produced to be made at the cheapest possible price. These steel pulleys require a significant percentage of an engines power to rotate them. Using lighter Aluminum alloys, along with detailed machining processes, the pulley can be made as light as possible; requiring less power to rotate it. This recovered power is an increase easily seen on a dyno and felt during everyday driving.

Also, these pulleys are made with a smaller diameter than the stock pulley. This rotates the belt driven accessories at a slightly slower pace (around 10-13% slower). Since each accessory takes power to turn, hp and torque are regained through the "underdriving" process also.

Typical hp increase are around 5%. So for a 200hp engine, an increase of 10hp is easily possible.