What's an underdrive pulley?

An underdrive pulley is a replacement pulley that bolts up the same as stock, but has a different size (ratio) and material specifications intended to free up lost horsepower. By increasing the diameter of each accessory pulley and decreasing the size of the crank pulley, the speed at which the accessories are turning relative to engine RPM decreases.

Under drive pulleys do not add power to the engine, they free up the power that is normally wasted on overdriven accessories. The theory is that a larger pulley will drive the accessories slower thus reducing their parasitic horsepower loss. No more power total, but more power sent to the wheels. As an additional benefit, the reduction in wear (less usage) on the accessories due to the lower duty cycles can extend the life of these parts.

For example, the alternator, power steering, water pump and air compressor rob horsepower from the engine. By replacing factory-sized harmonic balancer pulley with the MOTOBLUE resized SFI. approved 25% reduction crank pulley and harmonic balancer, the accessories are slowed, resulting in more horsepower available to the drive wheels.

MOTOBLUE™ GEN X 25% underdrive balancer for 2005-2008 5.7L/6.1L Dodge Charger/Magnum/300C including 2008 SRT-8 Challenger incorporates a number of high quality features you won't find on any other aftermarket unit and makes up to 12 additional rear wheel horsepower and 20 ft-lbs of rear wheel torque over the stock crankshaft pulley. Pulley features are a pair of extra tall belt retention walls that eliminate the belt slippage issues common with other balancers. Other unique design strengths include a 100% steel construction (other brands use aluminum), integral timing marks and built in puller mounting threads. Includes detailed installation instructions.

Installation: Requires new belt - Dayco 6PK2025 or similar.

Tech Notes: Use of harmonic balancer puller/installer tool required for factory harmonic balancer removal.

PowerForce+Plus Performance Dampers
5.7L and 6.1L HEMI

The PowerForce+Plus performance dampers are among the very few high performance dampers available for this engine and by far the least expensive. Pro Products Powerforce model for high performance street applications is one of the only damper of this type available for this engine.

The Powerforce+Plus is designed as a racing damper (but is more than suitable for street use as well) and meets SFI specfication #18-1 which is a requirement at most racing venues. As with all our Powerforce high performance street dampers, this model is made of tough nodular iron while the Powerforce+Plus SFI spec racing model is made of 1045 steel, both the hub and the ring.

These dampers feature a special high performance elastomer bonded to the metal, bolt in counterweights that are accurate to +/- 2 grams, accurate crank bore for a precise, press on fit, and less than .005" runout. Most dampers have 60 degrees of bright white timing marks against a high quality, semi-gloss black finish, and both the hub and the inertia ring are made of tough 1045 steel on SFI spec dampers, and nodular iron on street dampers. Weight: 7.3 pounds