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 crank balancer/pulley and water pump drive pulley with a resized pulleys, the accessories are slowed, resulting in more horsepower available to the drive wheels.

MOTOBLUE™ H.O. Series pulleys will increase horsepower up to 12 RWHP, and increase mileage by 1 to 2 MPG. MOTOBLUE H.O Pulleys are manufactured from billet steel, exceeding factory quality and are the only Pulley system available on the market today that are SFI approved for all racing applications.

Installation: The kit includes all required components and hardware for a complete installation.

Tech Notes: Use of Harmonic Balancer Puller tool required for factory Harmonic Balancer removal.

MOTOBLUE™ H.O. Series Power Pulley Kit
• H.O. 25% SFI Approved Replacement Harmonic Balancer Pulley
• 22% Short Style Water Pump Pulley
• 8% Alternator Pulley
• Retains Stock belt

MOTOBLUE™ H.O. Series Power Pulley Kit
• H.O. 25% SFI Approved Replacement Harmonic Balancer Pulley
• 26% Short Style Water Pump Pulley
• 8% Alternator Pulley
• Retains Stock belt

MOTOBLUE™ 22% underdrive water pump pulley (billet) 4.2 HP

The Meziere extreme duty electric water pump replaces the factory high drag, horsepower robbing, factory water pump. The Meziere extreme duty electric water pump provides a solid 11.2 rear wheel HP improvement when compared to the factory pump! This pump was designed with the daily street driven vehicle in mind, and it can also be used on fully equipped racecar. Installation of this pump is identical to the factory pump installation, and can be easily completed in less than 1 hour.

This is a direct replacement for the factory belt driven water pump. It comes equipped with a freewheeling billet idler pulley, allowing retention of the stock belt. It also provides an unbelievably constant water temperature under any condition.

• Direct Replacment *



• Solid 11.2 Rear Wheel HP



• Flows 55 Gallons per Minute



• Designed for Daily Street Use



• Unique Impeller Design



• Free-Wheeling Billet Idler



• Retention of the stock belt



• Stock Belt Routing



• Easy 1 Hour Installation



• Detailed Instructions Included