Supercharger Performance Pulley Upgrade for Range Rover (2006-2009) 4.2L Supercharged

Precision-Machined Supercharger Pulley Upgrade for 2006-2009 Land Rover Range Rover (AJ33S / L322)

Replaces the oversized factory pulley with a 10% smaller diameter unit to increase Eaton M112 blower speeds, delivering a 12% boost increase and approximately 25-35 additional horsepower.

The Stock Range Rover Performance Ceiling

The factory 4.2L Supercharged AJ-V8 is equipped from the manufacturer with a conservative pulley diameter designed for comfort and longevity over raw output. This stock configuration leaves significant manifold pressure on the table, as the Eaton M112 supercharger is under-driven relative to its peak efficiency map. The OEM steel pulley is pressed onto the snout with a clearance that prevents the installation of higher-boost alternatives without physical modification. For the enthusiast, this represents a mechanical bottleneck where the engine's volumetric efficiency is artificially capped, resulting in a linear power delivery that lacks the aggressive mid-range torque these Jaguar-derived engines are capable of producing.

The Engineering Solution

This upgrade features a 10% diameter reduction, manufactured from high-grade alloy steel and finished with a black powder coating to match Eaton's OEM specifications for thermal durability and corrosion resistance. By increasing the drive ratio, the supercharger spins faster at lower engine RPMs, generating an immediate 12% increase in boost pressure. Unlike aluminum alternatives, the alloy steel construction ensures the pulley maintains its press-fit integrity even under the extreme heat cycles common in the L322 engine bay. Installation requires professional snout machining to clear the smaller diameter, but it is specifically engineered to function with the factory belt and ECU calibration. This ensures a significant power gain without the risk of lean conditions or 'Check Engine' lights associated with over-boosting.

Technical Specifications

Compatibility

• 2006-2009 Land Rover Range Rover 4.2L Supercharged

The Land Rover Precision Standard

Engineered for the discerning Range Rover owner, this pulley upgrade provides a factory-clean installation that respects the mechanical tolerances of the AJ-V8 engine family. It delivers a measurable increase in passing power and throttle response while maintaining the refined drivability and CEL-free operation expected of a high-end European SUV.