6% Uprated Supercharger Pulley

The Powerhouse Jaguar XJ Super V8 / XJR 4.2 Supercharger Upper Pulley is a performance enhancement for the X350 chassis, specifically targeting the 2003-2007 model years. Manufactured from high-grade stainless steel, these pulleys are CNC machined to the highest dimensional tolerances and surface finish standards. This direct-fit upgrade increases the supercharger's driven speed by 6%, resulting in approximately a 1.5psi boost pressure increase. The increased airflow is recognized by the existing ECU, meaning no further alterations or remapping are necessary for proper operation. While some discussions suggest gains of up to 25bhp/ftlb in the midrange, the actual peak power increase is realistically estimated between 10-15bhp due to the Eaton M112 supercharger's efficiency at high RPM. Despite this, the modification delivers a substantial increase in instant torque and acceleration, significantly transforming the driving experience. Unlike pulleys made from aluminum alloy, which can lose friction when hot and cause belt slippage, the stainless steel construction ensures consistent friction and belt grip. The sale includes the high-grade stainless steel CNC machined upgraded supercharger pulley and a detailed instruction sheet with stage-by-stage photographs. Compatibility is limited to Jaguar XJ Super V8 and XJR 4.2 (X350) models manufactured between 2003 and 2007.