6% uprated supercharger pulley for Jaguar XJ Super V8 and XJR 4.2 (X350) 2003 - 2007.
These pulleys are CNC machined, produced to the highest dimensional tolerances and surface finish standard of any on the market, and made from high grade stainless steel which retains its superb finish after heating and fitting.
Supercharger pulley upgrades are not only the most proven, but the best value performance enhancements available for your supercharged Jaguar engine in terms of £/bhp.
Changing the pulley ratio results in the supercharger working at a higher speed and producing more boost. Because this just directly increases airflow through the car’s existing sensors, the ECU is kept aware of the increased flow and no further alterations or remapping are necessary.
Boost & Power Increase:
This modification gives a 6% supercharger driven speed increase, which equates to about a 1.5psi boost pressure increase (this is the pulley size which does not require material removal from the supercharger nose, please see our other ads if you prefer the 10% pulley option).
These upgrades have been fitted now to many cars and discussion on forums and bar stools usually refer to about a 25bhp/ftlb gain from this size of pulley modification. That is true for the midrange gain, though the Eaton M112 supercharger becomes less efficient at high rpm so actual peak power gain may realistically be about 10-15bhp. Irrespective of the increase tailing off a little towards redline, this modification gives a HUGE increase in instant grunt and acceleration which really does transform the car.
In some cases, belt slippage has been reported when using smaller upper pulleys but this is attributable to some manufacturers taking a cheap route of making pulleys from aluminium alloy, which loses friction when hot. Our high grade stainless steel pulleys do not suffer from this problem.
- High grade stainless steel CNC machined upgraded supercharger pulley.
- Detailed instruction sheet with stage-by-stage photographs.
Jaguar XJ Super V8 and XJR 4.2 (X350) 2003 - 2007.