TUNING

While some tuning outfits will offer a variety of solutions, including legallyquestionable engine ECU remapping and chip tuning, it is possible to make the supercharger spin faster, by installing either a smaller supercharger drive pulley, or a larger-diameter crankshaft pulley, without having to interfere with the standard fuelling and ignition settings.

Lawson Smith reports that he has developed a series of pulleys for specific Jaguar Land Rover applications. While smaller CNC turned stainless-steel upper supercharger pulleys for the 4.0-, 4.2and 5.0-litre models offer an increase in driven speeds of between 5-10%, as well as a torque increase of around 40bhp/40lb ft, he reports that a larger crankshaft pulley for 4.0-litre models is also available. However, he warns against conducting both modifications together, which leads to localised engine overheating, detonation and associated piston and valve-gear damage.

He also advises that the supercharged 4.2-litre engine possesses an 8% larger diameter crankshaft pulley over the 4.0-litre, which can be swapped over. As with the bearing refresh, a competent DIYER can install a smaller pulley without even removing the supercharger.