www.jec.org.uk

I`ve recently fitted a small 2.5lb boost small supercharger pulley to my newly acquired X350R.

This gives increased boost and lower down the rev range power increases of up to 40hp with no detriment to drivability. A K&N type or similar free flow air filter also adds up to 10hp. It is a useful mod which can be done by a well equipped and knowledgeable person. However, I would class the work as relatively complex and not anything like as easy as simply relining brakes or dropping engine oil. Its rather more than that! The work is one for an enthusiast with a desire to want to slightly modify his car and gain extra power and torque.

The details of the modification I carried out have already been posted in a thread previously and putting this link here gives a direct and accessible link to this type of modification in future years. Doing this also saves me from having to type the same thing out all over again!

http://www.jec.org.uk/forums/viewtopic. ... 9&start=15

Mike K

Here is an appropriate link to the British Parts site where they list the modified supercharger update kit for the 4.2 S/C engine. This kit is a Jaguar recommended update originally sold to cure belt squeak. However I am told it is able to stand higher charger loads and is recommended to deal with cars that are prone to flinging drive belts off. Anyone fitting a small supercharger pulley really should also install this kit as a matter of course to ensure the S/C drive belt does not get flung off the original factory fitted smooth surfaced and shoulder-less idler pulley arrangement. That has been known to occur with even the standard sized S/C pulley still fitted. (7mm larger in diameter than a super small 10%/2.5lb after market conversion unit) The price including delivery is around £199. I wish I`d known that BP stocked this kit before I hurtled over to a Jaguar Main Dealer, who even with JEC discount charged me £272! I`ll not be making that mistake again. No more Main Dealer supplied parts for me.
https://www.google.co.uk/url?sa=t&rct=j ... JEu6g8XRjw

The mod kit includes a new automatic sprung loaded tensioner, a new double sided ribbed drive belt, a modified fixed pulley bracket (I measured old against new and the new part was 0.8mm shorter than the old part. You could mod the old bracket but it isn`t worth the bother) and most significant of all, a ribbed and shouldered rather more substantial fixed idler pulley. The plain flat shoulder-less pulley was responsible for throwing and wrecking two drive belts in quick succession on my car. Included in the kit is a drive belt which has ribs on both sides. The old style belt had ribs on one side only. The new belt is thicker in cross sectional area and looks as if it will stand a fair amount of punishment.

Mike K