After downloading the 2011 XF technical data sheets from Jaguar, I noticed that the maximum boost pressures listed for the SC model is 7.3 psi and for the XFR at 10.2 psi. Is this due to different pulley sizes? Or is this difference somehow programmed? Any help appreciated.

 

My vote would be in the programming...

 

The lower pulley seems the same on all the models (according to the parts catalogue). So if there is a boost difference, it is probably via the upper pulley, but I can't check that. Boost difference would only be done via pulley changes on supercharged engines, and not via software as on turbocharged engines.

 

That was my initial feeling buy still haven't checked Jag part on the upper pulley #s yet. I've emailed Spires but not a word. Thx.

 

Best chance to find out is that an owner is kind enough to measure the size of the upper pulley as Jaguar doesn't list the part separately.

 

Forgot to ask, where did you get the info about the different boost levels?

 

My neighbor has a 2010 XKR, He said he will try to measure the size of his vs my XF SC to see if there's a difference once he get's back from work.
If there is a size difference, I wounder how hard would it be to just put on the smaller pulley? What else would need to be done after the pulley change, if it is possible to change the pulley?

 

Finally found it: http://us.mediajaguar.com/php/mediak...p?section_id=3
On left, highlight under XF "Media Kit"; on small screen change, pick language and then download. 3 files, double click specifications.

 

That would be great! As I understand it you don't have to re-tune/re-map the ecu as it will relearn under operating conditions. I also understand that the upper/small supercharger pulley can be quite difficult to remove but one of the UK vendors has the proper tool. You can reuse the existing belt.

 

Well my neighbor attempted to check the size difference.. Not much space under his hood betwween the SC and the radiator. It does apppear to be a size difference. He could not exactly tell how much, but the supercharged XF pulley is alittle bigger.
It would be interesting to see if anybody have changed their pulley, and if they did see a difference in PSI.

 

The pulley will determine the speed of the supercharger and thus pressure, so here would be an easy gain to be had.

 

Would love to see if anybody have made the change and what gains they received from it. I would also love to find out how difficult it was, to make the swap.