Hi Guys. Finally got the top super charger pulley fitted. I bought it from Powerhouse Automotive in UK. Its the 10% increase one. Should give 2.5-3 psi increase and approx. 35-40bhp. I will verify this when I get the Dyno done in a couple of weeks. I have uploaded the pix as best as I could. We decided to remove the super charger to grind the snout more accurately. Gives a proper finish. The scariest part of the job was heating the pulley to fit the super charger. I have to say I can definitely feel a difference in throttle response. Much more eager and aggressive. Its only been day 2. So need a little more time to fully test it out. When I get the 2nd dyno done I will post the comparisons and see just how much of an improvement this mod has achieved.

 

Sounds like you did a dyno before and intend to do one after. Good method to determine gains. I'm curious to see if you really going to get the HP gains you are hoping or, will the ECU dial the boost back to factory normal? Nice series of pictures!

 

Hi Muncher, I got the same pulley from PH UK. I hate to break it to you but my test was b/4 and after 1/4 miles and they were practically identical. The power gain your feeling is actually the boost spooling up sooner with the smaller pulley. I believe the only way to get the full benefits is with an ECU tune (my next mod). I'll be going with the Viezu pulley and exhaust tune since I also have Milltek HFCs.

BOL
PS I'm amazed you got the Supercharger out, I did mine right on the car b/c it seemed there was a nut on the underside I couldn't get undone.

 

anyone has done the comparison between a pulley modded xkr 4.2 and a standard 5.0 xkr.
I checked several tuning companies and the 4.2 with ecu without pulley would do a 470bhp and 650nm (420bhp and 560nm), the 5.0xkr goes for 510bhp and 625nm standard or 560bhp and 700nm also tuned ecu.

for example:

Jaguar XKR All 4.2 V8 Supercharged - BR-Performance - Professionele chiptuning

Jaguar XKR All 5.0 V8 Supercharged - BR-Performance - Professionele chiptuning

So what would be the difference in driving between a standard 5.0xkr and a ecu tuned 4.2xkr???? Or a standard 5.0xkr against a 4.2 pulley and ecu optimized one???

now I'm very curious

 

I have to say the low to mid range is where I have noticed the most improvement. Which is exactly what I was hoping and expecting.
Mike you are correct with the ECU tune. That is on my next to do list.
I ran a before dyno run. In a couple of weeks I will do an after dyno run. This way I will see just how much of an improvement I got with the pulley change. Then when I get the ECU tune I will do another dyno run to see how much that also improves things. I guess the dyno guy is going to love my repeated visits. He is giving me a discounted rate so can't complain.