These cars are 1 WHEEL WONDERS (only one wheel turns/Open diff). I think I've done every mode under the sun on the XJR. The one I should've done first if I had it to do over again would be the Quaife ATB LSD. That will unlock the power to the ground. Then after doing that you'll notice all of your upgrades everytime you add on a new performance part. Just my opinion.

 

I live in Atlanta. What color is your XJR?

 

"...WaterDragon's explanation is an oversimplification that would make a physic teacher cringe" <---This is a true statement on both counts.

What I did was accept the eaton's limitations and then did everything else to maximize the flow to and from the eaton. By reducing the vacuum before the eaton by going bigger MAF, intake tube, TB and elbow, I reduced the work load required of the eaton. This is because I understood the eaton basically sucks at sucking. I also reduced the resistance of the air path after the blower because the blower kind of blows at blowing too...it is more of a blower than a compressor.

So yes, the eaton has it's limitations, but you CAN improve the rest of the system to easily get more than the 450 BHP desired goal of the OP in this thread.

Removing 2 psi of vacuum in the intake gave 2 psi more of "free" boost. I say "free" because this was achieved by not making the blower spin any faster. Porting the blower gave another +1 psi, and injecting the water/meth before the blower vs after gave another +1+ psi.

So by working on everything else, I gained +4 psi with the stock pulleys still in place, then adding a +4 lower worked much better. I went from 10 psi stock to 18 psi and the only pulley I changed was a +4 lower, I kept the stock upper.

If I had to do it again, I would leave the lower pulley stock and have Steig do his snake bite kit where he internally re-gears the eaton to a +4 equivalent.

My mods gained me +8 psi. My car did NOT run hot, nor did it suffer from heat soak. Given those conditions of not running hot and gaining +8 psi, it is not possible not to get to or pass the 450 BHP mark.

 

Also upgrade to Buckhead Imports Headers. The OEM manifolds strangle power! I know they are parting out a 01 XJR with there headers on it. I have them on my XJR and they make a BIG difference! Is your exhaust system X piped with muffler deletes? X piping these cars release more HP's also.

 

WD fights his corner very well and provides facts and figures that cant be argued agasint. As I thought theres another 100hp to be had out this engine with simple bolt on's and his car proves this.

Thanks for all your input and information espically you WD, at least some-one bought some optmistic promising info to the thread.

Now I need to find some-one to do the work, I think I'll pritty much follow the advised mod's and let you lot know how I get on. Hopefully the old gal will see high 12's 1/4 mile, only a second to find :-)

 

facts, figures, AND a real world video demonstrated performance

One thing to remember is when adding boost, you are adding timing, and our ECUs are not accessible to retard the timing.
I was running 94 octane and water/meth injection to deal with this.

 

Off topic, what car do you have now WD?

 

L80ous:
I did not mean to imply in any way the car was maxed out, my friend. Only that the consensus is as you have been told, and that is that there is very limited improvement by just upping the Eaton speed. WD has definitely proved that improvements can be made by doing that along with opening the breathing passages. And, I think, that is the point others are trying to make too. I look forward to reports of your results since I am looking for time to get my XJR closer to the XFR performance myself!

VIAPA:
I have one ugly *** faded delaminated black MY 98 with chrome and blackout, and I have a prettier silver MY 99 that I drive regularly. I wish the color was BRG, but, as they say, it is what it is. One of these days I intend to build the MY 98 with better breathing and better brakes, but right now, NO TIME!

 

Is that the previously famous ThuderKitty's car?

 

Still have my Blue Zircon 2002 XJ8. Just about to turn 60,000 miles. Not much to post about since nothing ever breaks with it... Just a pleasure to drive. I really like this car. The blue over tan is my favorite jag color scheme. I'm still helping local jag buddies modify their XJRs and Super V8s.

For fun toys I just picked up this little RED roller skate, a 1992 OBD1 (read easily modified and still smog legal) Mazda Miata. Just finishing up adding the super charger (cute little M45 eaton that just about fits in the palm of your hand) with 9.5 psi boost, water/meth injection, fully adjustable suspension, Carbotech XP10/8 racing brakes, etc.

As fast as my XJR was, this little go cart would push the XJR all around the race track, except maybe in the long straights. I bought a little 2.5 Nitrous bottle for it, but frankly at the 160-170 whp now @ 2200 lbs it is more than fast enough...for now. The parts for the Miatas are ridiculously cheap. Example: I needed to buy a larger set of injectors for the Supercharger and they were, from ebay, $45 for all 4 delivered and they were already cleaned! Yes, just $11.25 each! Those little 14" wheels are only 8.6 lbs each. This little car is a lot faster than it looks. The grip is unreal and the handling is so forgiving at the limits of traction.

 

I would LOVE to know more about this manifold you speak of! Sounds like it would pair nicely with a set of Nameless cats and... well, then we get into the topic of exhaust, and that's a whole other can of worms...

https://www.jaguarforums.com/forum/x...uffler-121149/

This is an interesting read. The centre muffler is more of an H pipe. It's straight through, with perforations that mimic an X pipe.
Also, I have heard that the small mid-mufflers are actually just resonators, and the people that are happiest with their exhaust sound are the ones that have only removed them, and left everything else stock

 

Yes. Thundercat's. I admired what Thundercat was trying to do. I just think he got in over his head. He set the bar too high for his car. You have to remember this is a Ford product at heart with Jaguar's philosophies on luxury and persona. Ford/Jaguar did a good job with the XJR but left no room on the ECU side for adjustments (AFR) like BMW and MBZ does. It's hard to extract proven HP out of these cars like you can with the M5 and E55.

 

I believe we've met. I think at the Wells Fargo on Peachtree Rd and Biscayne Drive. I have a Black R1 and recently bought a 01 Vanden Plas Supercharged that's having some general maintenance done on it.