I found a really nice 97 XJR with 105k and I'm very interested in it. But how does the XJ12 compare against the XJR6? What performance mods are out there for the XJR? Would love to have an XJR8 but they're out of my price range for the non nikasil ones. Also, fuel economy for the XJR6 vs XJ12, thanks guys!

 

The XJ12 is a gas hog. The XJR6 can be because you will want to put your foot in it. Performance-wise, I would say the R is the hotter of the 2. The 12 has upper end power only. The R has power throughout the range.

My 2¢.

 

Okay got it, thanks. What kind of highway mpg would I see going 65-70mph cruising on flat roads? I'm trying to get as much info as I can on the XJR, what I love so far is that its an inline 6, stronger than a v8 (design), supercharged, and has a 4l80e, might be able to swap in a 6l80e when they get a little cheaper. What kind of power can the AJ16S make/take on the stock internals? Can you name a few websites I can go to for some aftermarket performance parts? Sorry for all the questions, I just can't believe I didn't look into XJR's earlier, they seem so much better than my other options (E38 740IL, w124 s500, etc.) Thanks again.

 

My opinion varies a bit from Ken's...which almost never happens :-)

The 6.0 V12 has nearly the same torque as the XJR/6....and wayyy more than the old 5.3 V12s, plus they come with a 3.58 differential in the X300s...rather than the 2.88 ratio as on the older models.

In pure zero-to-whatever acceleration the two cars are virtually identical.

Still, it's really hard to beat the prodigious torque of the supercharged 4.0. No matter what gear your in or what road speed your at, the torque is just "there".

There is very little by way of aftermarket hi-performance parts for the XJR6...virtually none, actually. The few XJR/6 guys wanting more power usually do a lot of home engineering on improving the intercooling and such. There is a timing modification that helps (I have it) and I went from the standard 3.27 differential to the 3.58 used in the V12s and the standard 6 cylinder cars....it made a good difference.

In the USA all the V12 X300s came with the soft-ride suspension so the the XJR is quite a bit better as far as cornering goes. It has a fairly tight suspension as luxury cars go. You can hold your own quite well on the twisty stuff but it takes some effort....you can't toss around a 4200 pound Jag as though it was a Lotus.

If I drive gently I can get 23 mpg on the highway (USA gallons) and about 15 in city driving. Lop off about 10-15% for ....um....spirited drving. Lop off 50% if you're really rompin and stompin.

Cheers
DD

 

A little bummed there's no mods out there, what about the XJR8? I read that if the nikasil blocks are still healthy then it should be fine from now on since we don't use sulfur in the fuel anymore. They're just as cheap as the XJR6's nowadays. The gas mileage doesn't seem too bad, around what rpm are you at going 65-70? Sorry for all these questions. One of the things that scare me the most about the XJR8 is their transmissions. Could I swap a bellhousing and use the 4l80e? Maybe once the mercedes tranny gives out I can drop a 6l80e in there? If not then 100% I'll stick with the XJR6. I've already gone through 2 ZF transmissions on my 7, and the 325's is starting to act up too. I really appreciate the help.

 

I think there's more out there for the XJR/8 becuase there are more of them around and the're fast enough to begin with to be of interest to performance enthusiasts. A lot of people, even enthusiasts, don't even know the XJR/6 exists. Still, though, even for the XJR/8, there just isn't a really huge aftermarket performance parts network as you'll find with more common/higher production makes.



About 2500 at 70 mph



From what I've heard you have good reason to be scared. They're very expensive to repair/replace....but that's just heresay on my part. I've never owned one.



I doubt it. Either would have different electrical architecure and where would you get a bellhousing adapter?

Bear in mind that the 4L80E isn't the world's longest lasting trans. I mean, there's nothing bad about them and they'll hold up to lots of power....but they are not particularly known for lasting forever and ever.



My XJR/6 has been very good to me so far although they do have some quirks. The only problem I've had that's really worth mentioning is needing to replace the differential at 70k miles....a bit disappointing to need it so soon. But, OTOH, I run the car pretty hard.

The six cylinder Jag engine is really durable and the car itself is built like a tank. They're not perfect but there's plenty to like about them...and, as far as used cars go, you'll never find more car for less money.

Cheers
DD

 

Was hoping it would be at a lower rpm lol oh well. Yeah I would hate having to replace one of those trannys. I forgot the website but there's one that makes standalone ecu's for the 6l80/90e's, all you have to do is hook up the solenoids. True but they can be built to handle some crazy power, rebuilt for cheap, and found for very cheap, especially around where I live, the 4l80e, 6l80e's are still a bit pricey. That's good to hear though, love a nice torquey inline 6. Rear ends are nothing new to me, replaced 2 on the 7 and one on the 3 already, but I beat the **** out of my cars, I'm more than happy with 70k. The XJR definitely seems like the most bang for buck right now, don't know how I missed it for so long.

 

Try dropping into the Engine section, lower down the forum. The guys in there are all into getting better peformance etc.

 

This has been an interesting topic and I think let's move it off to the Engine Forums
Once I had been an XJR 6 , boys that was an awesome machine and acclerating like a rocket .
I am a V12 lover but I think R outperforms V12 in every way

 

Cool thanks, well I've set my mind on the XJR8 if I can swap a 6l80e into it, if not, then it's the XJR6, again thanks for all the help!