Hi Chaps,

I have recently purchased an XJR-6. There are pictures here: (if anyone is interested)

https://www.jaguarforums.com/forum/n...e-pics-111862/

It seems to be in great shape, runs smooth, all fluids fresh, no nasty noises, great service history BUT its seems to be down on power (i imagine)....

Its fast once up and going (on a dual carriageway etc) but last night on very wet roads, i turned the traction control off, put her in sport and gunned it at 20mph and it didn't even light the rear tyres up (4.0 XJ8) would have wheel span relentlessly if i had done the same thing.

Likewise, in the dry from a stand still - TC off and no wheelspin (unless i have some steering angle (i.e coming out of a junction)

Now i dont intend to drive the car like this most of the time, and i didn't buy the car to go sideways everywhere BUT its current lack of 'hooliganism' must surely be a sign that something isn't right??

The only thing i can say is that there seems to be a noticeable amount of throttle pedal travel before something happens (although this doesn't seem that noticeable once up and running)....

I recorded these videos earlier (Both on VERY wet tarmac)

The first one was with the traction control on and not in sport mode (0-60 in 8 seconds)

The second one was still with the transmision in Sport mode, but with the traction control on (you can notice it cut in at 2000rpm) this again gave 8 seconds.

https://www.jaguarforums.com/forum/n...e-pics-111862/

 

Sorry - Here are the links to the video clips.

 

Wellllll.....the XJR/6 does have a limited slip diff, so the tires will never spin as much as a similar car with an open differential such as an X308/XJ8



I'm inclined to agree.

Mine will certainly burn rubber if tromped *hard* from a dead stop. Depending on tires and road surface this varies from just a couple 20 foot black streaks on the asphalt to lots of tire smoke and the car slewing slightly sideways.

Tire size and compound really does make a difference, though.




The cables are easily adjusted to take up that slack. Doing so would be a good first step!





I couldn't make the videos work but contemporary road tests show 0-60 time of about 6.5-6.7 seconds so yours does seem slow-ish. A 1.0-1.5 second difference is significant

Cheers
DD

 

The difference is that the XJ6/R has a real limited slip diff. It actually turns power into motion instead of burning up one tire. Enjoy it

edit: I see Doug addressed it more comprehensively

 

OK, just tried the videos again...they work.

One thing I notice is that the 1-2 shift seems to be at 5000 rpm. Mine runs right up to the 5500 rpm redline before shifting.

This doesn't relate directly to off-the-line ooomph but still suggest that something ain't quite right.

Do adjust the cables and also check the supercharger belt tension. Might be slipping.

Also....I almost forgot.....check the coolant level (cold engine) at the intercooler plug. There might be an air pocket and/or simply low coolant level.

Also, the intercooler pump may have failed. Mine did, years ago. If the intercooler system isn't working right you WILL feel a difference.

Cheers
DD

 

One more thing.....

I had to replace my diff at about 75k miles. Afterwards I curtailed my tire-burning activities quite a bit....although a fellow *does* still need to have a bit of fun from time-to-time.

IMHO the diffs used on these cars a marginal spec for the power they're expected to absorb.

Cheers
DD

 

Many thanks for the pointers and advice - I will look at the throttle/accelerator adjustment tomorrow.

Not being in a position to go to the car now - is the intercooler plug an obvious thing to locate? and is there a 'level' there?

 

It's a large-ish plug.....19mm wrench as I recall..... at the very front of the inlet manifold/intercooler.

The supercharger intercooling system is tied into the main engine cooling system so, in theory, if the main system is full, the intercooler will be full.

But.....

I've found, on a few occasions (I must have a slow leak somewhere) that the main engine coolant tank is full but the intercooler isn't. I use a tiny funnel to add coolant to the intercooler....top it right off to the brim.... and squeeze the inlet and outlet hoses to remove the bubbles.

Cheers
DD

 

Install an Andy bracket and open up the intake with a cone filter. You will definitely feel the difference. Should you want more, change the diff to a 3.54 and let the good time role. Should you want even more, install the magnum powers supercharger plate with larger vent ports, this is good for 2-3lbs of additional boost. Should you need even more, install a sc intercooler fan and or chiller killer system. Keep the temps down and keep the horsepower, the intake temps can heat up quickly. Do not open up the exhaust and make it a true duel exhaust system because you will loose alot of bottom end torque and you will not be happy. This is all you can do in order to make your car scream. Or if you can find a cam with more lift please let me know as I would want one. This should be sufficient, after all it is meant to be a daily driver.

 

All great modifications but you're putting the cart before the horse.

The more common and sensible first step is to make sure everything is simply operating as intended ...which might well give the desired level if improvement....and THEN spend money on upgrades and mods if more is desired.

Cheers
DD

 

Doug is right, all recommendations should only be done after all needed repairs are done. You may be happy with stock performance after repairs. I on the other hand like to teach those youngsters a lesson when they pick on me with a lousy civic. The look on their faces is priceless.

 

If you haven't already, take a look at the second video posted by jammapic here https://www.jaguarforums.com/forum/x...00/#post918392

This is the kind of acceleration you should expect. Notice how smooth the needle moves through the rev band and the shift is right at 5.500 rpm.

 

Thanks... I probably should have updated the post to say that:

Having waited for the rain to stop, turned of the TC and put the gearbox in Sport mode. I gave the 0-60 dash another go and found i did a 6.8 (including a little bit of lost time backing off for initial wheel spin) The shifts also changed up at 5.500 (or as near as makes no difference).....

I think initially i was adjusting back to the linear and refined power delivery of the XJR as opposed to the peaky boosted delivery of my tuned SAAB 9-3SS Aero and my Clio RS172 CUP.

All that performance testing took its toll on MPG.... I went down to an average of 10.1mpg!!! Luckily thats not how i drive the car normally :-)

 

Also... I am not sure what (if any) difference it makes.... But my initial testing was done with the fuel that the previous owner had left in the tank. I have no idea if this was regular 95Ron but i run the car on Momentum 99Ron.

 

If the fuel was low octane the knock sensors may have detected pinging/pinking...which results in the engine management system retarding the timing.

Cheers
DD

 

I'm looking to purchase the Mina Gallery intake/cone filter soon. I removed the top portion of the air box and sure does make the supercharger sound lovely.



Jaguar XJ8 XJR Performance Intake for Jaguar XJ6 XJR