...and I couldnt believe how hard it was, mainly to get the bloody thing moving without sitting on the spot spinning up.

My technique consisted of sports mode on traction off and foot on brake waiting for the yellow light, if I gave it over 2k rpm when I let my foot of the brake it would just spin, any less I didnt seem to get a fast enough time, what you think I pulled a 14.05 @ 100.8mph.

My reaction time was 0.57 seconds, do I take this off the terminal time to get the cars time or is it already done?

My only excuse was that I had 3/4 of a tank of feul when I got there and I weigh 120kgs. I think if it wasnt for this and I practiced a bit more I could get into the high 13's??

Good time or not?

 

My car trapped about 101.1 or so at a higher altitude (700ft), so I guess
it has retained a bit more power, or had a bit less heat soak. (10hp
could be easily gained or lost based on the heat of the intercoolers)

Try using a DA calculator on your time to factor in barometric pressure
and temp, and altitude.

I loved your photos! The car looked great out there on the track.

My fastest time (I got 2 runs) was the first one, with traction
control on and was a DA uncorrected 14.1.

I think that you will need to find the stall point on the torque
converter to build revs and let your foot of the brake. In my friends
Challenger SRT 392 (same gearbox) it was like 1600 if I remember,
But it is lower/higher on the sticky track surface I am told (don't
remember which sorry).

The 2 main US mags got 1/4 in 13.7 @ 103.8 and 13.9 @ 103 for
reference. (1998 models)

The 60' times are an indicator of your speed. 2.23 was my best and
that is very poor. (Bad tyres back then) I am eager to run again
and see how it does on my sticky Michelins. A pro drag racer would
expect a 1.8-2 60' time I think for this type of car. Feel for the grip
off the line, rolling into the throttle felt quicker on my later runs (I
only got timed on my first two).

Ian

 

The lack of a limited slip differential just murders our cars at the strip. The best I've ever been able to squeeze out of my 2000 XJR, even on drag radials I borrowed from my buddies C5 Vette, was a 2.09, which is just awful. I ran a 13.90 @ 104 on that run, my best yet. But at that trap speed and a less-awful 60' time like a 1.8, I should be in the mid-low 13's which is more what I expect, and should be possible with nothing more than a posi. Why didn't they just include one?!?!? I'm so tired of peg-legging everywhere trying to get the power down.

 

cabez you are right cant do any serious drag racing without a Limited slip final drive!

we call that one wheel drive!
youd appreciate an all wheel drive with traction control, had ride in a Nissan GTR,OMG! yikes, it knocks the wind out of you on launch.

 

It has been driven 1.898 ( 60ft ) and 12.776 ( 1/4 mile ) without LSD. He used traction control at the launch and then released it.
1998 Jaguar XJR 1/4 mile Drag Racing timeslip specs 0-60 - DragTimes.com

 

I was doing 13.9 in florida in 89 degree heat completely stock, no drag radials(all season tires no less), traction control on. There is a base for you somewhat.

 

If the rear tyres are low on tread & running a high tyre pressure, that that will increase the chances of them spinning uselessly. If your front tyres have more tread, swap them to the rear & drop the rear tyre pressures from 34psi to around 30psi to give a bit more traction off the line.

I've never really gone for stalled converter take-offs by holding the car on the footbrake. I use the handbrake, sport mode, TC off, 1000rpm-then drop the clog fully & handbrake off at the same time, ready to back off the throttle if there is any wheelspin.

 

do you think its possible to lift the front tyres off the ground on a launch, like 3-6" lift?

its very difficult to to do with independent rear suspension, suspension gets all squirrily!


maybe slick drag wrinkle wall tyres.

 

In a word-no.

There's not enough 'moment of force' at the rear wheels to overcome the weight at the front. There's 935kg of weight over the front wheels & the distance between the front & rear wheels (wheelbase) is 2.87 metres.

So the moment of force required at the rear wheels to raise the front of the car is:

935 x 2.87 = 2683 kg/m (kilogram/metres)

Now we need to calculate the maximum 'moment of force' that the XJR can produce at the rear wheels-so we need the engine torque, torque converter multiplication ratio at stepoff, 1st gear ratio & final drive ratio. I'll use the following figures to give a rough ballpark figure:

Maximum engine torque: 387lbf/ft

Torque converter multiplication ratio at stepoff: 2:1

1st gear ratio: 3.59:1 (from Jaguar technical literature)

Final drive ratio: 3.06:1 (from Jaguar technical literature)

If you multiply all these figures together step-by-step, you get the following figures:

Engine torque: 387lbf/ft

Torque converter output: 774lbf/ft (at stepoff, before the turbine has caught up with the impeller as the vehicle starts to move)

Gearbox input: 774lbf/ft

Gearbox output/propshaft input: 2779lbf/ft

Final drive output/wheel torque: 8503lbf/ft

This figure is a theoretical maximum & in reality would be nowhere near this. The torque converter stall speed is typically around 2000rpm so the engine would not have climbed onto it's torque peak. Also, as soon as the vehicle starts to move then the turbine starts to 'catch up' with the impeller & the torque multiplication ratio falls off rapidly from 2:1.

Even if you did achieve the theoretical 8500lbf/ft of torque at the rear wheels, using conversion tables this still only works out at around 1175kg/m-which is not even half of the required 2683kg/m figure to lift the front wheels clear of the ground.

Also, you have to add on to the wheelbase the distance between the driveshaft centre line & the ground (half the tyre diameter)-which will reduce the effect of the rear wheel 'moment of torque' even further...

So no, the XJR will not raise it's front off the ground unless you use a crane