Very nice times �� what tires are your running? I think I about had it with street tires as I can not get any lower than 1.9 60ft

 

I’m running Michelin PS4S, I absolutely love these tires

 

Well there's track and then there's Slalom.
Here's a shot from my best time of 45.162 on the standard Jaguar Club of America Slalom (aka autocross).
And yes the cone fell back exactly into place and there was not penalty.
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You dreamed of a big star -
He played a mean guitar -
He loved to drive his Jaguar...

So welcome to the machine

 

Those are great times! How did you launch the car? Dynamic on/off? Traction On, Trac DSC, or Traction Off? Transmission in D or S? Accelerate from 0 RPM or Brake-torque to a certain RPM?

I have a really tough time launching the car even with stock power, the best I could do was 12.804 at 114 MPH. So very interested to know your method.

 

I have tweaked and tweaked my launch over the last couple of years, to get me to where I was yesterday, which I think was a flawless launch, without going with something more agressive, like slicks...

1. I will drop tire, pressure, gradually as I noted in my post from yesterday, I find that somewhere between 28 - 30psig, ends up yielding the best launch without impacting top end speed.
2. I place car in dynamic mode "checkered flag"
3. Shifter into Sport "S"
4. Traction Control Fully Off, so hold down for 10secondes, or till it says DSC Off, see item #10 below.
5. I will do a small burnout, to clean off any gravel/ dirt, and to get some heat in the tires
6. I will stage the car (so both sets of light are on).
7. Hold the brakes firmly with my left foot, and immediately start to bring up the revs to ~1000 - 1200rpm, I use sound to gauge where the engine is revving, I don't confirm with a visual check, as I'm too busy focusing on the lights.
8. When the 2nd Yellow light illuminates, I release the brake, and slowly start rolling into throttle. It's a process best described, as you have to feel for traction, you simply keep giving it more and more, assuming you're not slipping. This is a case where less is more. Rev up too high, say 1500rpm or 1800rpm, and you will spin, roll into the throttle too quickly and you will spin (like I did with my 2nd run yesterday). If I can launch a RWD ~700HP and ~700lb-ft of torque (assumed figures at the crank given my WHP and Wheel Torque numbers), and register a flat 1.80 60 foot, where an AWD lighter car (F-Type) on the same tires registers a 1.78 60', that tells me I'm doing pretty good.
9. Once your foot has gone gradually to the floor, stay in it, till you pass the end of the 1/4 mile, then let off, and start braking.
10. If at any point, your back end starts to go squirley/ let loose, let off immediately, do not brake till the car has straightened out. I should point out, all of last year, I never went down the drag strip without traction control always fully on. I would turn it off to do the burn out, then quickly turn it back on, it was only in error that I left it fully off, and it yielded my best run. I have been going to the drag strip with different cars over the years (~15+ years), and even still I did not feel comfortable taking traction control fully off, till I saw that it actually yielded a better time. I will say to everyone doing this, to exercise extreme caution and to stay safe.

 

Thanks for the tips! Your 60ft is hard to achieve with that amount of power and on a street tire. I'll just need to keep going back more often and gain these skills.

 

No matter how I feather it in, either I brake loose and spin most of 1st gear or I launch at around 1.9 60 ft mark, any faster than this and my tires loose traction. I suspect I need drag radials , have been through Hankocks, Continental contact extreme , now on Bridgestone re71r , same results on all of them. Wish I had the money to keep testing tires

 

Congrats on the times for your last outing and thanks for the tips. I would really like to improve on my 1/4 mile and 60' times in my '10 XKR but suffer from traction issues even with PS4S's. I drop mine to 15 psi so it is interesting to hear that you leave yours so high. I wonder whether the extra weight in the XF helps take off?

I have tried all combinations of dynamic mode, sports mode and traction control and find that Winter mode + Sport + Trac DSC get the best results for me otherwise I just get too much wheel spin. The 60' times suffer because of it though.

I did some runs a couple of weeks ago but my best 60' time was 1.96. Most of them were over 2 secs. I did get one run in the 11's but the rest were in the low 12's and the best terminal speed was 122.52.

Someone asked me if I had an open diff because when I was doing my burnouts only one wheel was spinning with TSC fully off. It can't be helping if only one tire is getting some heat in it and there is usually around an hour between runs because they have so many cars and different classes to get through so the tyres are cold and the engine has heat soak when I start my runs. I tried doing one burnout in Trac DSC but the car just bogged down and wouldn't let me spin the wheels much at all. It is a shame it seems so happy to spin them though when I am doing my runs!

There is another meet in a few weeks so I will have a go with some of your settings.

 

Spring for the Michelin PS4S Tires, or Cup 2's and you will not have any issues with traction. I had the Dunlops, the Pirelli's, the Hankooks, and none compare, it is simply amazing what the traction is like with the PS4S.

Two things here, first I haven't looked at my car when doing burnouts, but I'm positive I light up both, which has me asking why you are only spinning one tire? Is it possible your E-Diff isn't doing what it's supposed to? You will never launch properly if you are simply spinning one tire.

Second item, is I have tried launching the car with all three traction modes, DSC on, DSC Trac, and DSC Off, and hands down for me, the slowest is DSC Trac, the most consistent is DSC on, as you rarely screw it up, but it's not the fastest. When you get everything right, DSC Off will yield the fastest launch. This is contrary to what I was saying in this very thread earlier on, only till about a month ago I was adamant that I had to brake boost to 1500rpm, and slowly role into the throttle but I would say given my experience last Sunday that less is more.

Also I recognize that the XF and the XK are two different cars and that the XK is lighter, and the XKR might have different suspension geometry that may change this, but I would think if it's more softly sprung especially in the rear, then that would aid traction not hinder it (again, I'm assuming the XKR is softer than my XFR-S, I do not know for certain).

I have never tried to launch the car in winter mode, heck I do not think I have ever put this car (XFR-S) into winter mode, I would say that I might try it, but it will have to wait till next year as the car is already stored for the winter, which came swiftly on Monday, literally the day after I came back from the track.

 

Good question. I assumed that with traction DSC off the E-Diff would be disabled as well but I can't find anything to confirm or deny that in any of my technical manuals.

My wife is threatening to come the the drag strip next meet so I will get her to take some videos so that I can see what is going on.

I also have an app on my phone that can monitor output from the E-Diff so will have a play with that and see what the readings are for torque demand, clutch temperature, oil temperature etc in the various modes. I actually scanned it today and there aren't any errors relating to the diff.

 

sir, your writeups are inspiring! i believe you've previously stated owning a 6 speed xfr, correct? can you comment from memory on launch differences between the 2 transmissions? I've had only a handful of "full torque" launches with my car and none of them on the track. that's not to say less than full pedal used, but seems to cut power and bog to easily, especially as i "shock" the tires with too much too fast. so I'm finally gaining understanding and experience with rolling into the throttle. actually much easier since i realized i could put my heel at base of the throttle and that changes the fulcrum point substantially from my normal hinge point with heel in floor mat. i've only achieved a 12.47 second pass, at a low 111.61 mph.. on ps4s's in 295 width. the 60' time was 1.97.. it must have been the same bog off the line. that's the inherent problem - the bog - sounds like you experience same if you launch incorrectly, but i was wonderign if you feel the 8 speed allows more torque to the tire as opposed to the 6 speed. PLUS I'm FAT

 

111.61 mph trap speed on a VAP tuned 5.0 seems low. I have never ran lower than 114 mph on my stock XFR which has the 6 speed, but my lowest ET was 12.804. I suck at launching the car properly and that results in my 60' time always being 2.20+. I have the Ventus V12 evo2 tires, which are not nearly as good as the PS4S, but there is a youtube video of someone running a 12.395 with these tires. So I can't fully blame the tires.

 

agree. trying to rationalize why that was, but i may have let off - cuz dumb and wasn't sure where end of track was and it's already a lot to slow down from almost 120mph.. i have had a few in the 113 range with slower ETs. Just reinstalled under tray panels that have been off for 2 yrs.. maybe added drag with those panels off?

 

As I stated earlier in this thread, that even though I had done a lot of modifications to my 2012 XFR (with a 6spd ZF auto), I never ran that car at the drag strip ever, I had launched multiple times, and there was a comfort to how easily and predictable I could brake the tires loose, in day to day driving, but as far as launching it for optimal 60' times, or ET or trap speed, I don't have any concrete of definitive data. All I have is my very subjective opinion, which is just that...
I did mention that the 8speed in the newer cars (I believe from 2013 on wards in NA), is leaps and bounds ahead of the 6speed, and that is saying a lot, as I never had any concerns with the 6 speed ever. Everything from the shorter gear ratios down low, to the taller gear ratios, especially for 8th gear, give you the best of both worlds, rapid acceleration due to the shorter gearing, and better fuel economy due to the taller gears up top. You should factor in that your track's elevation, and your ambient conditions will have a great effect on your trap speeds, so with out that data, it becomes impossible to compare if 111 or 112mph is too slow...
According to Motorweek, a 2010 XFR stock could do the 1/4 mile in 12.9 @ 112mph, see link: 2010 XFR 1/4 mile - Motor Week

Again comparing different results from one track to another, or seeing a video on youtube, without have the definitive conditions of the track and weather, makes it difficult to determine if the better results were due to better ambient conditions (elevation, temperature, etc), or better driver, or better track prep (how sticky was the track?)

If I look at the very first post with my car running slightly over stock (for a XFR-S mind you, so close to 600BHP), car stock is ~550BHP, and put down 500whp on a dyno, with the upper pulley and my old Rica Tune, I had put down 540whp, which I'm assuming is ~600BHP. I also had the crappy Pirelli P-Zero Tires, which are horrible when compared to the PS4S, and I ran a 12.5 @ 115mph, with a 60' of 2.078secs. Unfortunately when I went back to the track, I had changed too many parameters, tires (305 PS4S, in lieu of the 295 Pirelli), lower crank pulley, same tune though, but the lower pulley makes a huge difference... I ran a 1.89 60', and immediately dropped into the 11's, running a 11.97 @ 118.8mph... I would say the better launch was down to the tires, the better ET and Trap speed, was a combination of better launch, plus the added power of the lower crank pulley

 

yesterday - only 2 passes b4 they closed,, personal best et/mph with poor 60' still. i think the car has a 12.19 in it... next year

 

I went back to the track today and took on board some of your suggestions. I kept the traction control fully on though but used non dynamic plus sports mode rather than snow mode and smashed my previous best.

There was a national competition being run so I think they spent extra time prepping the track and the difference was incredible. Little or no wheel spinning and I was startled on my first run as to how hard the car launched and was surprised to get an 11.764@123.31 mph!

I therefore tried a harder launch for my next run and got an 11.645@123.09 mph but then didn't get another run for over an hour and a half because they wanted to get the competition cars through.

I thought the track may have gone off by then because it was warming up and lots of cars had gone through but I managed to do a new personal best of 11.567@123.19. The 60' was a new best as well at 1.756 and I think I would need drag radials to improve on that!

 

Not bad at all Adam!!!

I replied to you on your other thread, but I'll say it again, that is a great result!!!! I think you are finally seeing what your big cat is capable of. All around great numbers!!!! Congrats again.