I've put this run up on dragtimes.com

2005 Jaguar XJR X350: 13.254 @ 105.440 MPH

 

Nice run.

Not that I want you to post a faster time than me but....you might consider a set of Nameless performance high flow cats, should give approx 20 rwhp.

Maxbore.com will bore your TB for $100 USD+ shipping, maybe 5+ hp

I noticed a big difference when I switched to a larger 92mm maf.

Drag radials would help too.

Do any 2 of the above and you ought to be solidly in the 12s.

Nice looking car you have there. I'm envious of your aluminum body panels.

 

Just an update on my times, after sorting out the overheating issues I got down to the local track (WSID) last night for a final shakedown before the Snowy Mountains 1000 this weekend.

Only got four runs in as it was a big turnout.

13.309 @ 107.09 with a 2.040 60'
13.245 @ 106.36 with a 2.010 60'
13.314 @ 107.21 with a 2.050 60'
13.352 @ 106.86 with a 2.064 60'

I'd dropped the rear tyre pressure to 28psi cold, it seemed to help a bit with traction off the line, not that the 60' times reflect that.

The trap speed is up 1-2mph from previous runs so the car is making a bit more power, just can translate that into a faster ET.

I was running 3/4 tank of fuel, whereas at Santa Pod it was with only 1/4 tank.

It's pretty consistent now so I think it's not gonna go any quicker without cash injection.

 

Against my better judgement, I took my unmodified '07 XKR to a drag strip in July. As you can see from the photo there is still snow on the hills and there was little sun so the track was cold which meant that it was very hard to get traction on the thick rubber deposits left on the start line.

The XKR is very quick to spin the rear right wheel when traction is low so much lesser cars would easily beat me off the line but once the tyres hit the race circuit proper things changed very quickly! The electronic diff in the later 5L XKR's must make things easier although my '89 V12 XJS had an LSD and one second you had full grip, the next the rear of the car was trying to overtake the front.

I managed to do about 10 runs but couldn't better 13.501@109.89 with a 2.37 @60. My nemesis was a 2004 Mercedes E55 AMG. I beat him once but generally he pulled a nose or two ahead by the finish line. As it had a 5.4L engine with 470bhp, the XKR held its own pretty well. I have a new respect for the AMG cars though.

Video of one run can be found here:


I quite like the supercharger whine and exhaust note at the end

 

I got some pictures from Badger Photography, click on them for a BIG version

 

Actually, I now have proof that it does make quite a difference in power, and pretty much no difference to the intake temps.

I put the flap back in, and went for a drive, the IAT1 temps (at the MAF) were just as high as without it. Sitting idleing in traffic the temps climbed just as quick as without the flap installed.

But, the car felt sluggish & less responsive, it didn't kick down gears & give you that big shove in the back either. It felt like it lost a fair whack of power too.

Put the car on the dyno this morning at CHE (with the flap still installed) and it did this....



Yep, 317.5HP at the wheels, that's down from a previous dyno at CHE of 324HP at the wheels (back when when the thermostat was jammed shut)

Popped the intake off, removed the flap, and did another run;



Hello!

From 317.5 to 329.9 at the wheels, just by taking the flap out of the airbox.

Kind of hard to believe actually. I reckon that the solenoid in my airbox is stuffed & not opening the flap. So better that it's out!

The new 4WD dyno at CHE apparently reads a few HP higher than the old 2WD one, which was supposed to be a low reader.

It's still ~10rwhp less than what I got from that run in the UK, oh well...

Heading down to the track tonight, have just 1/8 tank of fuel, I emptied the glovebox, centre console, took out all the crap from the seat pockets, took out the floor mats, the spare, jack, tools, and the boot floor (which is surprisingly heavy). I also ate nothing all day so it's as light as it's gonna get without removing the seats.

So it's 12.99 or bust!

 

Sure looks cheaper to remove the flap than fix the solenoid!

 

I'm surprised the track doesn't require helmets. ? It's nice to see XJx cars at the drags.

BTW, a well-known speed secret is if you converted your car to left hand drive it would be faster.

 

The first pics in the thread are from Santa Pod in the UK, you don't need a helmet there until you trap 110mph. Here in Australia a helmet is compulsory.

Hahaha, I bet if I put it on a dyno in the states it'd make a few more horses too

 

True storey they are big but not as heavy as the old ones cant wait to see what your car will do when you get the 3.5 tail gears

 

Some long overdue updates...

Ran a personal best tonight, twice.



Better run was 12.935 @ 107.21mph, with a 1.929 60ft

I've pretty much acheived my goal of running a 12-something in this car.

And if i'm not mistaken, this is the quickest X350 XJR without nitrous or a twinscrew... ?

 

Interesting thread!

Do I understand that you have installed a (Quaife?) LSD diff in your car? Was it much of a project?

I have an '07 XJR here in the states. Just in normal driving - particularly in the rain - it is very prone to spin the inside rear wheel.

I have had other powerful sedans over the years (E55, S8, E63, several M5's, and a current M3 coupe), and all had LSD, IRRC.

Did any (x350/358) XJR's come with it? Seems lack of it (in my '07) was an oversight

Compliments on your methodical approach to making power mods. Did you confirm that the airbox flap solenoid was actually bad? Assume that if it did actually open the flap at WOT there would be little to gain in disabling it?

Other than the airbox flap, is there anything else you would suggest for a daily driver XJR? My car has about 100K miles, and I've performed the normal maintenance items (but no mods)

 

Well done! That's the quickest X350 XJR I've certainly seen without TS/NOS. It seems your trap speeds are very similar to the runs earlier in the thread from 2013 (106/107mph) but you've taken a nice dent off of your 60ft. Did you change wheels/diff?

 

I believe Cambo does have a Quaife installed and he pointed me to a UK supplier where I purchased my Quaife recently.

I used this thread https://www.jaguarforums.com/forum/x...lation-155867/

to install it in my 2005 XJR a couple of weeks ago.

It was fairly straightforward although I was sidetracked by installing new rear bushings.

 

This thread got me curious in how quickly my car would complete the quarter mile, or rather how fast it would do so as my car is impossible to launch hard from a dig. So in the interest of science, and my own fun, I did a little testing tonight on some private land before the car goes in on Monday to have the supercharger swapped back to the Eaton.

I was mostly interested in the trap speed as I knew traction would prevent me from putting down a good time on an unprepared surface with the open diff and summer tyres. I was hoping for over 110mph, having seen modded STRs/XJRs trap around 108mph with similar mods to what I used to have when my car was much slower. Unfortunately I don't have an expensive Racelogic V-box, so I relied on Torque Pro. I did two separate runs on the same road back to back:

1st run: 13.421 @ 116.2mph (1/8 mile was 9.418 at 95.1mph)
2nd run: 13.348 @ 117.4mph (1/8 mile was 9.253 @ 95.1mph)

Incidentally, I also saw 432 g/s peak MAF rating tonight which is very near what I have always seen using the current pulley. I've also recorded a 60-130mph time of 9.5 seconds consistently which is MUCH faster than with the same mods on the Eaton with a 1.5lb pulley. Launching the car is however impossible currently as TC immediately bogs it down before it regains grip and shoots off.

My mods are:
1.7 Autorotor supercharger with 2.5" upper pulley and stock lower
3.5" intake pipe with K&N panel filter
Mina backboxes

Fuel: 99RON V-power and full weight (including a stock Eaton in the boot!)
Temperature: 10 degrees celsius

I was initially very cynical of the trap speed, until I repeated a very close result. Then I put on a separate sensor for just the GPS Speed and monitored it as I drove around, it was more or less consistent with my speedometer give or take a mph which made me believe the speed is accurate. I was expecting ~112mph for trap speed, but the 117mph recorded is XFR territory. I have however driven an XFR hard and I did not feel any more power over my TS STR which again leads me to believe the trap speed is accurate.

Has anyone else used Torque Pro's quarter mile function? Is the speed over-optimistic? I'm wondering how accurate it is and would love to use a Racelogic box for further testing if someone wants to lend me one!

 

Yes I have a Quaife in this car. It is by far the BEST money I spent on the car and totally transformed the way it drives.

No X350's came with LSD, they are all open diffs.

Yes the solenoid in the airbox was dead/jammed up.

Actually the way the flap normally works, it doesn't open until you have quite some rpm and engine load. Taking the flap out does give you a bit more oomph in the lower rpms. One side-effect is you can hear the supercharger come on boost (starts to whine) at lower rpms and throttle position. For this reason alone I would recommend it

I am working on a "list" of things to do to get the most out of your XJR or STR, we've all learnt a lot over the last few years, it'll be good to put it all in one place.

Same diff, wheels, tyres, no changes there.

The only recent changes have been sparkplugs, and the tune.

There is one last thing that we need to test/try, and based on some hard work from Datsports, I think this will make all the difference and really get the most out of the tune.

Watch this space!

Ha!

With those times vs. traps you obviously have no traction at all...

If I had the power for 117mph trap i'd be doing high 11's LOL

You are onto something with the MAF rates though, this is where mine is not "right" and hopefully we will have this fixed next week.

Thread on MAF rates here ==>> https://www.jaguarforums.com/forum/x...-382-a-175551/

 

Welcome to 12sec club

 

For what it's worth, I did get a couple of runs in with 108mph traps.

108.06 and 108.11

But with traction issues on those runs the quickest ET is still 12.935