There's a couple of XKR's in Germany that have the tune from my guy in them, no pulley, just tune & exhaust. Both have the XKR-S exhaust on them (this is a must) but unfortunately no before & after dynos from these cars, only an after dyno from one of them, and it was one of those ones where the power at the crank was estimated, 596PS was the number it came up with, but without a before run that's a bit contentious, take it with a grain of salt.

What they like to do in Germany is 100kmh to 200kmh runs with a V-Box, and the results from those were;

Stock XKR tune, stock XKR exhaust, 9.8s, 100-200
XKR-S tune and exhaust, 8.6s, 100-200
Modified XKR-S tune and XKR-S exhaust, 8.2s, 100-200

Which is pretty good, so i'm told...

 

Sounds like a useful increase in power!

Assuming you are talking about replacing the resonator with an X-pipe, do you know if something like you just had fabricated for your car would work or does it need to be the real deal?

 

The guys in Germany got original XKR-S exhausts 2nd hand, off eBay LOL
Seems that some XKR-S owners got aftermarket exhausts and sold off the originals.
They got them very cheap too... but new ones are damn expensive and actually restricted for sale now, you need to provide a VIN to order one as a spare.

If you got a "replica" of the centre section made, it would do the same job.

The rear muffler assembly on the XKR-S is different to the XKR too, the external pipes to the tips are bigger and there's some different piping inside them too (one of the German guys put a borescope down the XKR and XKR-S mufflers to see).

I don't think there is much if any of a power gain from the rear muffler, it's the centre section that makes the difference.

 

I've asked before and didn't get much of an answer. Is there a HP difference from the PAE X pipe vs the resonators. If so what would it be and why isn't is listed in the factory spec's. Just curious

 

Back to the 4.2 XKR, I ran this tonight

 

Looking good. Your terminal speed is faster than my best and your standing quarter is obviously much better!

I had the Magnaflow cats fitted yesterday and put the factory resonators back on and it is too loud to run with the fuse out now. Luckily the mods I got you to do to my tune keeps the valves closed above 1000 RPM so it is fine like that.

If I was keeping the car I would probably get you to raise the valve closing point slightly so that it burbles around town and is still quiet under acceleration but I will leave that to the next owner to sort out.

 

Finally got a chance to get my stock '2010 XKR to the track this weekend.

The OEM Dunlop Sport Maxx's were a limiting factor but I did a best time of 12.533@115.41 and my best terminal speed was 115.73.

Time to start some upgrades

2012 6.2 litre Mercedes AMG C63 Wagon 0-62 4.6 secs v 2010 5.0 litre Jaguar XKR 0-62 4.8 secs

Final Results

Jag - 12.533@115.41
Merc - 12.998@108.01

 

Good to see another xkr belting down the dragstrip 😀

Impressive reaction time as well..looks like you've done this a few times before !

 

Thanks. It is only my 4th time but I was told to go when you see the second yellow and that seems to work pretty well.

I did get a red light on one run yesterday and I still had my foot on the brake! I put both stage lights on simultaneously though when lining up so I may have overshot the line by a hairs width.

 

Awesome effort

Every time cambo and myself head out to the drags we get a far bit of attention I guess it's not everyday you see a jag there

Keep it up can't wait to see the mods and how it performs

 

People are surprised about how quick the XKR is, especially the 5 litre.

Out of interest do you guys do a burnout before your run or just line up and go?

 

The xkr 5L is an absolute rocket ship guess the hardest part is trying to get it off the line !

A quick burnout to dust off the tyres lol.. will try and dig up some pics

 

With treaded street tires, no. They just tend to get slipperier. On the last yellow, whack the throttle to load the suspension, then back off a lot before the tires break free. Then roll onto it as hard as the tires will allow.

Write 'no water' on your windshield and just rap the throttle hard enough to spin the residual wetness from the water box off the treads before staging shallow. You just want the front tire to barely break the first beam. That gives you a little free acceleration before breaking the 2nd light and starting the clocks.

 

I always do a burnout, I've tried launches with cold tyres (drive around the water) and the traction was always much worse.

I've got Michelin PS4S on the XKR, they are great tyres, but still need to be warmed up.

Don't load up the power on the brakes, there is a torque limiter which reduces power if you stall it up. The fastest launches are just punching it from idle, it's slower if you try loading it up.

The 2.10 and 2.18 60ft's are a bit slow, I consistenty get 1.9's from my XKR. That stock 5.0L convertible on youtube that did a 12.2 supposedly did a 1.8 60ft.

 

Two slightly differing views but thanks for the response guys. My worst run last outing was actually the first one where I did a short burn out then just punched it off the line. I did a 13.88 because I had to back off to wait for the wheels to stop spinning so I may have been a bit over enthusiastic on the throttle.

My next run was 12.892 and for that one I did no burn out then just eased the throttle off the line and the times got progressively better from there using the same technique. That does mean that my 60 times are a little slow though.

A lot of the guys on street tyres do seem to do big burnouts though so I will have to do some more experimenting.

At the last meet, the first few runs I tried were in sports mode and felt that the power was backed off a lot more between gear changes when compared to just D with Dynamic mode selected. That may be because Sports mode allows it to rev higher but I stuck with D after that.

I also wondered if turning off Dynamic mode might allow the car to squat more which might help with the rear end grip. The down side is the change in throttle response and driving dynamics.

Unfortunately they only seem to do race days at our track so you need to use the 3 or 4 practice runs you get in the morning to nail down a sensible time to dial in for the afternoons competition.


The next meet isn't until April so I will hopefully get a chance to make a few upgrades before then. Unfortunately the tyres look almost new so I don't think that will be one of the things that will get changed as they aren't cheap here!

 

I felt a bit ill when I handed over the money for the Michelin PS4S' I'd never spent so much on tyres in my life, $640 AUD each for the 295's at the time, they seem to be a bit cheaper now though, but they were worth it, amazing tyres.

Until you get your traction sorted, adding more power will only make things worse.

 

The upgrades have started

Before making the mods though I did a base line dyno run (see attached).

Thanks to Cambo my '10 XKR now has a genuine XKR-S X-pipe on it in place of the mid pipe resonators. I had thought it would be louder but it has changed pitch more than volume. It is a bit raspy when cold but once warmed up there is a real howl to it, much different to my old 4.2L litre.

As it was too hot to do gardening today I had a play with SDD and applied the XKR-S PCM tune to my car. On paper there is around 40bhp difference between the XKR and XKR-S and I was surprised what a difference it makes. The car feels so much more lively and the mid range acceleration is noticeably improved so I will hopefully get another dyno run done in the next week or so to see what difference there really is.

I am also waiting for my mechanic to sort out a warranty claim on my supercharger because the torsion coupler needs to be changed and while that is being sorted I will get the pulley changed for a smaller pulley. Once that is done I will hopefully do another dyno run.

Once that is all done I am planning to apply the tune from Old Jaguar (Cambo) and do a final dyno run. The final result will hopefully be somewhere between 550 and 600bhp.

 

Wow, what a disappointing A/F curve starting at 4k.

 

The curve might be exaggerated by the fact that the bottom unit on the graph is 11.

The A/F graph on my 4.2L dropped to just over 10 at higher revs after being tuned.

 

Just over 10 afr is where standard non tuned 4.2 supercharged are at from factory