Originally Posted by jahummer (Post 2318794)

You're referring to the 5 litre XJ, not the 4.2 XKR, right?

Originally Posted by rkosinski1 (Post 2318795)

Hi
I posted about the RICA tune on my 2013 XKR
I bought the car new and it took them 3 tries to get the software right.
The first download was horrible - the throttle tip in was virtually impossible to control and unusable - the "jerking" problem people are referring to.
The second download solved the throttle tip in problem but basically unmasked a problem with the E-Diff.
I've been running the third download for 7 years with no problems. The whole process took about 6-8 weeks as I recall.

It should go without saying that the Stage 2 version includes a smaller pulley to increase the supercharger boost, and the ECU map requires that.

The whole point of my statement about the 50-100mph time was that, as others have noted, the car doesn't have launch control and obviously isn't AWD, so when you shut the traction control ALL the way off, you just can't use the horsepower from a standing start - you have to be going 40-50 mph for there to be enough grip without any wheelspin to hook up under full throttle. I haven't done a run with an electronic timer, but stopwatch timer showed sub-5 seconds 50-100mph when I posted my comment..

I'm curious now to see what an electronic timer will show and will try it next year (car is already off the road for the winter here in New England) . Frankly though, it scares me to push the car over 100. I find that when accelerating under full throttle through 110 the front end starts feeling very light, and it would be very easy to lose control. Not sure if true, but a UK Jag engineer told me that the hood vents on the XKR are designed to relieve underhood pressure for this reason.

I don't profess to be any kind of expert here, just relating my experience..

Originally Posted by jahummer (Post 2318275)

There is another known tuner in Europe who recently posted up dyno sheets showing 700BHP/850Nm TQ with a tune on the 5 litre.

Originally Posted by jahummer (Post 2318811)

Read this thread very carefully...

Originally Posted by Cee Jay (Post 2318852)

Anyone in the world can get a stock XKR-S tune, as long as they have the Resonator Delete + X-pipe, along with access to SDD. That wouldn't help those who already OWN an XKR-S though.

Originally Posted by StiggyMac (Post 2318863)

If that's the case, why aren't there more XKRs rolling around with the XKR-S tune if all it takes is some plumbing and software? I'd like to know because the the sample size of XKR-S owners is very small, with little to no knowledge of where the limitations are that those power levels.
I'm trying to sort through the keyboard owners vs. actual owners with real world execution of these tunes, so I can make some informed decisions about how to go about pushing the power envelope.
With so many people with the 5.0L SC motor I was hoping more people would be able to provide some real data rather than all the hearsay.

Anyway, back to researching and sorting fact from fiction.

Originally Posted by tmich (Post 2318649)

To be precise- he said "about 4 sec" (50-100mph).

@Alex
0-60mph in XFR <4sec - never driven one of them, so don't know their traction, but it is hard to believe that it goes faster than XKR, and I have never seen <4 for XKR. Not due to power, IMO due to traction and RWD.

In general question is about a measuring tool. I use app with an external GPS antenna (10mhz) so it is rather precise (~300usd set), but still it makes error (e.g. have records like 0-100kmh below 3 sec which is b/s). I'm only convinced with repetitive results, not one offs.

Originally Posted by tmich (Post 2318926)

1/4 mile in ~12 seems absolutely realistic, but 0-60mph <4sec is IMO possible only with a strong back wind.

But look - I'm not offensive, rather jealous ;)

Originally Posted by AlexJag (Post 2318930)

Thats what it does, faster than a stock XKR-S and faster than my record on my 4.2 Xkr of 4.05. Keep in mind that with1 ft rollout as magazines test ( look in lower left corner on screenshot) time is 3.75 0-60
Can do an ECU tune on yours as well

Originally Posted by rkosinski1 (Post 2318948)

Yes, but if I'm not mistaken the XFR/S has some form of launch control, correct? That is missing from the XKR/S

Originally Posted by rkosinski1 (Post 2318948)

Yes, but if I'm not mistaken the XFR/S has some form of launch control, correct? That is missing from the XKR/S