Does anyone have any info on the governing chip in a 2010 XKR. I've heard that it can be removed and you make a crazy jump in horses. Is it true or just an urban legend?

 

It's not even an urban legend, just untrue.

 

I believe what you would be referring to is tuning the ECM. Look into some of the ECM tuning threads for more info.
The mph limiter and performance can be adjusted via tuning the ECM.

 

You can definitely get the speed limiter increased or removed (Viezu will do it, for example). But you need a full ECM tune to increase power/torque. However, the extra grunt will put strain on the transmission (the 550 HP R-S has an uprated torque converter), and you really need the Speed Pack bodykit for high-speed stability.

 

After testing my 2007 4.2 XKR several times it limits at 270 kph (~167 mph) on the speedo. I gonna have some more tests with GPS measuring to see how fast it actually goes. Looks like the previous owner (I'm the second) had the limiter increased.

I can confirm that XKR tends to get a bit lighter at the front at 250+ kph but its nothing to worry about a lot. At 260~270 its still pretty good to control despite the slightly light front.

 

With the Speed Pack, you get 25% more downforce, and the car is rock solid at 300.

 

I can confirm, speed pack makes the 2010 stable, I've had mine to clocked 302kph on a runway.

 

Apparently not. I just checked the parts catalogue (Oct 2013) and there is only one part number for 5.0L S/C torque converter. Same regardless of 510hp or 550hp. There is a difference for S/C and N/A, but that's normal.

BTW, you can bypass the speed limiter.

On the 4.2L have the shifter over to the left in S mode, and if there is another mode to select "dynamic" or sport or whatever, make sure it's selected.

When we were back in Switzerland & Germany my 4.2L XJR sailed right through the limiter on several occasions to an indicated 170mph / 270kmh, had to have the gear lever in 5th i.e. not D, and sport mode selected. I did get the limiter at 255kmh (indicated 260kmh) when the shifter was left in D. Many other people have reported the same with XKR's and XF's.

 

When the 75 was released, part of the spec was "Upgraded torque converter to handle the increased torque"; when I interviewed one of the developers, he said that this was "carried over to the R-S".

It's possible that they simply changed the torque converter for all R models at some point, or that the part was generally improved without changing the part number. It would be interesting to see if the part number was different in a 2010 catalogue.

Or it may have just been PR BS...

 

On the speed limiter: yes, the general consensus seems to be that it only operates when you're in 6th gear, so keeping the car in 5th means you're only limited by rpm.

So, on the 5.0, 'S' mode (to keep it in manual), manual shift, and Dynamic Mode (for increased stability). Mine doesn't change up to 6th in 'S' auto until 177 mph (285 kph) on GPS at 6250 rpm, so you should be able to get to that with a normal 5.0 XKR.

 

Mine was in regular D mode when going the 270 kph O_o

 

Yeah, but (as discussed on the other thread) yours may have been de-restricted. Which is not unusual in Germany

 

Yep, I gonna have a performance shop next to my place whos specialized on british cars have a look into the ECU. Ill keep you informed.

 

Hmmmm, speed pack. Is this the raised rear spoiler and the deeper front splitter? I find that around 140 the front starts getting light on my stock 2010 XKR.

 

Yeah, bigger rear 'flip' (not a separate wing like the R-S), rear diffuser, front splitter and side sill extensions. Mine also has the equivalent of the Dynamic Pack, so it's 10mm lower too.

 

Thank you. By the power of google I've found some pics etc.

Think I'll save the pennies for tyres.... Will be needing another set soon