Hi! I have a Jaguar XK 4.2 coupe 2007 and it's obviously limited to 155mph (250km/h)
I'm a bit curious to know what the top speed would be without the speed limiter. Do any one of you have the car without the limiter and is it a pain in the *** to disable?

 

Were you in sport mode?

 

German Jag forum has a thread on this, someone mentioned 270km/h for a 298PS 4.2, so naturally-aspirated.

There's also this thing by Arden, which probably plugged into the ECU or something.

 

I've felt mine come loose at 150 cresting a shallow rise on the interstate so I'm sure you'll fly if you go much faster straight and level. The faster limited cars all have better aero features, higher spoilers for the speed pack cars and wing for the XKRS-GT plus other bits.

The 4.2 XKR accelerates so fast you can easily get into trouble on a normal 2 lane road with the limited aero we do get.

 

The front felt light on my XK above 120 mph if memory serves...

 

I think Jeremy Clarkson specifically mentioned that the front does start feeling light around 120mph, and blamed the small rear spoiler for it.

 

The front of my XKR felt rock solid all the way up to the limiter. On a track, of course... Maybe it has a different undertray/ front diffuser than the XK?

 

I recall reading the figure of 178 mph (286 kph) achieved by Jaguar in development testing with an unrestricted 4.2 at Nardo in Italy.

Graham

 

Jeremy Clarkson, on the XKR vs V8 Vantage Top Gear video said that their XKR got up to 175.

 

Yes, and it was also smoking both rear tires. Somebody got a hopped up version to play with...

 

It may have been the 5.0 S/C version, and my memory IS pretty lousy these days, but wasn't an XFR tested with no limiter and a few added Aero Accouterments and it got up to 225mph? It'd be FUN to add a Speed Pack, remove the limiter and go whuppin' some 911s.

 

I was at about 125 and I felt like the rear was moving a little.. I haven't gone over 100 since.. too scared.. Also that was my first day owning the car and on my way back to Iowa from Miami.. everyone else was doing 100+ on the highway outside Miami.. so I felt that was a good time to test it.. lol Mines an 07 4.2

 

With a modified car, on a track I have maintained continuous speeds of 120-130 with perfect handling but going over 160mph the front end did lighten up, I have since made additional significant changes to aero, steering and suspension but have not had time to take it out again. Would love to push it past 175mph.

 

And how can one remove that limiter? Is that a fuse to remove?

 

No. That requires special surgery and a hacked version of SDD, and nobody will let you do that.
Besides, the 4.2 can't get much over 155 anyway. heh heh heh.........

On a side note, I was pre-registered for the Silver State Classic last year in the 170 mph class, but dangit for C-19 and the notorious year of 2020.

 

Hit the limiter in my 2008 XKR Portfolio, it's well above 155mph 😝 But car felt nice and planted all the way up thru 150mph....on a smooth freshy paved surface....somewhere in Mexico 😁

When I hit limiter (fuel cutout?? At least that what it felt like) I was really concentrating, but glanced down to see 174-175 ish indicated.

Alternatively I had a 94 Firebird Formula (limiter removed) that fairly easily pegged the 155MPH Trans Am cluster I retrofitted, but was quite a bit more...unsettling. Car rode like a sled and hopped and skipped around a might. I let off at 155MPH indicated.

Disclaimer: I am an idiot and crazy top speed blasts down in Mexico should never be attempted by anyone.

 

I thought with stock suspension my 08 Xkr convertible felt floaty past 120mph. With the addition of stiffer springs now feels much better. Limiter can be changed either in SDD or with performance tune , I can do either for those interested...

 

Can you actually remove the limiter or just set it to one of the higher options?

 

Using SDD you can only increase, as you have shown.
I'm sure there's a different method, but I don't know that one. Wish I did, although 185 is kinda high as it is.

 

I thought the XK had stiff spring with softer dampers, a pretty unusual suspension set up? The bump steer on the XK was quite pronounced.