XJ8 top speed
 

Greetings. I'm sure this has been discussed but I haven't found a definitive answer. Top speed of US and Canadian 2004+ XJ8 is limited to 121. Quite disappointing given the cars potential. Curiously, I saw that the new 2011 base XJ is also limited to 121. Assuming properly rated tires, I'd like to be able to override the limiter. Plenty of programmers available for other vehicles, and in fact have successfully used a Superchips Flashpaq on my F150 to change this parameter(I know, I know...not the same thing). However, I haven't found anything of a similar ilk for the Jag. Anyone gone down this road with any success? Thanks in advance.

Sorry, posted to wrong area
 

Sorry. I just realized I should have posted this in the 2004-newer section.

Well, unless I am sadly mistaken and my eyes crossed, I do believe I had mine well over 120mph just a cpl weeks ago.

I am quite confident I have read that the car is limited at 155mph but I won't swear to this, nor do I ever intend to find out if it will make it, lol.

My 06 is limited to 129.. reason is simple, the US-Spec cars come from the factory with H speed rated tires. Reason is, if Americans need to replace the rubber on their $65K+ car in less than 20k miles they go bananas...

Idrovemy 04 xjr cross country, in montana where the speed limit is 75 but really I was averaging 110 90% of the time, I got my car up to around 137 mark. quite exhilarating...

You guys need to try riding motorbikes for some real thrills! ;)

Ya, did 90 MPH on my 01 Shadow. That was fast enough in the open wind for me. I do believe the earlier x350 are limited to 155 MPH.

The 2011 XJ Supercharged top speed is limited to 155--it has ZR rated tires.

I have a 2005 Jaguar XJ8L model with the 4.2L engine that I purchased in January 2014. It was originally a Florida vehicle, and it came with Pirelli P235/50 ZR18 97W tires. Does anyone else know what the top speed would be for that vehicle in the United States?

Well, I did take my 2005 Jaguar XJ8L on a trip along the expressway to Indiana last May to pick up some specialized fireworks. I didn't set the transmission in Sport Mode at the time, but I did clock 110 MPH briefly on the way there. Unfortunately, I had to take my foot off the accelerator at that point because of approaching traffic up ahead.

My hands were a little greasy at the wheel too so I'm not sure if I would have dared to open up the throttle much more anyway. What I can tell you is that 110 MPH is fast enough for anyone.

Has anyone else taken their Jaguar XJ8s (with the standard 294 HP engine) out for a spin? I'm just curious as to what the top speed of that vehicle is (in the United States).

I have an 05/XJ8L and no where do I see where it is limited to 121 MPH. It says in the book that it is electronically limited to 155. If your using the speed limiter to try to get above 121, I haven't even thought about that but, the limiter it's self may have a top speed of 121. I believe if you forget about the limiter and just go out and punch it, I think your hands will be a little greasy too. Mine were as the speed-O passed the 130 tick, so I backed off too. The car just sat there as the air suspension lowered it down to the road as designed. An important feature one looses when he switches to plain old springs.
121? Never heard of such a thing.

Interesting point about lower speed rated tyres (tires,sorry) I know that my old 308 is limited to 249 KPH and because of that the tires needed to be 300 KPH rated to appease the road registering folk,should they check.

To lower the limited speed because the factory fitted lower speed rated tires should be easy to bypass for the right person. It also points to some-one got cheap seeing little 4 cylinders stuff achieving 120mph.

X350 for North America is limited to 121 MPH for all naturally aspirated vehicles. This is well documented. All supercharged vehicles (Super V8, XJR, and 06 Portfolio) are limited to 155 MPH worldwide. Anyone saying otherwise has either a modified vehicle or is misinformed. This information is readily available. In fact here is an exerpt from Jaguars press release for the then new X350:

JAGUAR INTRODUCES ALL-NEW 2004 XJ RANGE FOR 2004

Embargo release date: 21st December 2002 00:01:00

This Press release has to be one of the longest Jaguar has ever put out! Here it is in its entirety. Note that this is a USA originated document and that some details may not apply to other markets such as the UK.

"The new XJ is both quicker and more economical across the board than the outgoing generation – and many of its competitors. As an example, the quickest model in the new XJ range, the XJR, dispatches the 0-60 mph sprint in just 5.0 seconds and has a top speed electronically limited to 155 mph. The XJ8 records 6.3 seconds 0-60 mph and has a top speed electronically limited to 121 mph."

http://www.jag-lovers.org/x350spec2112.php

So for anyone who wants to argue the point, this is an official Jaguar Cars Ltd. document. I find anything else on the internet subject to interpretation, including Wikipedia and various non-instrumented reviews.

PS. I have had my 06 XJ8L up right at the limiter several times. There is no fuel cut off as in rev limited japanese cars. The engine was turning around 3400 rpms ( I beleive I was in 5th gear, but have no way to know for certain.) My hands were quite steady and dry and the car was planted, stable and quite comfortable at that speed. I believe as long as the road allowed, it would happily have run at that rate all day long. I felt no need to "back off" at all except for knowing my luck to have the road to myself for much longer was limited as well. The only noticeable sensation other than speed was some wind noise around the sunroof. I doubt I would be able to ride at the XJR's limited 155 mph for more than a very brief time. I am not THAT crazy.

top speed
 

Yes that is correct Blaireware, thanks....

It did seem to me that I may had been approaching the limiter when I briefly reached 110 MPH on the way to Indiana, but I did not have the transmission in 'Sport Mode' (if that means anything in this case) at the time.

What I do know is that the vehicle had Pirelli "W" rated tyres when I acquired it last March, and those are good for up to 150 MPH.

With the coil/spring suspension that I have on the vehicle, will that tend to make the front end 'light' at speeds above 110 MPH?

RICKKK
Since you do not have the air ride suspension, I would say yes. The car as it came had air suspension and that has the feature of lowering the car at higher speeds. This causes less wind interference, helping the car "hug" the road. With just coil springs, it doesn't have that feature , thus allowing wind to better get under the car, thus lighter front end. Lower speeds are your best safety bet.

Thanks for the info. My XJ8L is plenty fast for me, especially in Sport Mode.

What's the idea of putting speed limiters in the Jags sold in the United States to begin with? I wouldn't imagine that it would be in Jaguar's interest to do so. Is this federal law?

If the limiter was removed from my 2005 XJ8L, I wonder what the top speed that the 4.2L would be capable of delivering.

I keep reading comments made by forum members about the [Sport Mode]. Some must think that if they have selected the Sport Mode, it has an affect on car speed---that is, the car will go faster if in the Sport Mode.
The Sport Mode does basically one thing: If the driver selects the sport mode, what ever gear he is in--left or right side of the "J" gate--from a stop, the longer he holds his foot down the longer the transmission will stay in (left side of J gate) 2nd, then third, then fourth, then 5th gear. IE; If he has the shift lever in 4th gear and mashes the gas pedal, the transmission will not shift up to fifth until either the driver backs off on the gas, or the engine reaches an RPM it deems necessary to up shift. Same reaction if on the right side of the J gate, except here from a stop the transmission starts in 1st gear. With the selector in the drive slot (D), from a stop it will go from 1st to 5th. When he lets up on the gas then it will go into 6th--if your car has a 6 speed. Nothing else! It won't make the car go any faster at top speed. The Sport Mode will just allow the driver to possibly get to that top speed (what ever he thinks his car is limited to) somewhat faster, depending on how hard he wants the engine to work. IE; How high he wants that engine RPM to get.

From what I could gather, the speed limiter for the 6-speed XJ8's can easily be overridden by simply staying in 'Sport Mode', and J-gating in 5th. Apparently, as soon as the engine has reached a certain RPM in 5th, the vehicle will automatically switch over to 6th. At that point, a few more mph will be attained.