Does my '07 Super V8 have a speed "governor"? I am "now" aware of the ASL function, but I am wondering if there is an absolute speed limiter.

This morning, I had to pick up the kids from camp near the Arkansas border, so I had a nice 90 mile drive each way. The roads were good and the traffic was light, so I decided to run it out a bit and see what it would do. I got up to about 120-125 mph and that was it. After asking my wife to read the manual, I tried disengaging the ASL on the way back, but same thing, same speed.

I could have sworn I got up to about 140 mph in my father-in-laws XJR, so is it my ASL that is limiting the top speed or is there a "governor".

Sorry for the "stupid" question and I did consult the manual after I got home. It wasn't quite clear to me from the manual and with the ASL disengaged, I figured the car would have gone faster. Thanks in advance.

 

For US vehicles, 121mph. Be a "Sport" instead...if you get my drift.

 

Well, that sucks *****! 121 mph, really? My wife's Mercedes-Benz Wagon will do that, and it is a normally aspirated V6 "lead sled"!

Thanks for the reply Box, but I don't get your "drift". I always drive in 'Sport' mode, so what am I missing?

I swear my father-in-law's XJR (maybe a '03-04?) went faster. What gives? Maybe I was "hallucinating"?

Seriously, no one really "needs" to go faster than 121 mph, but........

Is there any way to disable the limiter without "mucking" things up electronically? Just curious.

My old BMW M3 was limited to 135-138, and I thought that was "weak"! I figure a Super V8 ought to be good for at least 140-145 mph, especially since it pulls so hard above 100 mph.

Thoughts? Thanks in advance.

Regards,

Jim, III

 

Be a "Sport" and pull that little J to "5"

 

Thanks Box! Got it! Thanks for the "tip"!

So freaking "American"! With top gear an "overdrive" for CAFE standards and fuel economy in most domestic cars, you actually go faster top end in a lower gear.

Question: do you max out in 5th gear or does it automatically upshift to 6th gear past 121 mph in the J-Gate mode?

At least the Germans set their limiters in the 150-155 mph range. 121 mph just seems very "light" for a car of this caliber.

Can you override the limiter? Just "curious".......

Regards,

Jim, III

 

As I understand it, and as is explained concerning my `04 is that H rated Conti's originally fitted left it limited to 121.

 

The XJRs are speed limited to 155 mph, but I think the rest of the line has 121 speed limiters.

 

Thanks Box and Carelm.

Man, I am disappointed! It may well be for the best with my penchant for speed, but what a waste! I so love my Super V8, but I would have bought a XJR had I known there was a 30+ mph difference. Hell, my diesel Dually will do 110 mph! I get the "safety" aspect, but then again, we don't even have helmet laws in Oklahoma.

In short, is there anyway to "chip" the car or overide the speed limiter? I took my father-in-law's XJR to 140+ mph on a good road with no traffic, and it was smooth as silk. Very stable. I doubt I will have much need to go that fast often if ever, but my car feels "neutered". I am really disappointed!

Sorry to bitch, but any suggestions to overide the limiter? Thanks in advance.

Regards,

Jim, III

 

Here at JaguarForums we do not condone dangerous/reckless driving, street racing or breaking of traffic laws. So this thread will be closed.

The topic of the speed limiter has been raised many times before, a little searching on the forum would have answered your questions.

Before I lock it up, let me give you the technical answers.

Your vehicle may be limited to 121mph because of the speed rating of the tires fitted at the factory. This was the case for the regular XJ8 and other "non performance" models.

I am surprised if a Super V8 would be limited to 121mph instead of the XJR's 155mph, since the driveline is the same. If it is, it's because of the tires. Check the speed rating of your tires (assuming any replacement tires fitted were of the exact same specification)

It is well known that if you move the J-gate out of D (into 4th or 5th) and select sport mode, the limiter is bypassed. The gearing of these cars means redline in 4th is around 155mph anyhow.

Changing or even removing the programmed limiter is possible, either through aftermarket tuning (though not always possible/feasible, not many tuners can do this) or by modifying the vehicle settings with the dealer-level diagnostic system, also known as IDS or SDD. But a Jaguar dealer will very likely refuse to do this for you.

Thread closed. Thanks for your understanding.