I read that that my 2011 Jaguar XJL 5.0 Liter, naturally aspirated (non-supercharged) saloon is factory limited to a speed of only 121 mph, but is probably capable of 178 mph. My new Continental tires on this car are speed rated to 186 mph. Are their any "tuners" near me (North Carolina, USA) that could allow my car to "do it's thing" on a race track, closed course or Autobahn?

 

Tuning the 5.0 SC engine can get you serious power increases. The normally aspirated 5.0, I am not sure that significant changes can be achieved. ECU Tuning Group has the best reputation in the forum for supercharged vehicles. They sell a tune for the 5.0 NA. They can send a laptop and you can reprogram it yourself.


ECU Tuning Group

 

Thanks Ed - I'm really not looking to increase engine power, which might have other negative effects, but simply to remove the 121 MPH electronic speed limiter programmed into the USA 5.0L NA engine XJ (X351). Back in '57 I drove a 300 SL Gullwing Coupe up to 135 MPH before I noticed how fast I was going (had one eye on the tach, one on the road), so some '57 years later I would like to be able to exceed 121 MPH (legally) if I so desire. p.s. back in '57 the legal speed limit was "reasonable and proper" where I lived, which 135 MPH was for the conditions and car.

 

It seems they have a excellent reputation with forum members. I believe part of their program removes those limiters, smooths shift points and can actually improves performance and mileage.

 

Thanks,
I e-mailed the EUC Tuning Group here in Apex, NC, about 131 miles and 2 hours 40 minutes away, requesting a quote to simply remove the factory imposed speed limits from my '11 XJL 5.0L N/A Jaguar. I told them I would verify that their "tune" accomplished this simple goal, and that I wasn't interested in increasing torque or horsepower. I shall share their response and subsequent performance with everyone. Seems like a simple and easily verifiable task that will verify if "tuners" are simply con artists preying upon gullible car owners, or if they can actually deliver measurable results. Stay "tuned".

 

Talked with Danny at ECU Tuning Group, in Apex, NC, and while they know how to change the setting on the engine control unit (ECU), they believe their is also a limit set on the transmission control unit (TCU) that they presently don't know how to change the settings on. So, far the present, it looks like I'm stuck with a factory limit of only 121 mph even though my much less expensive Corvette can do 190 mph if required to do so (I love telling my wife as we cruise along at 63 mph "just think, dear, this car can go three times this speed".