This is a question for all those that either know or have done it before - will a stock power XKR be capable of 300kmh if the limiter is removed? If not, how much extra power is necessary?

Reason for asking is in NZ we have an annual LandSpeed Trial event in Reporoa where it is officially timed and your speed measured. Many cars of this generation have hit close to this speed so figured I'd ask to see what's needed. I'm planning on joining this next year. I have correctly speed rated tyres and will upgrade pads/rotors to handle the power needed.

 

I've had mine up past 177 mph / 285 kph and it was still climbing slowly, but there was a reason I had to discontinue at that point. The elevation in that area is pretty high, so I'm sure the lack of oxygen didn't help performance. Oh, and that was with an XKR/S tune. The 15% power loss due to altitude would more than cover that difference though. I do think I could have gotten pretty close to the 300 kph limit in another minute or so.

 

Thanks. Any concern with the front end lifting around those speeds? I'm in the early process of making an XKRS-GT style louvered bonnet which should help with heat and also reduce lift a bit.

 

Not that was apparent, but my undertray (belly pan) is intact. I think maybe some people who state the concern may not have that tray.

 

The Speed pack aero kit apparently improves high-speed stability significantly and would be a "cheap" upgrade is you don't have it already. Had mine up to 274 kph on the GPS and it was "no sweat" at least from the stability point of view! Was still pulling quite well but the bonnet wasn't down properly on one side so had to give in at that point!!! They say even the base 5.0 has enough power for 300 kph plus but not really the stability to do it safely - they are too softly sprung, more for decent everyday use.

 

A front splitter helps more than you'd think for front end stability. It cuts off air that wants to get under the front, thereby keeping it more stable.

 

as does the hood openings preventing excessive pressure to build and slightly lift the front end
wj

 

I've got the speed pack spoiler now and will probably get the mina gallery replica of the front lips are it's significantly cheaper. Also toying with the idea of an upper pulley and tune. I'm sure 560+ Hp would be more than enough to get the job done.

 

Funny (not) thing for me; I got the XKR-S tune and the speed limiter reset specifically to do the Silver State Classic again when NOT categorized with the Hondas and crap like that once more at 130-155 mph (demoralizing). Then before it happened, COVID 19 hit and I didn't go again regardless.