I checked my 0-60 time the other day, and while it felt pretty fast to me, it doesn't seem that great when compared to some of the numbers I see in magazines. The "Torque" program on my Android phone varied from 6.0 seconds to 6.9 seconds on several different runs. I wonder if the program can actually measure the times accurately. It gave me some really screwy numbers for my 1/4 mile time (like 8 seconds or something). Maybe I should try measuring everything manually.

 

How does that program measure acceleration? By GPS?

 

What do the magazine road tests say? I thought 6.9 seconds was about the norm for the non-supercharged version.

Cheers
DD

 

That sounds about right considering the crappy tires and severe traction control program on these cars. If you want good 0-60 times, get some sticky tires (drag radial, 17" rims or smaller), turn off the traction control and practice, practice, practice. Your 0-60 time will be pretty much determined in the first 60'.
Are you sure it wasn't showing the 1/8 mile time?

 

I'm not sure if it's GPS or just the car's own internal distance measuring equipment. If it's GPS then that's a pretty crappy way to measure. GPS only updates once per second so it would have to guess at the actual time.

 

I just found a website that lists self-reported 0-60 times for lots of different vehicles: Jaguar 0-60 Times & Jaguar Quarter Mile Times | Jaguar XJ, XF, XK8 0-60, XJS, XKR S and X Type and 2011 Jag 0 to 60 stats!

For the XK8's and XKR's they go from 5.1 to 6.6. I think a couple of the numbers are wishful thinking, however. Most of the XKR times are right around 5 seconds, but a couple of the XK8 times are 5.1 or 5.2 seconds. The problem with that website is that all of the times are self-reported, and most people are going to only post their best ever time, and even then they are going to give themselves the benefit of the doubt on the actual measured time. So, my 6.0 to 6.9 times seem reasonable.

 

I was thinking that SHOULD have the ability to be more accurate than using the vehicles speed sensor information, or accelerometers. However a cell phone app probably doesn't have the processing power, thus accuracy, of dedicated units. Those G-techs (accelerometer based) are notoriously innacurate unless set up exactly right, even then I have my doubts about them.

Most organizations who professionally measure a vehicles performance are using a version of the V-box these days, and it's GPS based. It can do a lot of things that have not been possible before, for example Car & Driver magazine uses the V-box for all of their testing. In their annual Lightning Lap they are able to record the actual speed of each vehicle at every point around hilly and curvey Virginia International Raceway.


VBOX USA >> VBOX III 100hz GPS Vehicle Testing, Inertial Measurement, DriftBox Drift Meter

 

The reviews that I recall looking at put the XK8 in the low to mid 6 second range in 0-60. The XKR was generally low to mid 5 seconds. You can spend an hour or two Googling and I suspect that is what most of the reviews will tell you.

 

The rags usually use the "power launch" too. Holding the brake until a predetermined rpm is reached and then releasing the brake and simultaneously floor it.

 

XK8, 6.4 XKR, 5.2 XK8 Lovers - Performance & Specs.

 

agreed with the 6.5 ish posts...sounds about right

 

At least on my car the speed value you can read with standard OBDII devices is very off, so can't be used as a base for these measurements.

 

Went out to have a few runs with Torque. My best run was 5.5s. Tried using the power launch method and with the DSC on. The DSC flashed in the message center along with the amber light and I did feel some hesitation in the beginning so I guess I was having some traction problems.

I also checked the ODB and GPS speeds and they were identical so I guess the time is more or less correct. What I'm wondering though is how much the wheel size affects the acceleration time? I've got 20" wheels... All in all I guess that's not a bad time for a ten year old car with 112k miles on the clock.

 

A couple of days ago at a rather famous hexagonal intersection in Beverly Hills where the number of turn combination possibilities approaches triple digits, I found myself waiting at the stop sign for my chance to dash across. It's a wagon wheel intersection controlled only by stop signs and the common courtesy of drivers taking their orderly turns to get from one side to the other. As I was headed south inching out from the stop sign, I saw a blacked out black late model C series Mercedes with a very loud exhaust approach from the rear and decide that he would attempt to pass on the right of me without stopping and using my car as a blocker for the rest of traffic. As he pulled up to my right, exhaust roaring, he was punching it at full tilt. I generally prefer my racing on a track, but sometimes you just need to put the whippersnappers in their place. As the Merc loudly tried to pass on the right, I punched it and left him stunned and unprotected in the middle of the intersection. No amount of coaxing his engine could even bring him close, embarrassingly defeated by an 11 year old, 123,000 mile XKR driven my me, a 60 year old "geezer." I have other quick cars, but the power delivery in this car is so linear, smooth, and perfectly predictable and available at a moment's notice with no hesitation, that I don't drive my others very often anymore. What a pleasure!

 

I'm curious to know what is 0-100 or 0-125 mph acceleration time of XKR utilizing Kenne Bell 2.6L... Did anybody make those measurments?

 

Pure performance has never been the strength of the XK8 and the numbers I read above (and everywhere on the net) seem really optimistic. Back a few months ago I digged out an old detailled review of the XK8 4.0 convertible by the german magazine Auto Motor & Sport, the 0-100km/h (0-62mph) was obtained in 7.4s and the 1000m (0.62 mile) drag race was completed in ~27.5s. That seems more realistic. My 4.0 engine is in good shape, with after market exhaust and direct air intake, but I doubt I can reach 60mph in less that 7s in normal conditions. Okay, you may do a bit better with the coupé, and by messing around with the geabox & tyres but, in normal circumstances, the XK8 performs as well as a bimo E46 328i of 193hp with a manual geabox.

Can't really comment on the XKR numbers but seems again quite optimistic to me.

 

One always wonders (well, I do, at least) just how hard the magazine road-testers are trying (or not trying) when they make their acceleration runs.

I suspect some are quite agressive, and experiment with multiple techniques in order to squeeze out the abolsute best possible results. Others, perhaps, just hit the pedal, let off when they hit 60, and leave it at that.

For example (although probably not applicable here) some of the older Jag models were a bit notorious for having automatic transmissions that upshifted well before the optimal point, even under WOT. Timed acceleration runs could vary greatly if some drivers held the lower gears manually compared to those who didn't.

I dunno. Just musing and speculating



Cheers
DD

 

I have not tried to check the time as I think to do it requires really stressing the tranny. To launch the car with an automatic, the brakes are held whille the rpms are brought up to stall speed, then quickly, the brakes are released and the throttle is opened up. The only problem is that the traction control needs to be turned off and without a limited slip diff, getting enough traction is a real problem. You are going to lose 10,000 miles off one of the tires! This car is made to be a grand tourer, not a muscle car, so it is not designed for straightline times. Its still pretty amazing for a 230 cu in engine!

 

I don't keep up with that sort of thing like I used to, but back when I did, they all did everything that they could to get the best times out of a car that they could. They'd loosen that fan belts (not feasible any longer) put a LOT of air pressure in the front tires to reduce rolling resistance, vary the air pressure in the rear tires, take out the spare tire and everything in the trunk to see if that would help, try different shift points and launching techniques, and then there are always differences between individual cars.


As I said before this website uses a broad range of such tests.

XK8 Lovers - Performance & Specs.

"The data was compiled from various magazines and web sites and should be accurate. If you notice an error, please let us know and provide us with a link so we can verify and update. This list is not complete but just a selection of representative cars; most models are US specs cars."

 

Ted--I know that intersection and dread it on the rare occasions I find myself there. You gotta wonder who the nut was that designed it.

Others--this is why I am always amazed at the frenzy for more and more horsepower. When I got my Corvette back in 1995 it had what I consider to be the ideal amount of power--300 which was high for the time but would be "lowly" by today's standards. The 300 hp was plenty to handle but the curious thing was how many times I would get whacked by some Honda sedan or similar with much less horsepower. While I generally avoided and street drags I often found myself stopped at a metered freeway on ramp which is where the Honda embarrassment would frequently happen. With all of the torque I had the real wheels would easily break loose and/or the traction control would take over (actually pushing the accelerator BACK) and I would be left in the dust while the Honda leisurely pushed onwards. Given the amount of skill it takes to properly launch 300hp and attain the 0-60 times that the magazines get, I can only wonder how one handles the 500-600hp that is becoming more common these days.


Doug