I got my "new" 2002 XKR home and brought all maintenance & repairs up to date, including new O2 sensors and fuel pump relays. I won't be driving it like a hot rod, but I did want to get a benchmark of its capabilities (and find out what the legendary thrill is like) so I tested its 0-60, quarter mile and HP.

I connected an OBD2 bluetooth and loaded the Torque app on my phone. I CANNOT be disappointed by this car, but I was a bit surprised that the recorded stats were 0-60 in 6.2 sec @ 98 mph, quarter in 14.8 sec, and max HP at 230.

Is that what I should expect at 79,000 miles using this app, or should I be concerned? The supercharger doesn't sound nearly as shrill and noticable as most of the others we drove in our quest.

Thanks for humoring a new and still-grinning owner.

 

Have you verified the throttle pedal is going to full throttle? On mine it wasn't. Do a search on "adjust throttle cable" and do that 5 minute job then report back. Was the trans switch in sport mode?

 

In addition to the throttle cable and sport mode, you should verify that the supercharger coolant pump is operating and that the secondary fuel pump is operating. A search will turn up information on both of these.

You will also see a significant increase in power in cooler weather, especially with repeated throttle application. These cars can get heat-soaked.

 

Yes, it was in Sport Mode. Here's the reading on the throttle opening (second gauge down on the left.) With the pedal to the floor and the engine off, it reads 100%, but look where it is with NO pressure on the pedal. I suppose that represents the idle setting.



How can I tell if the supercharger coolant pump is operating? Oh wait... you said a search would find the answer. I love this! It's like a treasure hunt. Thanks to both of you!

 

When verifying throttle opening, just lift the black plastic cover behind the throttle cable and have someone go to full throttle from inside the car. The D shaped pivot within the box should go fully open. If not, remove cable retainer pin and pull out hard on the cable, then re insert pin.

 

The app is wrong for a couple of reasons. A car that is 1 3/4 tonnes would need significantly more than 230 hp to do 0-60 in 6.2. A bog standard XK8 is around 6.5 seconds with 290 hp. If you want accurate statistics get it on a drag strip and a rolling road, not a phone app.

 

The "legendary thrill" was probably just that back in the day but, these days, not so much. Back in the 1990s 300HP was rarefied and 400HP was almost unheard of. Now any decent Asian family sedan gets near 300HP and are probably much lighter than our behemoths to boot.

So just enjoy riding around in the most beautiful GT cruiser ever made and let it go at that.

Doug

 

Depending on the torque, 230 RWHP could make a 3600lb car do a 6.2 sec 0-60.

Back in the bad old days our 3,400lb 5.0L mustangs were doing 5.8 sec 0-60 (14.2 in the 1/4 mile) with only 225 Flywheel HP.

The phone doesn't know what your car + driver + Fuel load weighs.

A fully loaded XKR with fuel and heavy driver could be close to 4,000lbs. Roger_B, what did you put in for weight?

If you want more HP from the app, put in more weight for the car.

 

I appreciate all the attention to my question and the excellent advice... which I am taking and learning as I follow your research cues. I did enter 4,100 lbs for the weight.

SeismicGuy, I'm certainly not planning on challenging Corvettes at stop lights; I have too much respect for this car. I just wanted to savor a moment out of time when the XKR ran with some serious company, and I wanted to see what shape this one is in.

The question that remains for me is, "If the Torque app is accurate, are those numbers an indication that there may be problems with the engine or its supercharger?" If the numbers are adequate, I'm thrilled to be driving an icon of motoring history.

 

Roger, I think an R should be faster.

Double check times with a free app like Speedview. I am not its biggest fan but it's free, GPS based (timer starts when you do, elapsed time stops when you reach 60mph or 1/4 mile as determined by GPS) and would provide a useful comparison.

I understand where you are coming from and I'd ask the same question if I was lucky enough to own an XKR and saw those times.

I hope it is a simple answer like you are going faster than the readings show.
John

 

I would double check your coolant Roger.. I just changed mine today and found the intercooler full of ketchup thickness goop which was causing my supercharger to be SUPER hot.. (blowing hot compressed air..). My coolant levels were all up but soon as I pulled that supercharger filling port I was pretty shocked.. I would think that would cause HP loss just right there.

Or maybe your step down button below the pedal isn't working or.. who knows but maybe a *more* dense day or cooler (better performance) day you'll put up better numbers

 

As hp is a function of torque, they are 2 aspects of the same thing. I think that you are talking about gearbox ratios, yes a car with a relatively low hp can be made to do eye watering 0-60 times with a moded diff and gearbox ,but they won't be able to go much faster than that. The xkr 's gearing can take it to 175 plus, with that in mind, not forgetting that its an automatic, 230hp is not sufficient to get the xkr to 60 in 6.2 seconds.

 

How brutal were you when you got that time? I don't think I would be trying to get near to the manufacturer's figures in my 15 year old XKR, because they would have been really thrashing it, without worrying about breaking anything.

BTW surely its the torque figure not the BHP that dictates 0-60 time?

 

Please keep in mind he's a 'R' version which is about 390 hp, not the standard XK which is 285.

 

This is what doesn't add up in the figures quoted.

Acceleration is a function of mass (the car) and force (torque/horsepower). ©Isaac Newton

Given two vehicles with the same mass and rolling resistance, then the one with more force being applied to it will accelerate faster.

Acceleration times:

XK8 0-60 in 6.4 seconds from 290 bhp

XKR 0-60 in 5.2 seconds from 370 bhp

Thus a 0-60 time of 6.2 seconds from 230bhp is inconsistent. Either the 0-60 time is wrong, the power figure is wrong or they both are.

QED

Hey, it's still one hell of a car...

Mike

 

I presume the "Torque" app is guesstimating wheel HP rather than engine HP, so perhaps the 230BHP is consistent with 6.2s with a 10% margin of error on both numbers.

That would imply you are getting nothing from your supercharger though.

I think a trip to a rolling road is in order.

Edit: forgot to say that for a well maintained engine you should have lost very little from the engine in the way of HP, I have no experience of super chargers though, I guess that they do have parts that will wear and eventually need replaced. Any supercharger experts here?

 

I see a number of peoiple using the term "rolling road." Does that refer to to anything special... a product or a technique?

 

It's a dyno.

 

Good point RD. On reflection, it's the only calculation that doesn't require an estimation of powertrain losses, and it's the figure that matters anyway.
Thanks.

Mike

 

These are the parameters Torque recommends when testing.

Horsepower
Horsepower and Torque can be measured quite accurately though the app "Torque" - measurements taken are 'at the wheels', not at the flywheel

Setting up
It is quite important to fill out the vehicle profile for this with the correct weight of the vehicle - using the manufacturers advertised weight unfortunately won't be close to your real weight as it often does not include differing specifications of the same vehicle (alloy wheels vs steel wheel weights for example). The most accurate way to weigh your vehicle is on a weighbridge.
Alternatively, you can approximate from the manufacturers specification, plus your weight, plus the weight of the fuel, plus the weight of any extra equipment in the vehicle.
How to do the test
Firstly, make sure you abide by all local laws and make sure that you are safe at all times!
The test should be performed on a flat track. Going up or down a hill/slope will lead to inaccurate readings.
Start from a slow rolling start (about 5 to 10mph) and accelerate until about 55mph. This will give you the most accurate peak value for your vehicle.
Note: If you spin the vehicle wheels then this will cause the figures to over-read

For best results on older vehicles (or vehicles with a slow sensor refresh) make sure that:
Faster Communication is enabled in the app settings
Only have the displays you are interested on the screen - the more displays you have visible, the slower the sensor update and this can degrade the accuracy of the HP/Torque readings on slower ECUs