I finally got to try my 2010 Jaguar XFR at the Drag strip yesterday. The car ran a great ET 12.55 with a 1.83 60ft, which was great. But I was really disappointed with the mph, 111.44 on that run and a 111mph on every run with a best of a 111.93. I really thought the car would have more mph than that. With all the articles that I've read in magazines ranging from 12.9@112 to a best of 12.60@116 , I was really off in mph. The air was cool 16 degrees Celsius , not warm enough to lose HP. The car is stock with 2 K/N air filters and a Mina axle back exhaust. Sometimes I begin to wonder if the car would have ran better with the stock mufflers. My 2004 Jaguar S-Type R ran a best of 13.27@105mph bone stock, and when I put the Mina cold air, Mina pulley (1.5lbs of boost more), Mina axle back, I was never able to beat the time of the car bone stock. Do you guys let the tranny shift on its own or do you shift it yourself? I was letting it shift on its own on sport mode. I would like to have your opions on this and what you guys think.
Thanks, ahead of time.
Marco
Here are some pictures of my car:

 

Nice, but I find it very interesting. Your XF is a 4.2L car right? That means it should be pretty similar to your STR. The two cars should weigh about the same so your lowered ET was surprising.
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Understeer is when you hit the wall with the front of the car
Oversteer is when you hit the wall with the rear of the car
Horsepower is how fast you hit the wall, and
Torque is how far you take the wall with you

 

That is curious, especially with the pulley. Not sure if there is a weight difference between the models, as I don't know anything about the S-Type. Nice 60ft. time though. Hoping to get there when I go next time now that I have better rubber.

And PAB, the 2010 XFR is a 5.0, not the 4.2.

 

No, he has a XFR = 5L Supercharged motor with 120hp more than the S-type R.

 

>he has a XFR = 5L Supercharged motor with 120hp more than the S-type R.

Well that would make a difference!
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Jaguar - it's not an automobile, it's a Motorcar
Current: '08 S-Type 4.2 "Satin Edition" (250.06 hp / 259.67 torque)
Past: '05 X-Type 3.0/auto Jaguar Racing Green

 

[QUOTE=pab;1322539]Nice, but I find it very interesting. Your XF is a 4.2L car right? That means it should be pretty similar to your STR. The two cars should weigh about the same so your lowered ET was surprising.
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It is a 5.0 with 510HP

 

My XFR has no pulley, bone stock with mina axle back exhaust. My S-Type R had a pulley, but ran its best time bone stock. The weight difference between the 2 is about 350 to 400lbs.

 

Sorry about the confusion on the pulley. That sounds more in line then, especially with the weight difference.

I was able to get to 117.04 by playing with different launch scenarios, but my quickest time was at 116.79.

We're you getting wheelspin or was DSC taking power?

 

The DSC was completely off, no wheel spin, great traction. God, I wish I had your mph. Was your car bone stock when you ran those mph? What does your car run on the strip? Tell me if your times are with mods or no mods.
Thanks,
Marco

 

Those times and mph are with a tune, pulley and exhaust mods. But my tires sucked at the time (BTW Hankooks are good for normal driving but suck for corners or traction) and I spent the whole day fighting wheelspin and never could break 2.0 60 ft. times. I got my best trap speed leaving in second and power braking up to about 1800 rpm. But I have a lot more hp and torque than stock so it's more of an issue now.

I have new Bridgestone S-04's and traction from a stop is noticeably better. If I left hard TC would ALWAYS cut in hard. Now, even if it slips a bit it doesn't fall flat on its face like before. I can't wait to go to Famoso on Halloween. Was supposed to go recently but it was 97 degrees there and no good times would have been achievable in that kind of heat anyway, so I postponed.

 

My best time was 12.434 at 116.79. My 60' was 2.05 and my 1/8 was 8.206. It's a notoriously slow track (by .2 to .3 as it has a slight elevation change) and not sure how mph will vary at another, better prepared track. Still have a lot of work to do with my technique. First time ever with a tree. Done some racing with friends but nothing at the strip until then.

 

Great 60' times... Not sure why the MPH is down so low. I would have expected more as well. I wonder if tweaking the Jag is throwing off the ECU? There are so many more inconsistent results after tweaking posted on this forum than without.
So for the meanwhile I plan to stay stock...

Out of curiosity -- where is the track in relation to Montreal?

 

The car isn't tweaked, its bone stock, except for the Mina axle back exhaust. I am not sure, but I might have found why my car was off on mph. I've been driving my car on 94 octane fuel which contains 10% ethanol. I think this fuel isn't good for my car and might be slowing it down. When I get a chance I will try to go back with the recommended 91 octane fuel and see what happens.
To the guys that race these cars what fuel octane are you guys running?
I live in Montreal, and the track is about 35 to 40 minutes away.

 

94 octane should be good for the car not bad. It will allow the car to advance the ignition as far as it can to give you the most power. The 10% ethanol is something that if you can, you should take out of the equation. I've heard back east you can still find stations the sell "pure gasoline"

I'm in California and I get the worst gas ever. So I'm very happy I can put up even decent numbers with the fuel I have access to. I'm going to do pump gas this next trip to the strip with some octane boost added, but next time I'm seriously considering getting a 5 gal. can of 100 octane unleaded to see what it does.

 

Maybe in your case it might help since you run extra boost and a tune. But I think the extra octane on a stock car is not going to do anything at all , and what I am thinking is that it could actually maybe even hurt the performance if the extra octane is not needed. The manufacture programmed the ecu to run on 91 octane fuel, that might be what the car needs to run its best. In magazines like car and driver or motor trend, the fuel used was 91 octane and the cars ran between 112 to 116 mph bone stock. The next time I go I will try the 91 octane without the 10% ethanol.

 

Getting rid of the ethanol will be the biggest benefit for sure.

 

Keep in mind that elevation as well as dew point all impact hp and average hp is what is gets you mph. The ethenol can be a factor as well as octane is an raises the flash point of the fuel. Great for lots of compression or boost as it guards against preignition but if you dont need it it adds to a decrease in power. Your performance is not far off the magazines so all of the issue can be combining to cause your result. 116 is mot setting the world on fire but the faster you go the harder it is to go faster and the more these "little" things matter. For a big heavy car i think you are doing really well!

 

Here it's 93 with 10% Ethanol. Would love to try some of the 100 oct unleaded available from the racers to see if it increases power but it's a little too expensive

 

Do an Internet search for ethanal free gas stations in your sate or providence. I found a list for New York State.

 

Going back to the track this Sunday with Shell 91 octane fuel with no ethanol, and I put back the stock oem axle back exhaust. I am curious on how the car is going to run. I will keep you guys posted.