I now own an 04 XJR and love it! Sadly there are few options for performance upgrades...I have been waiting for the 2010 and up 5.0 XK or XKR get into my price range. They now are there! I know the XKR is a beast already, but what does it take to get more out of it without breaking the bank? Same goes for the XK...I want an "R" but I will be stretching some $$$ wise...Can a XK reach 450 BHP with basic add ons? Thanks

 

Pretty much ZERO bolt-ons for these cars.
You can get the pulleys changed on the supercharger, but of course you'd need to start with the -R variant, and you'd already have over 500 hp anyway.

Tunes are hit-and-miss, depending on who you talk to, and not many places even do them. Doing drastic mods to the exhaust sometimes causes more problems than any benefit you may get.

There are involved kits to get more power, but the total cost involved is around $4 grand, and they are a good amount of work. Of course, those are ALSO only for the already supercharged -Rs.

To get the BEST power from a non-supercharged XK is to put all your "upgrade" money you would spend into buying an XKR. Seriously.

 

If you want fast, the XK will suffice, but you'll keep asking yourself "why didn't I get the XKR?"

Just do it. You won't regret it.

 

Agree. If you are trying to squeeze 70-80 more HP out of the N/A 5.0, I think you are in for a huge amount of work, money and ultimate frustration. An easier, cheaper and instantly gratifying way to get another 115 HP is to get the XKR.

 

how about a 09 xkr 4.2 ?
with the correct mods your up at the 500hp mark

 

I agree with Steve. The 4.2 SC sounds much better and is more receptive to cheap modding than a NA 5.0. If noise is your thing, go 4.2 for sure. Drive a 4.2 (NA or SC) and wind it up then drive a 5.0 NA and wind it up and you will see what I mean, though the 5.0NA is a lot quicker than the 4.2NA.

 

I had an ETG tune and a Mina Gallery exhaust on my 12 vert. It dynod at around 435 hp up from 385. total cost was about $2500.

 

Very interested to see if anyone has actually taken their n/a 5.0 to the drag strip and how it performed

 

It is interesting that with all these discussions about tuning through ECU, supercharger pulley, intercooler upgrade, headers, 200 cell cats and exhaust systems, there has been little discussion of experiences with nitrous. Seems to me that nitrous might be an easy 75-100 hp gain on an XK at a reasonable cost.

 

I didnt with my XF but obviously I did give it the hammer from time to time. It was a lot quicker than a NA 4.2 (but not amazingly so) but heaps slower than a SC 5.0 (as in another league), and it lost its pep around the time that the 5.0 SC is really coming on around 100kph. Factory spec is about 5.5 seconds 0 - 100 and that is probably right, it didnt feel any faster though "feel" is a very unreliable measure. Ultimately the difference in feel in a car from 6.5 to 5.5 seconds is nowhere near the difference in feel between 5.5 and 4.5 seconds, I found the 5.0 to be solid rather than lively and certainly not frisky.

 

Agreed. Fancy exhaust is nice mod, but I don't think it'll actually improve performance by much. Will feel more visceral which makes it feel faster. The good exhausts aren't cheap. I would just go for an XKR and leave it as is. BMC air filters are long hanging fruit, but I don't think it's worth swapping out OEM for them unless the air filter needs to be replaced.

Sounds like the XKR may already be a stretch, so I would advice to keep any extra money towards keeping it in top shape vs. spending it on mods.

 

Wise words, especially that last part. You gotta ask yourself, how many 510hp "SuperCars" have you owned? These things are obviously finicky as it is , why start modding and reducing the reliability even more, when the truth of it all is there are few, very few, that can truly handle all the power and performance they have stock.

Happy Friday,

Dave

 

Great advice! It sounds like the "R" is the way to go! My XJR has around 410 BHP with the few mods it has. I had a XJ before it with 300 BHP and sold it quite quickly when the "R" went into my price range...Don't want to make the same mistake twice...At 510 BHP I am sure the XKR is quite a little rocket ship! Has anyone here had there XKR weighed on a CATS scale?

 

After reading multiple threads, I think the general consensus is that the water pump will fall out right after the battery dies.

 

Dont overlook an essential mod that pays dividend.
I dont care for power, my 520hp would mean nothing to me if it wanst instantaneous.
Cleaning and restoring an intake or even polishing, can give you the power it once had and more importantly the quicker reaction times.

Towards that end a 4.2 is easier to get to factory specs and beyond.

 

I look at these discussions as 2 different issues. One being HP and the other 1/4 mile performance both in time and mph. As for the HP discussion I don't consider seat of the pants as a quantification of HP. Put the car on a dyno before and after and take the readings. The results in HP and Torque are on the readout. As for 1/4 mile times and speeds there are numerous conditions that cause this to be varied. But if you use the same strip with the same weather conditions and the same tire types then you should be able to optimize your runs. Once again show me the tapes and I'll believe the results. Just my 2 cents.

 

Or if you really want to be a happy camper....



....



...just buy one of these...

 

...or wait a year or so and buy one of these, the new VW All Electric Bus is coming back, including the Camper version.


Cheers,

Dave

 

Well I got an 8K loan approved...That and selling my Mercedes will yield me enough to buy a 2010 or 2011 XKR! I don't have any debt other than my pretty low mortgage, but its just the thought of paying a loan makes me cringe...

 

It may vary from person to person, but I know that I would not enjoy a car I had a loan on.

From a performance standpoint, unless a particular car has your heart, the easiest way to mod an XK is to get an XKR.