I was very curious the xk 5.0 non-supercharge
1/ how fast and how many hp?
2/ what mods done to achieve that
3/ any special advise or pointers in regards to the mods

i know most of the people in the form saids the same thing " dont waste time and get an xkr" but i am sure there are a fair number of us that would be curious what the limit is with the xk.
Thanks

 

Only thing I've ever seen is xf 5.0 on YouTube running 13.9/14

I've got the 4.2 the quickest time iv posted is 13.72 (cats, tune, x-pipe)

Haven't had a proper chance to go back down after the diff ratio change and enlarged throttle . Thinking the best would be a 13.5

Surely with similar mods excluding the diff ratio swap the 5.0 would have to be in the low 13s

 

Thanks for the info.. Yet I cant believe no one on this forum has ever curiouse or had post any information - data in regards to the fastest mod with an XK 5.0 non surperchange.

 

Dennis, I think that most don't buy a standard XK for the outright performance, it is just a well balanced and powerful GT cruiser.

Those interested in outright performance, and the ensuing figures will be steered toward the XKR.

By way of example I had a 4l X100 and only twice (in 14yrs) had it dyno'd before/after some performance mods, I was more concerned about economy (?) which I got up to 60mpg in ££ monetary terms (50mpg in $$'s)

I've had my XKR dyno'd 3 times in less than 3 months and couldn't care less about economy (thankfully)!

 

I do understand and agree with your logic. Yet I was again just curious thinking there must be somebody out there that would mod an XK to its capacity and I was wondering what that would be in addition to the way they accomplished it. I think that would be a fair enough question to ask even knowing that those that probably into higher performance would likely get into an Xkr.

 

I don't think we have ever had anyone with a 5.0L XK on this form do a tune or any other performance mods. You might want to check the XF guys as they may have done something other wise if anyone here has they most likely would have joined in the conversation.

 

You're going to have the same problem with a 5.0L XK as everyone else had with the 5.0L XKR, until recently nobody was really able to tune them properly.

Plenty of examples here on the forum of people who through lots of dollars at tuning companies and got no real results (i'm talking about the X150 with Denso ECU, it's a different story with the newer models that run Bosch). But there are a few Denso cars putting down good numbers at the track, where it counts. They all have one thing in common...

In any case, to get the most out of a naturally aspirated motor, you need to make it breath better, that means a highly efficient exhaust, and efficient intake.

The N/A motor already has a similar dual-intake as the S/C, so I wouldn't be too worried about it being restrictive. You might want to look at a custom intake to get rid of all the resonators and what-not, but to be honest I don't think there's too much to be had there.

On the exhaust side, and XKR-S style centre section with x-pipe, and some high-flow cats, will be a must.

Nobody is making headers for these cars/motors, and even if they did they would probably make them wrong anyhow.

Exhaust, cats, and a proper tune, you will get more grunt out of the 5.0L XK, but anyone who promises you big numbers is going to be full of it... I really don't know how much power JLR left on the table with the naturally aspirated 5.0L, there will be some, but don't have your expectations set too high...

 

When I owned my 2012 XK 5L NA I had a Mina Exhaust and and ETG tune done to the car. Following those two mods it dynoed at 440HP as compared to 385 when delivered. Unfortunately I did not run a dyno on it before the mods.

 

Find it strange in the respect of people buy certain performance vehicles like wrx, s5, V8 vantage, S3 knowing all to well there is a higher performance model in that brand ..this doesn't seem to be the case with the xk for those who want performance they go straight to the xkr.

 

Steve, not strictly true, in 2004 I bought one of the first production XK8's in launch Antigua Blue for £14k gbp, happily married at the time, the only mod I did was to have it LPG converted as (at that time) LPG was a third the price of unleaded in the UK.

In 2010 when I'd ditched SWMBO I set about with performance mods

So then set about:

Performance straight through zausts
Cat bypasses
Carbon dynamics air intake
Terraclean
Royal purple fully synth
larger cleaned and calibrated injectors
Reprofiled cam's
Performance manifolds made by hayward and scott

Took a humble 290 bhp up to 340 (Dyno'd at Noble's in Leics) as was led to believe that the tranny wouldn't take much more

Standard tune, and YES the 15% hike in power could have been gotten much cheaper by buying an XKR to start....it was just the joy of modding and loving the car you own

Hope this clarifies things?

 

Well, yeah, but then you're just modding TO mod.
i.e.:
I bought a Mustang with 88 horsepower.
It now has well over 1,000 horsepower.
Not a whole lot of the original car is left there.

 

Perhaps you could share what you're attempting to accomplish. Many times over the years when I was a member of a racing team, the 'fastest' car wasn't necessarily the one with the most horsepower.

If you're wanting to improve the performance of the vehicle through corners, suspension and tyre changes are the first step before touching the engine.

If you plan on operating the vehicle on public roads in California, any engine modifications that aren't CARB certified will cause the vehicle to fail a smog test.

 

I have to give the original poster some originality points.

The idea of tuning a 5.0L XK had never even occurred to me.

Perhaps the first thing I would want if doing so would be a LSD

But then, the price between a 5.0L XK, and the cost of upgrading a 5.0L XK added together surely must be more than beginning with a stock 5.0L XKR that already has an electronic diff.

 

Sorry but it doesn't sound very plausable for a NA 5.0 engine to gain that much. Do you have your Dyno charts ? Track times?

 

Sorry I hadn't responded to my original post questions till now because of the holiday seasons. I want to firstly thanks to all the valuable comments and advice to my curiosity. To answer what some of the questions on the post, I feel that even without the SC like the XKR, the XK is by no means a low-performance car with 385 hp. Therefore I feel that If the hp can somehow bump up to anyway around 450 plus, its performance potential wouldn't be so far compared with a stock xkr per say. I think that from this thread; we can already see that with a few simple reasonable mod that we can well achieve this goal.
I.E.
- Better air Filter ( About 2 to 3 hp gain)
- Ecu Tune ( about 30hp gain)
- Exhaust mod with xpipe and resonator, muffler and possibly cat delete/ 200 cell cats installed ( about 20 HP gain or more )
We are already at about 51 to 54 hp gain without even touching intakes or ,,,,,,,, That put us to around 440, not including the subtracting the weight off the car in the removal of the muffler which must be at least weights 50 to 60 pounds which can only be a gain to the acceleration and even overall speed band on the performance. The last thing is that after talking to Paramount, they told me that they have a water methanol injection kit for the XK that can increase about 30hp For around $500us.If that is the case then we are looking at another 30hp gain which will total the hp gain to around 80 to 85 and now we looking at the hp gain close to 470 which is closing in on the gap between a stock xkr with not a huge amount of money spent.
Please let me know the above speculation are realistic and my speculations have any merits.
Cheers.

 

Never heard of methanol injection on a n/a vehicle also forget about dropping 60-80lbs with the muffler delete realistically stick to ecu, X pipe and 100/200 cell cats .

LSD would also be handy at putting the power down I'm still thinking a very low 13 would be on the cards with 50-60hp possibly gained.

 

I have had extensive discussions with the R&D department manager over at Paramount who specializes with jaguar modifications. He has informed me that they had come up with a water methanol injection kit for the F-type yet also fits the XK (XK 150). It runs about US $500.00 and an hp gain of around 30.
I also have a question in regards to the exhaust. Currently, I have an Xpipe muffler in the middle section of the car with muffler and resonator deleted. I am very happy of the way it sounds and the levels are perfect.
My Question is How much difference in power gain and noise factor does switching to a 200 cell cat
How much difference if I do a cat delete again in regards to hp gain and noise level factor

Thanks, again with all your advise and valuable;e info.

 

I remember seeing a test on a 4.3 Aston Martin and it gained 8whp with it decatted

Forget the 200cells go 100s if trying to gain all the power possible

 

But how about the sound level on both 100 cell and decat. Would it be significantly lounder.

 

I've got the 100 cells and it's loud hence why I'm only run 2 out of the 4 tail pipes I would hate to think how loud it would be decatted then